Science topics: Chemistry
Science topic

Chemistry - Science topic

Chemistry is the science of matter, especially its chemical reactions, but also its composition, structure and properties. Chemistry is concerned with atoms and their interactions with other atoms, and particularly with the properties of chemical bonds.
Questions related to Chemistry
  • asked a question related to Chemistry
Question
6 answers
I have a 200 mg/ml ampiciline solution, how much should i add to 300 ml of LB medium to get the final concentration of 40 ug/ml?? How much bacteria (in ml) should i add to 75 ml of medium to dilute the culture 50 times??
Relevant answer
Answer
1. C1*V1 = C2*V2
200 mg/ml * V1 = 40 ug/ml * 300 ml, or V1 = 0.06 ml (of ampiciline)
2. If you mean 75 ml is the total volume of final medium, then:
C1 * V1 = 75 ml * C1/50
V1 = 75/50 = 1.5 ml (of bacteria)
  • asked a question related to Chemistry
Question
5 answers
Hello everyone,
I have 5 Samsung 21700 - 50 E (NCM chemistry) cells. I want to do basic charge and discharge by connecting it in series. Does anyone know if there is a cell holder available online for single cells? Or how to connect these cells and make contact?
Thanks in advance
Relevant answer
Answer
I totally agree with you
  • asked a question related to Chemistry
Question
3 answers
I need to get BrHPP for expanding Tgd cells, so if anyone knows about a biotec/chemistry company that has it commercially available I would appreciate the information.
Thanks!
Relevant answer
Answer
INNATE Pharma (Marseille, France)
  • asked a question related to Chemistry
Question
4 answers
Study of different types of high school chemistry teaching methods in California
Or Texas or other states
Relevant answer
Answer
It varies from school district to school district but typically qualified Chemistry, Physics and other sciece teachers are hard to find. When they get somebody they try to keep him/her and if they can't find anyone the teacher and students learn the subject together.
  • asked a question related to Chemistry
Question
19 answers
Hi every body,
I have tried to synthesis aliphatic isocyanates from their acylazide compounds based on Curtius rearrangement. Based on articles, the converting of acylazide to isocyanate must be done through a simple thermal treatment in toluene or benzene at 1-2 hours and via the evolution of nitrogen gas during reaction. However, I have repeated it many times and no isocyanate is formed after reaction. Could you please share your experience with me?
Unfortunately, I found no repeatible results from articles.
Thanks in advances
Relevant answer
Answer
Dear, did you characterized the product? This reaction requires a rigourous anhydrous conditions. May be the solvent is not dry enough. If this is the case, the NCO formed will immediately converts to an amine. My Regards
  • asked a question related to Chemistry
Question
8 answers
Good evening,
I am looking for methods according following topic:
Vegetable oil (raps) contaminated with hydrocarbons (e.g. motor oil) shall be purified and separated from hydrocarbons. (Usage for in-situ soil remediation)
Thank you all in advance, I am looking forward to your ideas and suggestions.
BR Paul
Relevant answer
Answer
You can use Soxhlet or Soxtherm to separate oil by solvent extraction process and Hexane/ Methanol/ Acetone as a solvent.
  • asked a question related to Chemistry
Question
3 answers
How is chemistry taught in schools in the United States?
A comparative study of high school chemistry education
Relevant answer
Answer
Hello,
Teaching of chemistry in Argentina is almost similar to other part of the world.
Thank you
  • asked a question related to Chemistry
Question
32 answers
Chemistry is frequently termed the "central science". It underlies the foundation of modern civilization (drugs, plastics, textiles, dyes, fertilizers etc.), but the public perception of chemistry and chemicals is often negative. What can we do to overcome public misunderstandings of chemistry?
Relevant answer
Answer
I think the public perception about chemistry and chemicals is negative due to environmental education. Nevertheless, drugs, plastics, textiles, dyes, fertilizers, pesticides etc. are still purchased and used on large scale.
  • asked a question related to Chemistry
Question
3 answers
Hello,
I would like to calculate the monomer molecular weight of cellulose acetate butyrate (cf. attached figure). The average molecular weight of the polymer is 30000 g/mol. However, the polymer bears different residues (Acetyl, Butyryl , and Hydroxyl groups) and the extent of labelling is given as mass fraction in the datasheet as:
12-15 wt. % Acetyl
36-40 wt. % Butyryl
I assume the (average) remaing 43.5 wt. % are hydroxyl groups? There is no more info on that.
How can I calculate the average molecular weight of one monomer?
Relevant answer
Answer
Dear Philipp Selenschik, the best way is to get experimentaly the average MW via viscometry, GPC, or any other available technique at your place. My Regards
  • asked a question related to Chemistry
Question
7 answers
My team and I are curently working on a project is focused on preventing microplastics and collecting plastic particles up to 2 * 2mm. Our biggest concern is harming sea life and destroying plankton. I hope if you could advise us in which direction to go in our research. Is there a possibility that the filter / mesh and microplastic can be transformed by a biochemical process into something that would not harm sealife?
Relevant answer
Answer
Yunus Shukor thank you very much for your help! We will try to find some mechanism to separate plastic from sea life :)
  • asked a question related to Chemistry
Question
4 answers
My team and I are curently working on a project is focused on preventing microplastics and collecting plastic particles up to 2 * 2mm. Our biggest concern is harming sea life and destroying plankton. I hope if you could advise us in which direction to go in our research. Is there a possibility that the filter / mesh and microplastic can be transformed by a biochemical process into something that would not harm sealife?
  • asked a question related to Chemistry
Question
37 answers
I am not sure if any one study on this topic. It has been observed in certain cases that success-full researchers have poor academic record. These are exceptions, I am interested to know any study on this topic. Please also cite examples that shows negative or positive examples. Ideally there should be high positive correlation, if it is not than why?
I mean if person got good grade/marks or rank at school/university level will be a grate scientist. For example if topper of JEE (top exam in India for getting admission in engineering college) join research, he/she will be best scientist in the world.
Relevant answer
Answer
From my long experience of teaching, the researchers who have rich researching CV usually have poor teaching records and vice versa. That is especially true for the universities that haven't a sufficient researching budget. The reason behind that is that researching needs more time at the expense of teaching.
  • asked a question related to Chemistry
Question
4 answers
Hello,
I did a oxygen plasma surface treatment of a polydimethysiloxan surface. i coated it with two different materials and the bonding improved significantly with one of the materials.
the other material wasnt affected at all by the plasma treatment.
Now i want to draw conclussion about the polymer that are used in this materials. Which kind of polymer bond with a oxygen plasma treated pdms surface?
I think the material with the improved bonding is a silane-terminated polymer, but i am not sure about it.
Please let me know if you got some knowledge about this topic or any hints for me
Thank you
Relevant answer
Answer
I guess that the hydroxyl-terminated polymer will have a strong bond with the plasma treated PDMS. Because after the treament with oxygen plasma, PDMS surface will be covered by a lot of hydroxyl group.
  • asked a question related to Chemistry
Question
4 answers
If I dissolve 35 g of NaCl in 100 ml, what will be the approximate specific gravity?.
Is it 1.35? or is there some trick?
I read that saturated NaCl soltion has specific gravity of 1.2.
Also I read 35.9 g of NaCl can dissolve in 100 ml of water (which will approximately give 135.9 g/100 ml solution.
it means 1359 g/L, which means 1.359 specific gravity.
I am bit confused. (did I do a mistake?).
please help me.
Relevant answer
Answer
Specific Gravity is calculated based on the weight of a substance dissolved in particular volume divided by weight of an equal volume of water. You can try this method to calculate the specific gravity of a substance.
  • asked a question related to Chemistry
Question
2 answers
Hello all
Thanks for answering my previous questions. I am making perovskite LED and intend to use PEIE on zinc oxide layer as ETL. But I am not sure what version of PEIE to us. There is the one with Mw 70000 g/mol which is not available , but the one with Mw = 110000 is available. But I am reluctant as I do not what effect high molecular weight will have on the performance of LED. I anyone could guide me with this it would be helpful.
Thanks
Jitesh
Relevant answer
Answer
The ETL must satisfy specific requirement to function properly:
- The electron concentration must be as high as possible.
- The mobility of electrons must be also as high as possible.
- The energy levels must must match those of perovskite.
The lumolevel of the ETL must be lower than the conduction band of the active layer.
What is the effect of the molecular weight on these parameters must be known to judge which material alternative will be more suitable.
I would propose that you pragmatic on the issue and make planned experiments with the materials to evaluate it. Or you can measure the electronic properties of the material to assess its properness.
Best wishes
  • asked a question related to Chemistry
Question
3 answers
Chemical engineers translate processes developed in the lab into practical applications for the commercial production of products and then work to maintain and improve those processes. They rely on the main foundations of engineering: math, physics, and chemistry (though biology is playing an increasing role). The main role of chemical engineers is to design and troubleshoot processes for the production of chemicals, fuels, foods, pharmaceuticals, and biologicals, just to name a few. Chemical engineers work in almost every industry and affect the production of almost every article manufactured on an industrial scale. They are most often employed by large-scale manufacturing plants to maximize productivity and product quality while minimizing costs.
Students (max of 5 student per group) are asked to write a 10-15 page essay (inclusive picture)
emphasizing the the critical contribution of chemical engineering to a pathway to sustainability
Submit your article to the google classroom in pdf format
Relevant answer
Answer
Nor Maisurah so what is your question?
regards,
GB
  • asked a question related to Chemistry
Question
3 answers
If I have a solution that has an unknown amount of NaOh and NaCl, could I determine both concentrations using an electrical conductivity probe and a pH probe together? Is this possible? I can't figure out how to separate the NaOh and NaCl out during the concentration calculations from conductivity.
  • asked a question related to Chemistry
Question
9 answers
I am doing my thesis and would like to extract triglycerides from Olives or Olive Oil. I will be analysing the amount of triglycerides that are present in the olives or Olive Oil I will be testing. I would also like to extract them so that I may convert them to Fatty Acid Methyl Esters for biofuel. Does anyone know and/or have any papers that I may use? Thank you.
Relevant answer
Answer
Hi;
I worked on Nigella sativa oil, and I isolated the neutral lipids by soxhlet and then by chromatography on silica column. In the most nonpolar fractions, I determined the triglycerides using HPLC-ELSD detector. I haven't published this last part yet. for the extraction steps, please read these articles. I will be at your disposal if you have any questions.
Widad Sobhi
1- Sobhi et al., 2016. PEffect of lipid extracts of Nigella sativa L. seeds on the liver ATP reduction and alpha-glucosidase inhibition.
2. Sobhi et al., 2011. Hepatotoxicity and Langerhans Islets Regenerative Effects of Polar and Neutral Lipids of Nigella sativa L. in Nicotinamide/streptozotocin-Induced Diabetic Rats
  • asked a question related to Chemistry
Question
3 answers
If you were/are researching in field of transport in porous media, Let's share some information about current researches in field of "Transport in Porous Media" and its applications such as CO2 storage or in chemistry engineering.
What has been/did you investigated?
What is going on right now?
And which areas in this field has remained untouched yet?
looking forward to receiving your comments.
Relevant answer
Answer
Hello, thank you for proposing this question.
I have been working on estimating gas permeation in 'gas diffusion layers' (GDLs) used in PEM fuel cells for power generation. During my course of research I could essentially utilize fundamentals models into working experiments and secure results. However, I would rather specify the challanges here, and would expect the community to help me with some leads.
1. Transport of gas in porous media, can be affected in more than one way, however the concept of Knudsen diffusion (in relation to the nature of gas) needs a far more rigorous interpretation.
2. The influence of relative humidity (Dry gas+vapour) flow in the porous media also needs a strong understanding.
Thanks and regards
  • asked a question related to Chemistry
Question
9 answers
In our research in scientific papers and handbooks, we probably face two different scientific chemistry terms, which apparently are the same, however they are totally different.
These two chemical terms are "Absorption" and "Adsorption". What do you think ? Are they the same? If your response is negative, so what are the differences between these two chemistry terms ?
Relevant answer
Answer
The term adsorption is used when something is soak (поглащается) by a surface. Surfactant adsorption by activated carbon. If something is soak (поглoщается) by volume, then the term absorption is used. Sound absorption by liquid, gas absorption by liquid.
  • asked a question related to Chemistry
Question
8 answers
Thanks a lot for your answers.
I have one more question: after synthesizing ZnO nanoparticles , I am not able to separate from the original solution (dispersion actually). The recipe is as follows:
1.5 mmol Zinc acetate dihydrate in 15 ml DMSO stirred at 30 degree celsius. then 2.8 mmol tetraethylammonium hydroxide pentahydrate (TMAH.5H20) in 5 ml ethanol is dropped in the solution. The solution is kept stirring 24h prior to the precipitation process. The ZnO nanoparticles were precipitated by ethyl acetate, and washed with ethyl acetate and ethanol for one more time. Finally, the obtained ZnO nanoparticles were dispersed in 8mL ethanol and filtered with 0.45 micron filter before use.
I have some major questions in this process:
1. How can I separate the ZnO NPs for washing? I tried centrifugation at 6000 rpm but i could not get rid of the solvents (DMSO and ethanol).
2. What is the volume of ethyl acetate to be dropped for the precipitates?
Please it would be great if anyone could help me resolve this issue.
  • asked a question related to Chemistry
Question
4 answers
Kindly suggest me some good papers regarding a comparative study on various organic solvents used as dispersion medium for graphite powder. The application is to make a graphite paste and used the slurry for coating on TCO using doctor blading deposition technique.
Relevant answer
Answer
Dear all, if you want to get a complete vision on the most important solvents search for 'exfoliation of graphite to produced graphene', a wide possibilities of dispersing solvents are available. Meanwhile, please check the following RG thread. My Regards
  • asked a question related to Chemistry
Question
4 answers
I am a young researcher studying the depolymerization of plastics. I still do not have great insights about how to identify great research.
I often read highly cited research in elite journals such as Nature or Science. There, I see that many chemical reactions are also reported with very few number of replications (a lot of times, just one!). How is it that this research becomes high impact of it is not sufficiently reproduced for a large number of samples?
Relevant answer
Answer
Because in chemistry research we dceal with facf and not behavoiu. r s
  • asked a question related to Chemistry
Question
5 answers
Hello,
I have the feeling that everything in chemistry related to information and data in particular is very sharded and obscured. Are there any projects ensuring more transparency and openess of the data? I am getting quite lost to be honest and would wish for more standards and unity in the field.
Thanks,
Julian
Relevant answer
Answer
Look at Crystallography Open Database (COD). It's a free database for crystal structure. You can download the cif files to perform analysis and Rietveld refinement.
  • asked a question related to Chemistry
Question
4 answers
Greetings.
During experiments and reading about MOFs, I found something that is strange to me.
For instance, in MIL-100/101, the secondary building units (SBUs) are [M33-O)(O2CR)6L3]n+/m−, while some reports claim that their as-synthesized MOFs are constructed by [M33-OH)(O2CR)6L3]n+/m−.
Both of these SBUs are 6-connected, topologically they are the same. But from the aspect of chemistry, O-center or OH-center makes a lot differences especially in the valances of related metal ions (for instance, Co2+ or Co3+, Fe2+ or Fe3+, etc.) and in the counter ions in pores/L sites (like dimethylammonium ions, coordinated fluoride ions).
I am wondering, is there any way that we could determine the actual form of this 'center' ?
Relevant answer
Answer
Locating a single proton from e density difference maps would be tricky to say the least. Structurally, μ3-O2- will be planar, whereas μ3-OH- will be pyramidal.
There are physical techniques like magnetometry and EPR that may help you assess the spin of the metal ions if they are magnetic.
  • asked a question related to Chemistry
Question
4 answers
Hello fellow chromatography experts. This is a subject for a fruitful discussion that everyone can benefit from. To make it helpful, I appreciate that you provide a reference to support your preference.
The topic is: When to use Linear fit for the calibration curve, and when to use a Quadratic fit? Is it analyte-dependable, which means the quadratic fit is reserved for a group of analytes sharing a specific chemistry for instance? Or is it a technique-dependable, which means if the technique is Gas Chromatography then a linear fit should be used, and so on? Or is it a column-dependable, you know the drill!
The second part of this discussion should be about the proper weighing power when making the fit. Again, is the weighing power is dependable on any factor I mentioned earlier or did not mention at all, or is it just a user preference?
Let me add to these two topics another one. If you calibrate your instrument with a five-point calibration curve, and after a number of injections you decide to inject a control sample to check your instrument's response. What percent deviation from the initial calibration you would accept before recalibrating?
Let's discuss these topics and make our discussion a good reference for beginners in the chromatography field.
Relevant answer
Answer
Please read my responses again. No opinion(s) are given except that your question does not address the features available in most research grade chromatography software. Curve fits can not be categorized into just two types, linear and quadratic. You make it sound like we must choose only between these two choices. Are you using a software package that limits you to only 2 types of curve fits? If so, that may pose a problem for some sample types. Why do you limit this to just two curve fit types when in fact, several types may be needed for some sample types (e.g. the n-polynomial fits are useful too)? Some real world samples require far more than 2 (proof can be found from experience using many types of specialized detectors and different compounds. The literature is filled with examples, but the easiest way to see examples would be to search for HPLC-ELSD based methods). To ask 'why' instrument vendors include various curve fit options in their software does not address an actual need, but a perceived one. IN the case of curve fits, the DATA determines which fits are appropriate (not the vendor) and we are fortunate that so many chromatography software vendors have continued to include and offer many different types, similar to what is found in good quality statistical software packages.
I never stated that Linear output should always be used. I stated that you should use the best fit, the best formula that describes the data. This is not an opinion, but the mathematical model used to describe a data set.
Regarding calibration of mixtures. This has nothing to do with them all coming in the same vial. It is about measuring the response obtained from EACH sample or standard (which is not related to them being in the same vial. That is concentration, not response). We calibrate and fit points based on response. Two different proteins with the same concentration in solution can have two different responses (e.g. depending on the detector used), and this is why we measure it, record it and then plot it for each compound.
  • asked a question related to Chemistry
Question
6 answers
according to you what are Hot problems currentlyworld is facing? And what solutions you would suggest to solve them?
Relevant answer
Answer
  1. Now, I agree with prof. Madhukar Baburao Deshmukh.
  • asked a question related to Chemistry
Question
3 answers
chemistry webinar certificates
Relevant answer
Answer
The research knowledge shared during the webinar is much more significant .It also extend your CV and during promotion it will be helpful.
  • asked a question related to Chemistry
Question
8 answers
Dear Colleagues,
I’m pleased to inform you that open access journal /Catalysts/ (ISSN 2073-4344, Impact Factor: 3.444) is planning to publish a Special Issue on the topic of "Trends in Catalytic Advanced Oxidation Processes". The submission deadline is 30 March 2020.
This Special Issue is dedicated to novel achievements in the field of catalytic advanced oxidation processes. The contributions should be related to the listed topics:
· Catalytic processes in water and wastewater treatment
· Developments in Fenton-like AOPs
· Activation of Persulfates for AOPs
· Formation of sulfate radicals
· Catalytic cavitation-based AOPs (hydrodynamic cavitation and acoustic cavitation)
· Sonocatalysts
· Catalytic ozonation
· Photocatalysts—including visible light and UV applications
· Catalytic wet air oxidation (CWAO)
· Catalytic–electrochemical AOPs
· Carbon catalysts for AOPs
· Nanocatalysts
· Risk of by-product formation during water and wastewater treatment
· Developments in process control of catalytic AOPs (analytical methods, chromatographic, and spectroscopic techniques)
· Methods of catalysts characterization
· Post-process assessment of effluents toxicity
· Application of nanobubbles in AOPs
· Economic analysis of catalytic AOPs application and catalysts life cycle assessment (LCO)
· Industrial catalytic wastewater treatment
· Modelling and optimization of catalytic processes
· Green chemistry aspects in catalytic water and wastewater treatment
Detailed information regarding this issue, please follow the link below to the Special Issue website at: https://www.mdpi.com/journal/catalysts/special_issues/catalytic_aop
By publishing with Catalysts, you will take advantage of the following attributes:
*Fast Publication*:
First decision provided to authors approximately 13.4 days after submission; acceptance to publication is undertaken in 5.5 days (median values for papers published in this journal in the second half of 2018).
The papers will be processed immediately upon receipt. A Special Issue (SI) is not an issue of the journal. It is a collection of articles on a common topic. These articles are published in the regular issues of the journal when they are accepted (no delay) but additionally labelled with the Special Issue name (including a link). A single click on the link will organize all the articles on the Special Issue webpage.
*High Impact*:
According to Web of Science data, the impact factor for Catalysts 2018 was 3.444. The five-year impact factor was 3.808. Catalysts now ranks in Q2 of the "Chemical, Physical" category.
According to Scopus data, the CiteScore for Catalysts 2018 was 3.85, which ranks it in Q1 of the “Chemistry, Physical and Theoretical Chemistry” category, and Q2 of the “Chemical Engineering, Catalysis” category.
*Low Article Processing Fees*:
To enable the journal to make all of its content open access, Catalysts levies an article processing charge (APC) of CHF 1600 for each manuscript accepted after peer review in 2019 which compares well with other journals.
Please note that for papers submitted after 31 December 2019 an APC of 1800 CHF applies.
*Discount*:
A discount may apply if your institute has established an institutional membership with MDPI. For more information, see http://www.mdpi.com/about/memberships.
If you have helped review for MDPI journals and got a discount voucher, you can use it.
In order to plan for the whole paper project, I appreciate you could inform me within three weeks as to whether you would be willing to contribute. I also encourage you to send a short abstract to me (grzegorz.boczkaj@pg.edu.pl) or to Caroline Zhan (caroline.zhan@mdpi.com) in advance.
Sincerely hope this invitation will receive your favorable consideration.
Best regards,
Guest Editor
Prof. Grzegorz Boczkaj, PhD. Sc. Eng. Assoc. Prof.
Department of Process Engineering and Chemical Technology, Faculty of
Chemistry, Gdansk University of Technology, 80-233 Gdansk, Poland
Caroline Zhan
Assistant Editor
Relevant answer
Answer
Thanks for your invitation. We can contribute if publication charges are waived.
  • asked a question related to Chemistry
Question
3 answers
Polyhalite is a multi-nutrient source, its application assume to be changes the soil biology and nutrients chemistry on long term basis
Relevant answer
Answer
The chemistry would help respondents
  • asked a question related to Chemistry
Question
9 answers
Hey scientists,
I am just wondering what functional groups can be added to a hydrophobic molecule to make it water soluble at basic pH?
As a case study, let's just consider ethyl benzene as the scaffold. Not very soluble in water.
How can we make it soluble at basic pH? But extending functional groups to the carbon chain.
I know for instance, that you can have ethyl benzene. It can be made soluble at acidic pH by adding an ammonium chloride group. If you could convert ethyl benzene to phenethylamine by adding an amino group to the carbon chain then you got ethyl benzene. Still not very soluble. But if you react phenethylamine with HCl then you group phenethylamine-HCl or phenethylammonium chloride which is very water soluble at pH less than or equal to 7.
If you had ethyl benzene, what functional group could you add to make it soluble at basic pH?
I think that if ethyl benzene if we added a COOH group to the carbon chain we would have 3-Phenylpropanoic acid . If we reacted NaOH with that we would have 3-Phenylpropanoate Sodium Salt which I predict would be soluble at basic pH.
Is that correct? What other functional groups could I add to ethyl benzene's carbon chain to make the molecule water soluble at basic pH. Are there any functional groups that I could add to the carbon chain of ethylamine to make the molecule water soluble at basic pH and also positively charged? Like for example phenethylamine-HCl is positively charged but only soluble at acidic pH.
Relevant answer
Answer
Anything that would have a charge at basic pH, such as phosphate, sulfate, carboxylate, or tetrazole would help with solubility, but these are negative charges, of course. A quaternary ammonium group has a positive charge.
  • asked a question related to Chemistry
Question
4 answers
In experimental, the bond energy per atom rises quadratically with the number of bonds then why in simulations this bond energy per atom rises linearly with the number of bonds per atoms?
Relevant answer
Answer
I will get back to you soon.
  • asked a question related to Chemistry
Question
6 answers
dear friends, what is the most suitable iron complex to work with photo-Fenton without needing to stabilize the pH between 2.5 and 3?
I would like to work with the reaction at a pH between 4.5 and 6, would it be possible using some iron complex? like for example ferrioxalate?
Relevant answer
Answer
In the paper, "Heterogeneous photo–Fenton treatment for degradation of indigo carmine dye ". Cosme-Torres, et al., MRS Advances © 2019 Materials Research Society DOI: 10.1557/adv.2019.451 . 23 de febrero 2020. https://www.cambridge.org/core/terms,
you can read about this topics
  • asked a question related to Chemistry
Question
3 answers
Could anyone suggest me some good papers which involves the coating or mixing of MXenes with conductive polymers such as PEDOT or PANI or any other conductive polymer for that matter.
Relevant answer
Answer
Dear Lokesh Murali, by in-situ polymerization, you can easily solve MXene and aniline in the same solutions, then mix them by ultrasonication, and next initiate polymerization with dropwise addition of APS. the following paper is the same approach for PANI and clay layers:
  • asked a question related to Chemistry
Question
3 answers
Suppose you have a mixture mostly comprised of saturated fatty acids of carbon chain length C10-C20. Is there a process to convert them to unsaturated fatty acids?
The opposite process is well known. Margarine is produced via hydrogenation of unsaturated fatty acids to obtain saturated fatty acids. Is there something like a dehydrogenation process for saturated fatty acids?
If this process is feasible, could it be done in a targeted manner to yield mostly Omega-3 and Omega-6 fatty acids?
Relevant answer
  • asked a question related to Chemistry
Question
3 answers
Hi Research Gate,
A little background first: I'm a physicist, and I've done most of my work studying how chemical reactions move when they're pushed around by fluid flows. The trouble with this is I'm very limited because I don't know a lot of chemistry. I understand chemistry when I see it, but need to have a reaction identified before I can start trying to understand it. What this means is I have done most of my research on a single chemical reaction (The Belousov-Zhabotinsky reaction). The interesting phenomena around the BZ reaction, weren't my focus though, it just happened to be a reaction I knew how to make and that I could easily watch with a camera. However, I now want to go a little deeper into what's happening and the complex chemistry of BZ just gets in the way of understanding.
So I am asking you all if anyone has a suggestion for some interesting chemical reactions. For now I'm especially looking for reactions that 1) occur in the aqueous or liquid phase (so they can flow but are easy to contain) 2) Will sit inert until activated (now ideally I'd like the reaction to be completely mixed but need a catalyst to start an autocatalytic reaction, but I'd also take reactions where nothing happens until the second ingredient is added).
I'm also especially interested in reactions where it's easy to visually tell one state of reaction from another (say using an indicator dye). It would also be good if I could make the reaction from pretty standard chemistry supplies. Lastly I'd of course like reactions with practical import, say if the reaction makes something useful.
I know it's quite a list of things, but I'm hoping some helpful chemists (or even high school chemistry teachers really. As I said I'm not an expert on chemistry), are willing to pitch some suggestions.
If it's a reaction you study but don't want to deal with fluid dynamics on, great! I'm plenty willing to talk about what I'm trying to do.
~Thanks for reading, and hope you can help!
Thomas
Relevant answer
Answer
Well, if I were you, I wouldn't "mix a chemical reaction", just a reaction mixture. I wouldn't "move a chemical reaction" either. The chemical reaction also cannot be "pushed around by fluid flows" or "flow". Unfortunately, there are more awkward or incorrect phrases in your text. It is clear that you are a physicist and not a chemist.
  • asked a question related to Chemistry
Question
3 answers
I am following this recipe for PBABr synthesis. I added HBr (48 wt % in H2O) to Methanol and PBA solution at 0 degrees celsius. But after 2 hours of stirring I am not able to see precipitates. I have to evaporate the solution at 50 degrees celsius to obtain precpitates, I did that and still did not see any precipitates. Please help me with this. Thanks in advance!
Relevant answer
Answer
Dear Jitesh Pandya, please check the attached file and the references therein. My Regards
  • asked a question related to Chemistry
Question
6 answers
Not another chemistry Nobel going to biologists!’ How many times have you heard that complaint? But is there really anything in it?
It’s sometimes said that the number of chemistry prizes awarded to work rooted in the life sciences – at least nine of the prizes since 2000 – simply shows how broad chemistry is: at the molecular scale, biology is chemistry. But does that argument stack up? A historian of chemistry and a mathematical chemist argue in a new paper that, not only have the chemistry Nobels indeed become more biological in recent decades but also the prizes of that nature tend to reward work outside of the chemical mainstream, being much more closely tied to research in the life sciences itself. In effect, they say, the chemistry Nobels are being shared out between genuinely different disciplines.
Relevant answer
Answer
Recall that the award goes to someone that made a discovery with significant impact. The MRI for medicine, Black Holes for Physics, past organic chemistry discoveries for Chemistry, etc their is now a bit more a blur between physiology/medicine and chemistry. In the past so much was still being discovered in chemistry but now discovery is being made but the award is not for just discovery but for knowledge and impact. So the lines blur for medicine and chemistry. We find discoveries in chemistry that impact medicine and have real world impact. So the cheap answer is that the lines are blurring and utility and impact are becoming felt in society thus making an argument for the justification.
  • asked a question related to Chemistry
Question
1 answer
There are many research in field of "Transport in Porous Media" which is applicable from CO2 storage to chemistry engineering.
I like to collect more information on
What is going on right now in researching in this field?
And which areas in this field has remained untouched yet?
Relevant answer
Answer
Previous studies are mostly using default commercial codes for their modelling, perhaps developing your own code for a specific model could be useful for future studies.
  • asked a question related to Chemistry
Question
6 answers
I got a silicone substrate and I coat it with a conductive polymer.
But the conductive polymer doenst adhere very well, I did a crosscut test and the conductive polymer fully detached.
Which possibilities do I got to improve the adhesion?
Thank you.
Relevant answer
Answer
Try to use processing in HMDS (hexamethyldisilazane). For photoresists it work well.
  • asked a question related to Chemistry
Question
14 answers
Hello Good day i am a undergraduate student, please help me to have a topoc of my research proposal about organic chemisty. Thank you so much.
Relevant answer
Answer
Research proposal in Organic chemistry some more topics I want to suggest 1)Microwave assisted synthesis of heterocyclic compounds
2)Extraction of the plant products and their biological activity
  • asked a question related to Chemistry
Question
4 answers
I've already checked solubility of sodium chloride (NaCl) in water(20℃).
According to the solubility data, 359 grams of sodium chloride should be dissolved in 1 L water.
so I put 245.2 grams of sodium chloride into 1 L water and let the mixture into the ultrasonic cleanser and shaking plate for minutes, but It doesn't dissolve well. I can even see that the powder is deposited.
I want to make a sodium chloride solution with a concentration of 245.3g/L.
Can you tell me what the problem is?
Relevant answer
Answer
Please note that sodium chloride solution with a concentration of 245.3g/L is not to be obtained by dissolving 245.2 grams of sodium chloride into 1 L water. Instaed 245.3g of NaCl should be dissolved in somewhat less water, in a volumetric 1L flask, after that filled up to 1.000 L of solution.
  • asked a question related to Chemistry
Question
8 answers
They've invited me to publish and to become a reviewer/editor.
Relevant answer
Answer
The journal ”International Journal of Pharmacy and Chemistry” is published by SciencePG (or Science Publishing Group) which is listed in the Beall’s list of potential predatory publishers:
This is an important red flag. Other red flags are:
-In the indexing info no serious indexing in fact for example “Directory of Research Journals Indexing (DRJI)” is an example of a misleading metrics: https://beallslist.net/misleading-metrics/
-Misleading location: ‘office’ is USA is a virtual office (something predatory publisher often use to suggest another location than the real location Pakistan)
-See for numerous examples of predatory features of this publisher: http://flakyj.blogspot.com/2017/01/science-publishing-group-sciencepg.html
So better to avoid.
Best regards.
  • asked a question related to Chemistry
Question
4 answers
I'm an intern in a big company which makes flexible polyurehane foam for the automotive sector and I'm working on sound absorption properties of PU foam. I'm not chemist so I'm trying to improve these properties only by modifying process parameters.
Relevant answer
Answer
Dear Alvin Kissoondoyal, if it has such a shielding effect it will help and contribute in sound isolation. The main effect is that of PU bulk structure. My Regards
  • asked a question related to Chemistry
Question
4 answers
ANSYS or ABAQUS donot correlate materials chemistry wirh the observed or simulated mechanical properties. Is there a software that can do this structure to property correlation. ?
Relevant answer
Answer
I will recommend COMSOL Multiphysics . It does take care of chemistry and mechanical properties
  • asked a question related to Chemistry
Question
5 answers
I'm working on counter electrode for DSSC application, i would like to know if the CoSe can be doped with a MXene like Ti3C2Tx.
Relevant answer
Answer
Dear Lokesh Murali please see this useful article entitled MXene supported CoxAy (A = OH, P, Se) electrocatalysts for overall water splitting: unveiling the role of anions in intrinsic activity and stability
  • asked a question related to Chemistry
Question
5 answers
Hi, everyone.
Our lab is going to use ISO 12966-2 and 12966-4 and there is one moment in sample preparation (rapid transmethylation method under alkali-catalysed conditions) that I can't understand. It is about the addition of saturated sodium chloride solution after transmethylation reaction. Maybe I'm not so good in chemistry to understand the purpose of this action. So, can anyone please help me to get it?
Relevant answer
Answer
In the same way of Moosa Faniband, when you add NaCl, to aqueous phase become more polar, changing the partition coefficient. So, the analyte will be push to organic phase, increasing concentration in isooctane.
Hope helps
  • asked a question related to Chemistry
Question
53 answers
Considering the context of the COVID-19 pandemic that requires remote teaching activities. In the case of Chemical Education, which requires a high degree of abstraction and the use of visualizations can effectively contribute to the student's learning process, how does the teacher deal with the relationship of macro, micro and symbolic representations, in online teaching?
Relevant answer
Answer
I think that the teacher can use some applications that are online intended for learning the nomenclature, elaboration and spatial representation of molecules. There are also reaction simulators and laboratory practices where through color change you can explain and discuss with students the causes of a color change or a gas release. Also the teacher and students can make representations through animation programs that are useful to represent (model) some change or transformation of the matter.
  • asked a question related to Chemistry
Question
6 answers
Is is possible to find out if a material can function as a cathode or anode by just looking at cyclic voltammetry.
Relevant answer
Answer
Hi Lokesh,
Can I ask more about your goals with this project? You can in principle get almost any conductive material to act as either a cathode or an anode based on the potential you apply to that material, so long as you have a counter electrode to facilitate the closure of the circuit. The question is how good of an anode or cathode your material is, and that will largely depend on what reaction you want to occur within that material or at its surface.
To give a concrete example - and sorry here if I am using a different sign convention (these things can be tricky, but I come from a U.S. Chemical Engineering background): if I apply a cathodic (negative/reductive) potential to a platinum electrode in a conductive aqueous solution, I'll drive a net cathodic/reductive reaction (such as hydrogen evolution). If I apply an anodic (positive/oxidative) potential to that same platinum electrode in that same aqueous solution, I'll drive a net anodic/oxidative reaction (such as oxygen evolution). And if I have two platinum electrodes in the system at the same time, then one can act as a counter to the other; one will drive hydrogen evolution, and the other, oxygen evolution. There is nothing different about the electrodes or the solutions they are in, except the fact that I am controlling the relative potentials of the electrodes through the input of energy into a potentiostat (or similar device). Note: this is an electrolytic example, but I'm happy to discuss things from a galvanic cell perspective if that is more useful.
Best wishes,
Kindle
  • asked a question related to Chemistry
Question
9 answers
For our research subject in high school, we are required to conduct a research that can be done at the safety of our homes. Does anyone have any suggestions on what kind of topics we can research on? Thank you!
Relevant answer
Answer
When I was in high school I did an experiment on 3 different light colours (red, blue and green) and their respective effects on green bean plant growth. You can try this experiment using different light colours or different plants.
Or you can conduct a research on the effects on soil pH on plant growth.
  • asked a question related to Chemistry
Question
10 answers
Dear Chromatographers,
This method was developed on LC MS/MS. The quantifier for both analyte and internal standard have same product ion, will that have an impact on overall analysis. Any supporting article to read more about this would be very helpful.
Thanks
Relevant answer
Answer
Hi,
For those having a cross-talk problem, it is better to choose the deuterium or carbon isotope dilution method for internal standard (IS) quantitation. If you cant provide the isotope synthesized molecule or co-elution exist and you cant improve the chromatographic resolution then I strongly suggest switching your IS with an analog molecule, which behaves like your target compound (Extraction yield, ionization suppression effects etc.) but also giving fragmentation product at different MW far away from your target fragments.
  • asked a question related to Chemistry
Question
5 answers
As you know, a time crystal shows oscillations with a period longer than the driving force. Is it possible to use this feature in molecular machine synthesis? Does this provide any advantages to molecular machines?
Relevant answer
Answer
Thank you so much for pointing out the article, Dear Cüneyt Altındaş.
I see that it is related to a time symmetry breaking state and that there were two possibilities, classical and quantum time crystals.
I will try to understand the idea of the classical time crystal. The authors point out two simple hamiltonians, with broke spatial and inversion symmetry. They find some lagrangians that would be interesting to compare to the lagrangian of isotropic crystals.
  • asked a question related to Chemistry
Question
3 answers
I got the idea from using filters and other filtration systems in previous research experiences, and also how recently... someone gave me a bunch of Monster Energy drinks but they aren't sugar free so it got me thinking how it would be possible to extract the sugar from the Energy Drinks mechanically.
Sugar molecules are 1nm in size
salt (NaCl) is .06nm in size and water molecules are .275nm in size.
Would this work as planned or is there something my reasoning has a huge gap in? :)
Relevant answer
Answer
Not possible it is in dissolved state. You need to use evaporative crystallizer
  • asked a question related to Chemistry
Question
8 answers
Practical assessment method in chemistry Lab
Relevant answer
In my opinion, no. as far as practical examination is concerned there is need to analyze the student capability in chemistry.
  • asked a question related to Chemistry
Question
3 answers
Hello,
Cetyl alcohol is soluble in solvents like acetone and alcohols but not water. Cetyl alcohol is a waxy substance at room temp with a melting temp at around 50 dC.
If I want to dissolve cetyl alcohol in a solvent at room temp, will it dissolve? Or do I need to heat the mixture to CA melting temp?
Originally, I was thinking I would have to heat it. But then I thought there are substances that are solid at room temp but still have the ability to dissolve at room temp...
Thank you.
Kind regards,
Lara.
Relevant answer
Answer
Brilliant, thanks for confirming!
  • asked a question related to Chemistry
Question
7 answers
I bought G4 PAMAM dendrimer from a company but they aggregated. The size of them changed from 5nm to 100nm and I cannot work with them because the NH2 functional groups of dendrimers are not available for a chemical reaction. Please guide me, how can I separate PAMAM dendrimers? Is there any pretreatment?
Relevant answer
Answer
Dear Zahra Nazemi, you can break down aggregates by sonication, but you should first check literature for possible degradation. My Regards
  • asked a question related to Chemistry
Question
6 answers
Hello researchers,
Relevant answer
Answer
What equation? Do you mean the Michaelis-Menten equation? They can be determined graphically on the basis of the V = f (cS) curve, or can be calculated using, for example, non-linear regression.
  • asked a question related to Chemistry
Question
122 answers
Indeed, I have observed that there is some scientific journals that listed in Scopus sources of not good quality from scientific point of view. At the same time some Universities are depending on Scoups in a similar manner to that of Thomson & Routers or Clarivate analytics.
Relevant answer
Answer
LanguagesEnglishAccessProvidersElsevierCostSubscriptionCoverageDisciplinesLife sciences; social sciences; physical sciences; health sciencesTemporal coverage2004–presentGeospatial coverageWorldwideNo. of records69 millionLinks
  • Website
  • Title list
  • asked a question related to Chemistry
Question
4 answers
I am writing my thesis about metabolomics, and after reading about metabolites and proteins and how these have been measured through time for characterization and kinetics, I think metabolomics could be the one analytical technique that enables universal measurement of all intracellular, and possibly extracellular molecules. Even proteins with intact protein mode, for example. Maybe I'm too naive and inexperienced, and saving for some differences to enable separation (column chemistry), and ionization (ESI v APCI v direct injection), what are your thoughts on this statement?
Relevant answer
Answer
Hi Luis, metabolomics studies the metabolome in a top-down, experimental manner. The metabolome comprehends the whole ensemble of small molecules, with grey limits within biological oligomers. Proteins, genes, transcripts, are not part of the metabolome, neither lipids or glycans in my opinion. While MS or NMR can/will 'virtually' be able to obtain information about any molecule, for sure it will not be in a high-throughput manner, measuring everything at the same time. In fact, metabolomics is the least high-throughput omic technique where robust bioinformatic pipelines are still under development when compared to proteomics, genomics, etc. Many analytical techniques are 'the true' technique to answer the problem to which the technique is focused to retrieve data valuable to be evaluated.
  • asked a question related to Chemistry
Question
16 answers
kindly give the software details and download link
Relevant answer
Answer
Endnote
Mendely
Origin
ChemDraw
Docking
Rstudio
Matlab
there are many soft wares, it depends on your work.
  • asked a question related to Chemistry
Question
7 answers
As a requirment in my project, I have to synthesize Formamidinium bromide (FABr). According to the protocols which are mentioned in the articles, I've synthesized this material but I think there is an error in my work?
Does anyone has the experience of this synthesis?
Because in the articles, the authors don't express all the steps, I want to know if there is any critical strategy during the synthesis of FABr and specially in the purification stage of this process.
I would appreciate if you point out a reliable article which has mentioned all the stages of this synthesis with it's details.
Relevant answer
Answer
Dear Reads Nima Tabatabaei Rezaei,
Have you tried the way I propose to go ahead for the same? Just try it.Somebody has done and successfully got some very interesting synthesis results.
Because of the good thermal stability and superior carrier transport characteristics of formamidinium lead trihalide perovskite HC(NH2)2PbX3 (FAPbX3) has been considered to be a better optoelectronic material than conventional CH3NH3PbX3 (MAPbX3). The FAPbBr3 photodetector’s responsivity to two-photon absorption with an 800-nm excitation source can reach 0.07 A W−1, which is four orders of magnitude higher than that of its MAPbBr3 counterparts. Materials such as Formamidine acetate, lead bromide (PbBr2, > 98%) and hydrobromic acid (48 wt% in water), Gamma-butyrolactone (GBL) and N,N-dimethylformamide (DMF) may required for synthesis.
Formamidinium iodide (FAI) and formamidinium bromide (FABr) can be synthesised by dissolving formamidinium acetate powder in a 2x molar excess of 57%w/w hydroiodic acid (for FAI) or 48%w/w hydrobromic acid (for FABr). FABr can be synthesized by slowly dropping 10 mL hydrobromic acid into 50 mmol (5.205 g) formamidine acetate in a flask, accompanied by continuous stirring at 0 °C for 2 h under argon atmosphere. The product FABr was formed once the solvent was removed using a rotary evaporator at 70 °C. The crude white powder was dissolved in ethanol and subsequently reprecipitated in diethyl ether. Then, the filtered product was dried at 60 °C in a vacuum oven for 24 h for further use.
Ashish
  • asked a question related to Chemistry
Question
4 answers
Hello,
I need to impregnate the pores of a MOF with cu(acac)2, which I will then reduce under vacuum to copper nanoparticles. I plan on using the incipient wetness approach to do so. However, my MOF will not be in a powder form, but rather a self supported, fibrous mat form ( ). According to my current research, the solid support catalyst (MOF) is typically stirred as the metal precursor solution in chloroform (or other solvent) is added to it, yielding a paste. However, I cannot stir my fibrous mat. Will simple immersion of my mat in the metal precursor solution be sufficient to impregnate the pores of the MOF with the precursor? Or would a drop-wise method of adding my solution work without stirring the MOF? Is there another way around this issue?
Thank you for any answers!
Relevant answer
Answer
Claire Boyer I think that simply soaking the fibrous mat in a solution of Cu(acac)2 in dichloromethane over night will be sufficient to impregnate the pores of the MOF with the copper precursor. As suggested earlier, use dichloromethane instead of chloroform to dissolve you Cu(acac)2.
P.S. When other RG members help you by answering your questions, it is polite and a good practice on RG to recommend their answers.... 😎
  • asked a question related to Chemistry
Question
5 answers
Does anyone know of, or use, commercially produced surfaces for contact measurements (control material)? As an example, is there a producer of PTFE discs with highly controlled surface roughness and chemistry that I can purchase? I have not found any....
Relevant answer
Answer
Dear Michael Pujari-Palmer, why don't you use directly AFM for contact measurement? My Regards
  • asked a question related to Chemistry
Question
8 answers
I am wondering why some stains do not work by themselves and absolutely need to be paired with a counterstain to work. What is the chemistry behind this process? Is there a nice book that explains this process in depth?
Thank you very much for your answer in advance.
Relevant answer
Answer
Hi Alida, this is a really good question. I think that the basis for this is the combination of basic and acidic dyes to stain acidic/basophilic, and basic/acidophilic molecules in tissue, respectively. I realize that your question is really asking why some stains won't work without their counterpart. I know that you must use basic dyes before acidic dyes, and alcohol before aqueous, otherwise staining will not work. I suggest Animal tissue techniques (A Series of books in biology) 3rd ed. by Gretchen L Humason. It was published in 1972, but is still one of the best histology books I've ever seen. You can get it on amazon for about $10, ISBN-10: 9780716706922 .
  • asked a question related to Chemistry
Question
26 answers
Hi,
I tried the hummer's method with the steps mentioned below but the FTIR didn't showed peak for GO it only showed the peaks of graphite and other impurities groups. What could be the possible reasons for absence of GO formation?
My steps of hummer's method:
1) Poured 2g graphite flakes in 50 ml H2SO4(98.5%conc.) and stirred it. The temperature was kept below 5 degrees celsius.
2) After some minutes of stirring 2g NaNO3 was added to the solution and the solution was stirred for 2 hours.
3) Now 6g KMnO4 was added to the solution very slowly and temperature was maintained below 15 degrees celsius.
4) The ice bath was removed and the solution was stirred at room temperature for 48 hours. Actually the hot plate was not working properly so I was unable to set its temperature at 35 degree celsius. The temperature of the solution was some what 38 degree celsius when I checked it with thermometer. The colour of mixture changed to dark brownish and I observed that due to viscosity the stirrer was only able to rotate (stir) the mixture from center and thick mixture was sticked to the wall of flask.
5) After 48 hours of stirring 100 ml of DI water was added to solution and temperature reached to 95 degrees.
6) After stirring a couple of minutes at 95 degrees I added 200 ml of DI water and temperature dropped from 95.
7) Again after some minutes of stirring I added 15 ml (30% H2O2).
yellowish colour was observed only at the top of mixture. Below the mixture was brownish.
8) The mixture was then left overnight.
9) For washing the mixture was centrifuged at 8000 RPM first for collecting the particles.
10) The mud like pulp was then washed two times with DI water and one cycle with mixture of 1/3rd methanol and 2/3rd DI water at 8000 RPM.
11) Sample was then dried overnight in petri dish at 80 degree celsius on a water bath.
Kindly guide me dear members what went wrong in the whole process.
Relevant answer
Answer
Hameem Habib You need to have a centrifuge machine. The machine which I had access to, can go up to 12000 RPMs. However, I centrifuged my material at 8000 RPMs. Something over 3000 RPMs can also work (with problems). But, I recommend 8000 to 10000 RPMs. Steps are as below:
1) Arrange centrifuge tubes.
2) Fill centrifuge tubes with your GO liquid mixture upto two-third. For example, if your centrifuge tubes have a capacity of 10 ml. fill them upto 6ml. All tubes must be filled with the same volume of mixture.
3) Now put centrifuge tubes in the centrifuge machine. Remember to place them in such a way that there is gap of one slot between any two tubes. Which means if machine has 6 slots for tubes, only three must be occupied by the tubes. This is to maintain equilibrium of load for the wheel when it spins.
4) Centrifuge the tubes for 15 minutes at 8000 RPMs.
5) Take out the tubes. You'll see brownish substance sticked at the bottom of the tube.
5) Take out the tubes. You'll see brownish substance stuck at the bottom of the tube.
6) drain the liquid at the top of the substance. Don't worry, substance will not fall off.
7) Now add remaining GO mixture in tubes and centrifuge again with same RPMs and time.
8) Repeat this process until all of your GO liquid is finished.
9) Now add De-Ionized (DI) water in the tubes. And remember to fill the tubes upto two-third.
10) Now shake all the tubes by hand (closing them with their caps) so that the GO substance settled at bottom gets mixed with the water thoroughly to form a mixture.
11) Again place tubes in the machine (remember to place them with the same gap) and centrifuge them.
12) After centrifuging drain the liquid at the top of the substance.
** This step will reduce the Ph of the mixture by reducing the HCL present in it**
13) Repeat step 12 until you achieve a neutral Ph (Ph of 8 would also work but please do some hardwork to achieve 7, I know it would require a lot of labour).
14) You can check the Ph of the liquid in the tube before draining it through a Ph paper or with the help of a Ph meter.
15) After a neutral Ph is achieved, use something clean to take out the GO from centrifuge tubes carefully.
Hope it helps. If you
  • asked a question related to Chemistry
Question
12 answers
I come across many reactions like A + B --> products.
How to consider "products" as a species and solve the kinetics in simulation/modelling, as such the reaction is unbalanced by logic of chemistry.
Relevant answer
Answer
That is the weakness of lumping: The mass balance of components requires information on the product composition, which is not accessible after lumping. One might use average values for the products, such as molar mass or density. Those average values, however, depend on the composition, which is not known after lumping. The mass balance consequently contains errors. Therefore it is probably more meaningful to go for molar balances assuming constant density or flow rate (note that appropriate assumptions depend on the specific problem).
In general the applicability of lumping always depends on the accuracy required, which is defined in the problem statement. Therefore it has to be clear, which kind of assumptions are appropriate (e.g. constant density, flow rate, etc.). Furthermore, none of the products should affect the kinetics of the involved reactions.
Please also keep in mind that your question is rather generic and can't be answered in general, as the answer always depends on the specific problem.
  • asked a question related to Chemistry
Question
5 answers
Dear Scholars
I was wondering if anyone can recommend a publication on crude oil chemistry - particularly on SARA (Saturates, Aromatics, Resins, and Asphaltenes) classifications.
Thanks.
  • asked a question related to Chemistry
Question
13 answers
So I have some pH = {4, 7, 10} standard buffer solutions from Fisher Scientific. But they must have went bad or I must have contaminated them because when I try to calibrate my pH meter to 4 using the pH 4 standard buffer solution, it calibrates the pH meter to 2 which obviously isn't right because it should be 4 so I can't trust the standard buffer solutions!!!
I need to do some experiments which require that I accurately calibrate the pH meter which means I can't titrate the standard buffers with HCl or NaOH. I have to know the exact quantities. Might seem a little over-the-top, but I want to be really certain about the math.
I intend to prepare my own calibration standards using exact quantities of chemicals. Total concentration should be 0.1 M, volume needs to be 100 mL. I think 0.1 M is a good choice because that should have low ionic strength and not much crazy debye-huckel variations in pH.
I am pretty certain that I know how to prepare a pH = 4 standard buffer solution using acetic acid and sodium acetate. But I am not quite sure how to prepare a pH 7 standard.
First of all, is this exactly how I should prepare a 0.1 M acetate buffer in 100 mL?
According to pubchem the pKa of acetic acid is 4.76. I have a chem textbook which tells me that the pKa is 4.74. Not much difference so I will assume pubchem is right.
HA + H2O --> A- + H3O+
Acetic Acid + H2O --> Acetate + H3O+
Henderson-Hasselbalch Equation: pH = pKa + log([A-] / [HA])
pH = pKa + log([Acetate] / [Acetic Acid])
= 4.76 + log([Acetate] / [Acetic Acid])
For the total concentration:
[Acetic Acid] + [Acetate] = 0.1 M
The simultaneous solution to these equations is about:
[Acetic Acid] = 0.0852 M
[Acetate] = 0.0148 M
pH = 4.76 + log(0.0148 / 0.0852) = 3.9998 etc ... Pretty much exactly 4!
I have glacial acetic acid and sodium acetate.
Glacial Acetic acid is a pure liquid so its concentration is its density / (Formula Weight)
[Glacial Acetic Acid] = [(1.05 g/mL) / (60.05 g/mole)] * (1000 mL / 1 L) = 17.5 M
Basic Dilution Equation:
Initial Volume = (0.0852 M / 17.5 M) * 100 mL = 0.487 mL glacial acetic acid in 100 mL total volume.
Sodium Acetate --> Na+ (aq) + Acetate- (aq)
grams sodium acetate = (0.0148 moles sodium acetate / L) * (82.03 grams sodium acetate / 1 mole sodium acetate) * (1L / 1000 mL) * 100 mL = 0.121 grams sodium acetate
So I can exactly prepare a pH = 4 is 0.1 M acetate solution by adding 487 microliters of glacial acetic acid & 0.121 grams sodium acetate to 100 mL volumetric flask, and bring the volume up to 100 mL with ultrapure deionized water? Swirl to mix.
-----------------------
I am confused about how to prepare an exactly pH = 7 phosphate buffer solution.
I know the step wise dissociation of Phosphoric Acid. But the problem is that I am not certain about the second dissociation constant.
H3PO4 --> H2PO4- (aq) + H+ (aq)
H2PO4- (aq) --> HPO42- (aq) + H+ (aq)
If I know the second dissociation constant of phosphoric acid I could figure out exactly how to make a pH = 7 standard 0.1 M phosphate buffer solution using phosphate salts.
My undergrad general chem text book is telling me the second Ka is 6.2 * 10^(-8) or the pKa is 7.208 and pubchem is telling me the second the second pKa is 7.09.
Thus I could use the Henderson-Hasselbalch Equation again with the total concentration to figure out the exact quantities. But I am not certain about what the second pKa of phosphoric acid is! Are undergrad chem textbooks just wrong? That's too much of a margin of error.
pH = pKa + log[(K2HPO4) / (KH2PO4)]
Also I was wondering if a 0.1 M solution of NaCl would have a pH of EXACTLY 7? Would it be more or less accurate than making the phosphate buffer?
NaCl is formed by the titration of a strong acid HCl with a strong base NaOH. Therefore the equivalence point of the titration of a strong acid and strong base should yield a pH 7 of neutrality forming NaCl.
So if I dissolved NaCl in water to yield a 0.1 M concentration would the pH be just as good as making that phosphate buffer solution?
I also need to figure out how to make a pH = 10 standard buffer solution.
Any advice? Can you make my life easier?
Thanks so much!
Relevant answer
Answer
There must be some problem with the pH meter then.. U should show it to a technician so that it can be fixed.
  • asked a question related to Chemistry
Question
5 answers
#COVID-19
Coronavirus Covid-19: Current Research. Open Access Publications Chemistry in Coronavirus Research: A Free to Read Collection from the American Chemical Society
Relevant answer
Answer
Can have a look - on the attached manuscripts
  • asked a question related to Chemistry
Question
8 answers
I have extracted Manganese dioxide from zinc-carbon battery in order to prepare Manganese fertilizer . but it never dissolve , Why ??
Relevant answer
Answer
Please check the following link, I hope this can help:
  • asked a question related to Chemistry
Question
7 answers
I recently read:
"The perovskite solution for the solvent quenching method (MAPI) recipe was prepared by dissolving 553.2 mg PbI2 and and 181.23 mg MAI in 1 ml anhydrous DMF/DMSO (4:1, v:v) to obtain a 1:0.95 molar ratio solution (PbI2:MAI) with a concentration of 42.96 wt %."
How can one get 553.2 mg of PbI2 and 181.23 of MAI (CH3NH3I) to be dissolved in 1 ml solution to obtain a 1:0.95 molar ration solution when the molar mass for PbI2 and MAI are 461.01 g/mol and 158.97 g/mol respectively.
I am confused. Thanks for the help in advance.
Relevant answer
Answer
I highly agree with the opinion reported by Frank T. Edelmann
Regards
  • asked a question related to Chemistry
Question
4 answers
Some studies reveal that SARS-CoV-2 virus activity can be mitigated at the alkaline pH medium (above pH= 7.5). Any explanation about the mechanism or the Chemistry behind this phenomenon.
Relevant answer