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

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2
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1answer
11 views

How does the Rf value change when changing the eluent composition?

A non-polar molecule X is analyzed by TLC chromatography on silica to determine its $R_f$ value. The first eluent was hexane:EtOAc = $9:1$ and the $R_f$ value was $0.5$. In the second run, ...
0
votes
0answers
8 views

Experiment with magnesium-sulfur fertilizer

This fertilizer for is for soil and plant growth, and I was thinking of doing an experiment with it. The bag says it contains magnesium sulphate and water soluble sulphur trioxide. Is there anyway to ...
1
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0answers
21 views
+50

What analytical method(s) to use for finding the contaminations in a fatty base material

In a large batch of a fatty combustible mixture there appear to be two contaminations, since after combustion there are 2 residues clogging up the injectors and exhaust system: - a calcium salt - a ...
0
votes
2answers
32 views

Need help identifying a soluble, olive green substance with an orange/yellow flame color

$\hspace{4.4cm}$ Working on identifying substances in a mixture. I have been able to find the identify of every other substance so far, but I am completely stumped on this olive green substance. All ...
1
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0answers
23 views

Which is more amphoteric: zinc or copper hydroxide?

$\ce{K_{a} ~Cu(H2O)_6^2+}{=~5*10^{-7}} $ $\ce{K_{a} ~Zn(H2O)_6^2+}{=~2.5*10^{-10}} $ Given this information, which forms a more amphoteric hydroxide? My reasoning is that copper hydroxide is more ...
8
votes
3answers
86 views
+500

How to separate and analyse a sample of cations of alkaline and earth alkaline cations and ammonium?

I am teaching a section of qualitative analysis and I am trying to get a better grasp on the assignments the students are doing. These are the cations they may be presented with and must identify: ...
0
votes
0answers
37 views

Sodium percarbonate and sulfuric acid reaction

If an excess sulfuric acid is added to a detergent containing sodium percarbonate, would it be possible for the excess acid to react with hydrogen peroxide? I believe that the hydrogen peroxide will ...
0
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1answer
27 views

Definition of drift

What does drift actually mean in analytical chemistry? I can't find the exact definition and now am not sure whether my intuitive understanding of it is correct.
3
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1answer
33 views

Validating a GC instrument / column

Are there any generic rules / heuristics to identify a good GC vs a bad one? The context is that during manufacturing-troubleshooting I often get shown GCs of various fine chemicals and I often ...
3
votes
1answer
34 views

Chromatography: Why does the insoluble compound get pulled along?

In paper chromatography, we see that a paper with an ink spot on it get dissolved in the liquid and travels up with water due to capillary action. Then the compounds with more affinity to the paper ...
0
votes
0answers
19 views

How to convert units of a molar concentration to a mass

I am trying to calculate a mass based on a molar concentration obtained after diffusion has occurred through a pore for a research project. I have the molar concentration of calcium chloride and am ...
0
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0answers
10 views

Software for ion speciation of Ni(II)?

How can I make an ion speciation curve of $\ce{Ni^{2+}}$ in a base solution $\ce{NaOH}$? Does there exists a software that does that or a tutorial? I tried using HYSS2009, but documentation is no good ...
-1
votes
1answer
44 views

Reactions of Phloroglucinol

Does phloroglucinol respond to the iodoform test? cerric ammonium nitrate test? 2,4-DNP test? I couldn't find any good sources that answer any of these. I thought of this: Tautomerism can ...
3
votes
0answers
45 views

The behaviour of Ag3PO4 in solution

To a 1L flask, we add $4.1900\mathrm{g}$ ($0.01001\ \mathrm{moles}$) of $\ce{Ag3PO4}$, then fill it up with water. Knowing the following constants, we are asked to find the concentration of all ...
2
votes
1answer
14 views

Quantitative Analysis of Urea in aq. solution

What would be a good way to assay Urea in aq. solution? The test doesn't need to be super accurate. 1% accuracy is fine. But it needs to be relatively fast & robust to carry out. NaHCO3 is a ...
3
votes
0answers
47 views

Apparent solubility of Ag2C2O4 in a buffer solution

We take the following quantities and mix them together: $20\mathrm{mL}$ solution of $\ce{AgNO3}$ $0.001 \frac{\mathrm{moles}}{\mathrm{dm^3}}$ $20\mathrm{mL}$ solution of $\ce{H2C2O4}$ ...
1
vote
1answer
38 views

What is the process to solve this disproportionation REDOX question?

I know how to solve REDOX reactions, but this one is really confusing me, since I can't really write half reactions for it. $\ce{ClO3- -> Cl2 + O2}$ the answer is apparently $\ce{2H+ + 2ClO3- ...
2
votes
0answers
20 views

How does pH level change the concentration of dissolved oxygen (DO) in sea water?

I am planning to investigate the relationship between $\mathrm{pH}$ and dissolved oxygen. I would like to have a reason without taking in account the plants, animals and decomposer roles. I want to ...
0
votes
0answers
9 views

electrophoretic mobility and EOF

I'm currently studying about capillary electrophoresis. I'm quite confuse about mobility of electrophoretic and EOF. Why does negative charge has greater electrophoresis mobility than EOF and ...
1
vote
0answers
25 views

How to test if white powder is lime fertilizer?

I found two buckets (white and black) containing a very light grey powder in the basement. The label is partially removed, but it probably originally contained lime fertilizer. However, I am not sure ...
5
votes
2answers
96 views

Remove salt from dirt

I have a mixture that contains out of dirt/sand and salt. I want to extract and measure the salt. What would be the best way to extract the salt from this mixture? P.s not sure if this is the ...
2
votes
0answers
31 views

Method and Tips for Inorganic Qualitative Analysis

In a few weeks time I will be doing a inorganic qualitative analysis test which is very pressed for time (a majority of people don't finish). The form of the test is most likely going to be that there ...
0
votes
0answers
37 views

What reaction distinguishes glycerol and tert-butanol?

What reaction can we use to distinguish between glycerol and tert-butanol in laboratory conditions? I know alcohols exhibit the following: deprotonation, yielding an alcoholate salt reaction with a ...
0
votes
0answers
14 views

Why -COOH group on the Graphene quantum dots have much more affinity with Hg(II) than other ions?

Could anybody explain why the COOH group around the edge of the GQDs have much more affinity with Hg(II) than others?
1
vote
0answers
21 views

What type of standard for HPLC capsaicin quantification?

I'm wondering which type of standard would be the most suitable for the quantitative analysis of capsaicin (8-Methyl-N-vanillyl-trans-6-nonenamide) containing products? Sigma offers the following ...
0
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0answers
28 views

Simplified Chromatography - will this work?

I am interested to separate a sample matrix via a method very similar to chromatography. The reason I am asking about this is because I am planning to integrate this method with my SERS application. ...
3
votes
1answer
29 views

Correct term/word for bias in calculations?

I ran an experiment recently and made several approximations in the calculations that led to the results being around 2 orders of magnitude less then the literature values. I will be re-doing the ...
1
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0answers
21 views

What means can be used to distinguish different sorts of plastic?

So, different sorts of plastic usually have different marks on them (the resin identification code, like 1/PET for polyethylene terephthalate etc). However, sometimes one can encounter a piece of ...
1
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0answers
32 views

Can we make chromatography less troublesome?

Thin Layer Chromatography is a very powerful method in analytical chemistry for separating complicated chemical matrices. As an engineer, I am interested to build device capable of automating TLC ...
1
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0answers
28 views

E / Z Isomers GC peaks for identification; Would GC-MS help?

Does a GC analysis typically seperate E / Z isomers? I'm reading a paper that confirms that the product it synthesized was indeed the (E,E) isomer by coinjecting a standard sample on the GC. My ...
0
votes
0answers
23 views

What is the difference between column chromatography and a fractionation column?

I'm a chemistry student doing research in a biotech lab. I'm doing the chemistry portion of the project. It is time to write the methods for my paper and I'm confused on what the proper term for what ...
1
vote
1answer
75 views

In NMR Spectroscopy why use absorption and dispersion components of the FID spectrum rather than magnitude and phase?

In chapter 4 of Dr James Keeler's book 'Understanding NMR spectroscopy' (http://www-keeler.ch.cam.ac.uk/lectures/Irvine/chapter4.pdf) he explains how to calculate the expected spectrum of a FID ...
0
votes
1answer
77 views

Minerals in water solidify when heated?

Is it possible for minerals in drinking water to solidify when high temperatures are applied? The minerals in mind are: iron, copper, aluminum, magnesium. Background: I have small, brittle, darkish ...
2
votes
2answers
134 views

The mathematical condition for a complete complexation reaction

I'm being asked to find the volume of a $\ce{NH3}$ solution ($0.1\ \mathrm{M}$) to be added to $10\ \mathrm{mL}$ of a $\ce{AgNO3}$ solution ($0.1\ \mathrm{M}$) to assure the 'complete formation of ...
0
votes
1answer
65 views

How to estimate the concentration of OH that comes from just the autoprolysis of water in a basic solution?

In my analytical chemistry course, a question reads: What is the pH of a 0.10 M solution of THAM? Is it valid to neglect the autoprotolysis of water? Justify and explain your answer by estimating ...
1
vote
0answers
40 views

Is there any process to determine what elements a physical sample is made from?

I'm wondering if anyone knows of laboratory services that can analyze a sediment sample to tell what it's made of. Background: our drinking water has small black flakes appearing, and our city water ...
1
vote
1answer
48 views

GCMS Peak Identification: Online or Open Source / Free Programs?

Suppose I have a GCMS peak graph for a component, what are possible options to figure out what the molecule may be? Any tips about good software that will do this? I do know that for many compounds ...
0
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0answers
12 views

White precipitate observed in bromelain assay

After adding TCA to bromelain assay, I was unable to measure absorbance for 2 days (which is not suppose to happen though), and now it has formed some white colour precipitate, and I vaguely remember ...
1
vote
0answers
21 views

concentration of silver nitrate solution [closed]

I have 300 litres of silver nitrate solution. From this I took 100ml solution. I need to get the concentration of this 300 litres of solution by titrating the 100 ml against pottassium chloride ...
0
votes
1answer
46 views

Formation of water vapour during combustion

When we burn fuel, water vapour is produced because hydrogen is burnt as well. But since the vapour is in gaseous state already, it shouldn't steal any heat from fuel gases, should it?
0
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0answers
45 views

Issues with visually determining the end point in redox titrations

This month, I have to practice redox and acid-base titrations for the Chemistry Olympiad, using reagents like: Sodium Thiosulfate ($Na_2 S_2 O_3$), Potassium Permanganate ($K_2 MnO_4$), Potassium ...
0
votes
1answer
66 views

Calcium sulphate soluble in water

In the volumetric estimation of calcium in a given solution as calcium oxalate.. We convert the calcium oxalate to oxalic acid by dissolving the former in hot (~70 °C) 2 N sulphuric acid solution. ...
3
votes
1answer
93 views

Analysis of multiple spectra to determine an unknown structure

I've been trying to solve the structure of a molecule from a 13C and proton NMR as well as a MS spectrum, but I've been stumped, I've been staring at it for a while with no improvement. I've attached ...
1
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0answers
30 views

How to calculate pH? [closed]

Could you please help me or give me any source to understand the calculation of pH in acid and bases both strong and weak ? And pH in salt solutions ?
4
votes
4answers
118 views

number of significant figures in 5*5.364?

How many significant figures should be present in the answer of $5\times 5.364$? 1) Addition rule: The result cannot have more digits to the right of the decimal point than either of the ...
6
votes
1answer
126 views

Which method can be used to determine the pKa of an acid-base indicator like bromothymol blue?

I have a question about how one would determine the pKa of an acid-base indicator such as bromothymol blue. I know that spectrophotometric analysis is one option, but is it possible to perform an ...
0
votes
2answers
36 views

What type of analytical chemistry (such as spectroscopy) is suitable for high resolution air analysis

I want to find some type of analytical chemistry method, such as spectroscopy, that is capable of analysis the chemical composition of air. If it can be used for high resolution analysis would be ...
1
vote
0answers
13 views

pH of a solution 1) disregarding activity and 2) using ionic activity coefficients [closed]

A weak acid with MW= 356 and pKa= 2.76 is dissolved in an isotonic NaCl solution to make a 3% w/v solution. What is the pH of this solution 1) disregarding activity and 2) using activity coefficients ...
-1
votes
1answer
50 views

Why does more acetic acid require more sodium hydroxide in order to be neutralized

I was recently titrating sodium hydroxide against vinegar and based off my results i realised that the vinegars with a higher concentration of acetic acid required more sodium hydroxide in order to ...
-1
votes
1answer
74 views

How to determine the molecular formula of a compound given percentages of the elements?

If the molecular mass of a compound is given as 'm' and it consists of two elements 'A' and 'B'. The compound it composed of x% of 'A' and y% of 'B'. How do I find the molecular formula of the ...