The branch of chemistry concerned with identifying and quantifying the chemical constituents of matter.

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251 views

Why note the solvent level on chromatography paper when it is removed from the chamber?

Why is it important to mark solvent level on chromatography paper when you remove it from the chamber?
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15 views

Chromatography Separation Quantifying

This is a textbook question: "Suppose you are using chromatography to separate a mixture of two substances. Can you propose a means of quantifying how good or how poor the separation is?" So I got ...
3
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1answer
28 views

How to calculate mass of nanomaterial grown on a substrate

I'm growing graphene on copper substrates and need to know the mass. The graphene is grown via chemical vapor deposition; amounts of reactants are not completely known. The best approach I've thought ...
2
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1answer
42 views

How do I find the empirical formula for Co(C2O4)*H2O with mass of Oxalate and Oxide Product?

I have the formula $\ce{Co(C2O4)*H2O}$ in a reaction that forms cobalt oxide $\ce{Co3O4}$ – My data here says that my oxalate hydrate weighed 0.3283 g and my product oxide weighed 0.1158 g which I ...
2
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1answer
67 views

Near IR spectroscopy vs. IR spectroscopy

I am a backer of this Kickstarter: SCiO Near IR Spectroscopy Here is a link to their technology: SCiO Technology Question: How short of full IR spectroscopy do you think this device is? I have asked ...
2
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1answer
36 views

to convert ppm gas (N2O) concentrations in microgram nitrogen per gram dry soil basis?

What calculations are needed to convert $\ce{N2O}$ gas concentrations in ppm to micrograms of nitrogen per gram dry soil basis? I measured the concentration of $\ce{N2O}$ in soil samples. I extracted ...
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0answers
19 views

Determination of carbon content of steel by liquid chemistry

It seems like the typical laboratory methods for determining the carbon content of steel are to cuppellate it in a stream of oxygen and then measure the volume of the evolved $\ce{CO}$ and $\ce{CO2}$, ...
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26 views

Chemical Sensor Question [closed]

(a)You are assigned to develop the gas sensors for Mars mission. Please show me the pros and cons of at least 6 types of gas sensors for CO and ethanol. (b)Tell me which one you will pick for your ...
2
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1answer
24 views

Pb-based pigments and rhodizonate salts

In a previous question, I learned that we can detect lead with sodium / potassium rhodizonate, giving a nice purple color when reacting with pure (elemental?) lead. But in the paint, lead is ...
10
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1answer
70 views

Maximum observed optical rotation through a polarimeter

Is there a maximum optical rotation of plane polarized light that can be observed using a polarimeter? I understand that in a polarimeter, light passes through a filter that converts it into plane ...
7
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2answers
94 views

How to detect lead paint on a bicycle?

Recently I started renovating a bicycle. The frame has been painted probably over 30 years ago, and despite holding well, big patches of rust are showing. So it's time to give the bike a new paint ...
4
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1answer
95 views

What is the purpose of UV-VIS Spectroscopy?

I understand the purpose behind infrared spectroscopy and mass spectroscopy, but UV-VIS doesn't make much sense to me. Through research, I see that it has to do with electron orbitals, and it has a ...
10
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1answer
119 views

Phenyl group in proton NMR

Suppose you have this spectrum and the molecular formula of $\ce{C10H12O}$ The structure is My problem is with the peak at ~7 which is an H-Benzene signal, with quartet splitting and a relative ...
6
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1answer
148 views

How to analyze a acid and salt mixture using titrimetry?

Given a mixture of $\ce{HCl}$ and $\ce{MCl3}$ and the following dissociation constants for $\ce{M(OH)3}$, how can the concentrations of $\ce{HCl}$ and $\ce{MCl3}$ be determined separately by titrating ...
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vote
1answer
27 views

solution concentrations [closed]

I think I'm making this more complicated than it needs to be, but here it is: I have 7 drug solutions, all 1 mg/mL which need to have the following concentration in urine: A: 25,000 ng/ml B: 25,000 ...
2
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1answer
36 views

Role of Acetonitrile and Ammonium Acetate buffer in Leucomalachite Green stock solution?

I am trying to repeat an experiment conducted by FDA on Malachite Green (MG). According to this paper, ...
5
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1answer
35 views

How are hormone levels measured?

I have been searching google and didn't found any links that describes how this process is performed - I mean the chemical procedure, not the process of taking the blood from the vein.
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36 views

Fertiliser analysis - Why doesn't it show ureic nitrogen when it does have urea?

I have had two types of urea fertiliser analysed, the results are as follows: $\ce{46\%N}$ (46% nitrogen) - which is sold as a urea fertiliser, tests at 46.1% ureic nitrogen. $\ce{38\%N 19\%S}$ (38% ...
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0answers
35 views

Choosing the instrumental techniques for chemical analysis [closed]

Since every technique has its goods and its bads characteristics, it's a bit hard for me to choose between them to determine specific elements, methods such as UV-VIS spectroscopy, IR spectroscopy, ...
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14 views

Qualitative spectrographic analysis

In order to identify the presence of a specific element, one must identify at least three ultimate lines of that element in the specter. Those lines are the ones with the highest intensity. I ...
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20 views

Know any micropipettor that is acid resistant?

We pipet concentrated nitric and hydrochloric acids. our current pipettor is rainin lite but its piston is metal and thus corrode easily. We discussed this with our inhouse technician and he ...
2
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1answer
32 views

What is the mechanism for electrospray ionization?

I've been asked to Descibe the ionization mechanism used in electrospray ionization I know that this is a desorption ionization source, which uses a high electrical field as the ionizing ...
6
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1answer
83 views

Estimate the concentration of HCl and volume of 6 M HCl required to complete precipitate each of the given salts

In our chemistry lab we performed the following experiment below. Given that $K_\mathrm{sp}(\ce{AgCl}) = 8.2 \times 10^{-11}$ and $K_{\mathrm{sp}}(\ce{PbCl_{2}}) = 1.7 \times 10^{-5}$ ...
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3answers
121 views

What are some books, websites, etc. where I can find the detailed protocol for standardization of sodium thiosulfate with dichromate?

I am looking for a book or website such as "Vogel's Textbook of Quantitative Chemical Analysis" where I can find methods for analyzing/standardizing a particular species easily. I am not looking for ...
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2answers
46 views

2,4-dinitrophenyl hydrazine test

I found this reaction over here: which illustrates the carbonyl test but looks fuzzy. Assuming that the R in the product is a typo for H, I couldn't conserve the number of Nitrogen atoms. ...
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1answer
43 views

Is the following reaction redox? [closed]

Is the test of sulphur using sodium nitroprusside a redox reaction?
3
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1answer
28 views

Stability constant of complexes

I know that this constant tells us the strength of the interaction between the metal and the ligand, so should it also mean that the higher the constant, the stable the complex ? I need to make sure ...
4
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0answers
42 views

Different elution profiles of carvacrol and thymol

I have identified carvacrol and thymol via thin-layer-chromatography and via gas chromatography On a normal silica plate the thymol has a higher Rf-value then carvacrol. The explanation for this would ...
0
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1answer
48 views

Photometric titration

If we have $\ce{A + T -> P}$ where $\ce{A}$ is the analyte, $\ce{T}$ is the titrant, and $\ce{P}$ is the product, photometric titration happens only in one condition, that one of the following ...
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0answers
11 views

Optional determination techniques in AAS

I have tried to find information about this case but I couldn't find anything specific. The key point of instrumental methods of analysis, is for the student to be able to know which one of the ...
6
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1answer
44 views

Determination of mercury in AAS

Its known that the only method to determine mercury in atomic absorbtion spectroscopy is the cold vapor method. What is the reason that mercury can't be determined with other methods, such as flame, ...
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0answers
21 views

How to confirm the type of bonding taking place between two substances?

For example ink on paper: how can I confirm that the bonding is van der Waals and not covalent? Similarly, the same question can be asked about other interaction such as hydrogen bonding, ionic ...
3
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2answers
156 views

Converting g/L to mol/L

I know I should divide $\mathrm{g~L^{-1}}$ by the molar mass of the substance, but I don't seem to find the specific answer on Google. So just to be sure: If I have ...
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31 views

Atomizers in AAS

Electeothermal atomizer ( graphite furnance ) and flame atomizer, are the instruments which help us to convert the analyte into the gas state and they both achieve that. My question is, what's the ...
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80 views

Manuals for a Cahn TG-171 Thermogravimetric Analyzer

Recently a Cahn TG-171 Thermogravimetric Analyzer was donated to my school. We did not get a service or user's manual with it, and some of it still needs to be put back together. I have tried to ...
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1answer
70 views

How does standardising a secondary standard solution make it suitable as a standard solution?

I know that a standard solution in volumetric analysis must have an accurately known solution. Primary standard solutions (e.g. anhydrous sodium carbonate) can be used straight-away as they follow the ...
3
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1answer
71 views

Identify this solution

The solution is emerald green in colour. When added with water, it gives a pale blue solution When reacted with $\ce{BaCl2}$, it gives a sky blue solution and a white precipitate. When reacted with ...
7
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1answer
38 views

Wavelength extention in AAS

Theoreticly, the width of the spectral line in AAS (atomic absorbtion spectroscopy) is 10^-5, but in fact there happens an extention of it and it becomes 0.002-0.005. There are some factors which ...
7
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2answers
64 views

Way to detect lead in gasoline

Is there any way that i can detect lead in gasoline, not by sending of to a lab but to be able to do this by myself?
6
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2answers
169 views

How is drift due to static electricity eliminated from an analytical balance?

I've recently encountered a problem when using an analytical (0.1 mg accuracy) scale to determine the mass of a sample of ferrocene powder. The reading in the balance seems to drift either upwards or ...
2
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1answer
86 views

Auxochrome groups

Functional groups like $\ce{OH}$, $\ce{NH2}$, attached to nonsaturated compounds (chromophores) are called auxochromes. These groups tend to shift the wavelength to the infra-red area which is called ...
3
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1answer
35 views

Derivation spectrum

My book doesn't seem to properly explain the importance of derivating the Gaus spectral line, neither the meaning of it, so my questions are : 1.What do the spectral lines of 1st, 2nd, 3rd and 4th ...
4
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1answer
37 views

Smith Hieftje correction method

I completely don't understand how this method works. My book says that this method works by the principle of self-absorption which occurs by the emitted radiation of hollow cathode lamp when it works ...
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2answers
59 views

Why are hollow cathode lamps used for atomic absorption spectroscopy?

In 1955, it was proposed that hollow cathode lamps are good emission sources for monochromatic radiation, and thus for atomic absorption spectroscopy (AAS). In looking into the topic, I've read that ...
3
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1answer
40 views

Instrumental methods of analysis

I am taking the instrumental methods of analysis course. Our job is to find the unknown mass of $\ce{Fe}$ which is added, by measuring the absorbance of different solutions with ortho-fenantroline. ...
6
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1answer
91 views

Comparing wt% to at% which is normalized to 100%

I have measured the element composition of a sample using ICP-OES, and reported my results in wt%. A study which has analyzed the same sample types, but with an electron microprobe, has reported their ...
2
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1answer
46 views

Spectral Peak-Picking in MS Excel

I'm working often with spectral data of various gases, and the bulk of the data analysis is assigning the peaks with maximum signal (y-axis) to frequency (x-axis). Often we have several thousand data ...
2
votes
1answer
57 views

Yeast Fermentation with YPD + Apple Juice

I am working on a project for my General Chemistry class. I am trying to compare the EtOH production (and the rate of EtOH production) between seven types of yeast strains by fermenting the YPD ...
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1answer
61 views

How to calculate the required concentration for sodium sulfite to remove oxygen as an oxygen scavenger from a solution?

If I know the amount of oxygen in such a solution, how can I know the required concentration of sodium sulfite to be used and react as oxygen scavenger?
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1answer
57 views

Spins spin coupling on proton NMR for an aldehyde?

On a proton NMR, does the hydrogen in the CHO group cause coupling, or get coupled itself? Specifically, I a considering 2-methylpropanal. I cannot decide whether the H in the aldehyde group would be ...