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

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The Principle of Internal Standardization (in the context of ion chromatography)

I am trying to grasp how internal standardization works in principle, and I am having some trouble wrapping my head around it. It is not the choosing of an IS I think about, orwhen it might benefit ...
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19 views

Find ratio of number of atoms of $A$ and $B$

However I am thinking of this question to be damn easy but still I'll not say as I am not getting it, There are two radio nuclei $A$ and $B$. $A$ is $\alpha$ emitter and $B$ is $\beta$ emitter ...
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12 views

Final amount of Hg present after $\beta$ decay

I have been trying to solve an exercise of Nuclear Chemistry, well I was not sure that whether I should I ask this on physics or chemistry but I think that if chemistry had an exercise based on this ...
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52 views

Interpreting the Infrared Spectroscopy(IR)?

I have already attempted to interpret some of the peaks. Please tell me if they are correct/incorrect and anything that I have missed. Thanks !
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23 views

What's the difference between Carvacrol and Thymol?

What is the difference when it comes to separating Carvacrol and Thymol on HPPLC with reverse phase - C18 column? Carvacrol elutes first, is that because it is ortho?
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19 views

How can I determine/quantify the presence of boron nitride on a metal surface?

We use micron-grade hexagonal boron nitride (hBN) to coat the surface of bullets that are jacketed in gilding metal. This coating is mechanically embedded/plated onto the surface in order to increase ...
2
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1answer
64 views

Mechanism for the Beilstein test?

What is a possible mechanism for the Beilstein test for halogens ? I can't seem to find a arrow pushing mechanism for this reaction.
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3answers
68 views

Mechanism for Tollen's classification test for Aldehydes?

I am trying to find a mechanism for the Tollen's Test online but only thing I am finding is balanced equation. Can someone propose or help me find the mechanism ? Thanks !
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1answer
61 views

Separation of Binary mixture?

I will be given a binary mixture containing two unknown compounds(the mixture could be either liquid or solid- I don't know yet). The plan of the experiment is to identify the two compounds. So my ...
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50 views

Interpretation of the following IR?

I have the following IR Spectrum that I am trying to interpret: So far I am thinking this compound have: a primary amine due to two peaks at 3624 and 3533. The sharp peak 3416 could indicate an ...
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97 views

$\ce{^13}$C NMR of dimethyl 3,4,5,6-tetraphenylphthalate?

I am trying to assign the peaks here to dimethylphenylphatalate but all the benzene rings are throwing me off. All I can get is that the further most signal is the carbonyl carbon (168.71) and the ...
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76 views

HNMR - Peak Splitting

If you have $\ce{CH3-\color{\red}{CH2}-CH2Br}$ Then the $\ce{CH2}$ (in red) would have a peak splitting of $12$ because $(n+1)(m+1)$ where $n$ for the $\ce{CH3}$ is $(3+1=4)$ and m for $\ce{CH2}$ is ...
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24 views

Determine Cu+2 and SO4-2 concentration using Potentiometry?

The title says it all. I've been researching as well but all I could come close was solid state ion selective electrodes. Could someone please help me out? There should be two methods(or one) to ...
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43 views

How to test purity of potassium nitrate?

What equipment should I use or what methods do I follow to correctly make a close approximation of the purity of potassium nitrate? I have already tried to use school equipment, but they did'nt even ...
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3answers
72 views

Easiest Test for Iodine

Most health-food stores carry supplements supposedly containing iodine for people with iodine deficiency. I recently bought some kelp tablets that are supposed to have iodine but as a consumer how can ...
2
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1answer
27 views

How to find trace methanol content in fermented fruit/distillate?

Suppose we have some fermented (optionally also distilled) fruit/fruit juice. The sample therefore contains water, sugars, ethanol etc. Which analysis method is the simplest to find out whether the ...
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47 views

How do i detect the compounds a plant is made of, automatically?

Let's say I want to take a random plant , and get the chemical formulas of the compounds he's made of. Is there an automated method for doing so and how costly is it(roughly) ?
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25 views

Calculate accelerating voltage required to separate two particles in a magnetic sector analyser

So, in mass spectrometry we have the following equation to describe a magnetic sector analyser, $$\frac{m}{z}=\frac{B^2r^2e}{2V}.$$ Lets say that I have two particles with different mass/charge ...
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23 views

Fluorescence spectrocopy, sensitivity

lets say we increased the excitation wavelength higher than it should be, what effect would this have on the sensitivity on our analysis, or changing the emission wavelength to a higher value than it ...
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2answers
25 views

Fluorescence Spectra, emission spectrum

What exactly does the excitation spectrum tell us about a sample in Florescence Spectroscopy, what information does it tell us? I know that we will get an output of concentration vs intensity but ...
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1answer
36 views

An issue with Bouger-Lambert Law

I'm certain that I misunderstand this law. It states that: $$I = I_o e^{-kb} $$ and after rearranging: $$ A = ln{I_o}-lnI $$ where $A$ stands for absorbance. 1) Does is mean that when the ...
4
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1answer
179 views

Why is filter paper fluorescent?

Typical filter paper used in chemistry lab (e.g. Whatman #1) exhibits autofluorescence in near UV with excitation maximum at 365 nm and emission maximum at 440 nm. It was reported in literature1 that ...
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49 views

Why is NH4OH used in Polarimetric analysis?

Why is a sugar solution pre-treated with ammonium hydroxide before analyzing? And why is it specifically ammonium hydroxide instead of sodium hydroxide or calcium hydroxide?
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1answer
112 views

How do I perform a gravimetric analysis of Portland cement?

To determine the silica ($\ce{SiO2}$) content in Portland cement by gravimetric analysis it is digested in $\ce{HCl}$ and the silica residue is eventually measured. The chief constituents are ...
5
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98 views

Standard solution and extracted solution : same concentration?

Summary : I am currently testing how a certain type of foam adsorbs HAP, PCB and OCP, and to this end I am depositing some on the foam, then extracting it. To know how much was extracted, I need to ...
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127 views

Why is absorbance spectrum continuous and not quantized?

1) In text books, the absorption event is usually described by a figure shown below1: light excites electrons to higher states in atom or molecule. The difference between the ground state and the ...
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159 views

Are refractive or density based Brix meters better for use with alcoholic drinks?

Assume that somebody wants to measure the sugar content of a liqueur. It seems that there are two types of Brix meters for it, ones which use the solution density and ones which use refraction of ...
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1answer
60 views

Can F2/HF be separated using acid/base solutions in series?

I am trying to verify the results of EPA method 26A (http://www.epa.gov/ttnemc01/promgate/m-26a.pdf). The Method claims to be able to separate and quantify a mixed halogen/halide gas stream. Although ...
3
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1answer
158 views

A COSY NMR problem. How to draw the spectra?

Does anyone know how to draw (predict) a hypothetical COSY NMR spectra for AMX spin system (the spin of A M X nuclei is 1/2)? Thank you very much!
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1answer
58 views

A student is provided with 500 mL of 600 ppm solutions of fructose. What volume of this solution in millilitres contains 0.15 fructose? [closed]

A student is provided with 500 mL of 600 ppm solutions of fructose. What volume of this solution in millilitres contains 0.15 fructose? Does this mean that I just have to use 600 ppm as the ...
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2answers
34 views

What are the limits of analytical chemistry?

As I understand it, the branch of chemistry dealing with identifying substances present in a sample is called "analytical chemistry". This branch looks vast and complicated, with lots and lots of ...
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24 views

What are the products formed by a typical wood fire? [duplicate]

What are the products formed by a typical wood fire? I tested the ash from my fireplace and found it to be on the acid side. While this question has been partially answered in answers to another ...
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1answer
332 views

What is pre-concentration (context: Breath analysis)?

What is the meaning of pre-concentration both in general and specific to this context of a) "In addition to consistent sampling protocols,.. pre-concentration, ...
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72 views

Quantifying Ascorbic Acid in Soft Drink

I have access to a GC/MS, FID, and a spectrophotometer. My first thought was to derivatize with trimethylsilylating agent, then run it by GC. Unfortunately the water is problematic. Heating it is ...
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50 views

How to test oxalic acid in potatoes

How could you test that there's oxalic acid in potatoes.For example, what chemical reacts to oxalic acid and then what will happen if it reacts?
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18 views

surface sensitive techniques

is there a way to analyze the surface of a transition metal (chemical composition and possibly oxidation states) immersed in a molten KOH environment, while the metal is also under electrochemical ...
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0answers
502 views

Concentration of diluted sample based on absorbance curve

I have a plot of Absorbance (ABS) vs concentration, and the fit curve is $$ Y = 0.1081 x + 0.015 \\ R^2=0.9925$$ Y is ABS and x is concentration. I need to dilute ($1/100$) my sample to measure ...
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2answers
170 views

Interpretation of the following mass spectrum

I'm given the above spectrum. $M^+ = 102$, probably $\ce{C_6H_14O}$ or $\ce{C_5H_10O_2}$. I'm thinking of ethyl propionate. (that picture also shows the fragments I expect). I can account for the ...
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2k views

How do I calculate the cell voltage using the following half-reactions and solubility products?

$$\ce{Cu_{(s)}|CuI_{(s)}|I^{–}_{(aq)}||Cl^{–}_{(aq)}| AgCl_{(s)}|Ag_{(s)}}$$ The concentrations of $\ce{NaCl}$ and $\ce{KI}$ are at $0.120 M$ and $0.090 M$, respectively, in the following ...
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1answer
67 views

How to interpret a MALDI mass spectrum?

I have some questions regarding how to read a MALDI mass spectrum in a paper. I am a biologist by training, so I would like some analytical chemists to help me out. The researchers ran a western ...
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87 views

which are the possible ways to detect impurity in drugs?

I want some information regarding the protocol for determining any type of impurity in pharmaceutical substances or drug product. Which type of impurities can be identified by HPLC and MS? what is the ...
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128 views

Yellow precipitate in the presence of ammonium molybdate?

We had analytical chemistry experiments to determine acidic radicals from a mixture of two salts. After the chloroform-chlorine water test for distinction between halides $(\ce{salt\ solution + H2SO4 ...
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1answer
142 views

Shelf-life of solutions

If I prepare the silver nitrate solution or any other solution, how can I know the shelf life of this solution? I know that it depends on the stability of the substance, but maybe there is some ...
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3answers
304 views

How do we actually know the chemical structure of a compound?

If a compound is placed before you and you are asked to determine what it is and what it's structure is,how do you actually do that ? This might be a baby question for most of you but I am not from ...
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116 views

Analytical solution to first-order rate laws

Does anyone know the analytical solutions to the following rate laws: 1) $\frac{d\rho_W}{dt} = -\rho_W*(K_1+K_2+K_3)$ 2) $\frac{d\rho_T}{dt} = \rho_W*K_2 - (K_4+K_5)*\rho_T$ 3) $\frac{d\rho_C}{dt} ...
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0answers
56 views

What is the effect of temperature during Cryotrapping?

I'm working on a lab report that has some specific questions that need to be included. The lab work itself dealt with GC-MS. What is the effect of the temperature selected during ...
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1answer
98 views

What is the best way to detect the presence of tear gas?

I realise that tear gas can be several different things (Pepper spray / CS Gas / CR gas, PAVA, etc) Is there a good way to detect some or any of these in the air? Ideally using an electronic sensor ...
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56 views

Testing for Iron-Gall Inks

I have to bottles of Lamy blue-black fountain pen ink. It turns out that some months ago the composition of the ink was changed by the manufacturer and there is no difference in the package. Before, ...
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1answer
130 views

Analysis of a mixture of carbonate salts

We've got a mixture of carbonate salts. It's a buffer, used in fish tanks. How might we go about identifying the components and their concentrations? I suspect it'd be hard to separate some of this. ...
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3answers
333 views

Why do you need a strong base for a titration

For a titration, if you want to know the concentration of an acid you use a strong base such as NaOH. My question is; why you can't use a weak base for this purpose? Is it because the calculation ...