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

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Gravimetric Analysis of phosphate while precipitating magneisum ammonium [on hold]

When precipitating magnesium ammonium phosphate in the gravimetric analysis of phosphate, you assume that the percentage of phosphorus in your 2-g sample is about 10%. How many milliliters of ammonia ...
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Filtration of chloride in gravimetric analysis

The final filtration of a chloride gravimetric analysis allows some very fine precipitate through the filter into the filtrate. Allowing the precipitate to stand longer (to "digest") may have reduced ...
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28 views

How to find the percentage contribution of a compound via gravimetric analysis?

You have a sample of silver alloy and would like to know how much silver is in it. Dissolve the silver sample in nitric acid. Filter to remove any insoluble material. Add an excess of $\ce{KCl}$ ...
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X-Ray Diffraction: Phase Identification Strategy

I am having some trouble with qualitative phase identification using x-ray diffraction (XRD). Here follows some basic information about the experiment: Instrument: ...
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18 views

What kind of salts may I add in my GPC Eluent?

What kind of salts may I add in my GPC Eluent?
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Absolute and relative uncertainty problems

My professor, for whatever reason, assigned problems for us to do without previously teaching us how to perform the problems which were given. If anyone happens to know how to do this and can show me, ...
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What is the procedure to create stock solutions?

Until now to execute this recipe, each time i had to count those milligrams/Liter. An enough difficult procedure. I am posting here this question to help me understand the procedure of creating ...
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46 views

Chemical structure of water-soluble polysaccharide

I don't know much about analytical chemistry, but I need to determine the chemical structure of a water soluble polysaccharide which is not pure and may have D-glucose, mannose and fructose. How do I ...
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37 views

How does lye appear in ashes?

One of the oldest recipes to create lye is this one: Take well burnt ashes and put them in a barrel Fill the rest of the barrel with water Leave the suspension for a week or two You can now try the ...
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20 views

Home-made way to detect lye in solution

I believe that electrolysis of salt water creates lye ($\ce{NaOH}$ - sodium hydroxide). In salt water, there's $\ce{Na+}$, $\ce{Cl-}$, $\ce{H+}$ and $\ce{OH-}$ as of ionts. So at cathode, you get ...
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50 views

Preparation of NaOH Solution

How would one prepare a one molar sodium hydroxide solution? I see a few issues with this: $\ce{NaOH}$ absorbs carbon dioxide. So old NaOH samples might have a significant portion of $\ce{NaHCO3}$ ...
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38 views

Analyzying Collection from Evaporation [closed]

A solution is 5.00% potassium chloride by mass. How much potassium chloride would you expect to collect by evaporating 150.0 g of the solution?
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275 views

Does knowing the ratio of masses of the elements in a compound lead to the unique chemical identity of the compound?

I was posed this question from a friend, however I am not necessarily sure. I think: yes, because a molecule of any compound is composed of a whole-number ratio of atoms of its elements, per the law ...
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44 views

Detection of magnesium in a buffer?

I have a PolyA tailing kit for putting PolyA tails on the 3' end of RNA. The kit comes with a proprietary 5X buffer and a 25mM MnCl2 solution, and in the standard set up I use 20uL of 5X buffer and ...
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19 views

What sort of lab can determine PAH concentration in a soil or charcoal sample? How difficult is it to do?

Non-chemist here. I'm curious how difficult it is to determine concentration of PAH in a sample of soil or powdered charcoal, or a sample of the two mixed together. What would be involved in doing ...
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49 views

How can I reverse engineer a commercial cleaning solution's “other ingredients”?

I have a commercial lens cleaning solution. The manufacturer of the solution claims it is not only distilled water and that the formula is confidential. I suspected it was only or mostly distilled ...
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1answer
65 views

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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22 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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13 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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83 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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36 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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26 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 ...
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124 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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99 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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92 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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84 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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104 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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81 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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36 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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55 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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79 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 ...
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34 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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56 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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28 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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29 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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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 ...
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193 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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309 views

Using Activities and extended Debye-Huckel equation, find the ph of the solution 0.020 M NaCl

This is from a study guide for an exam coming up. So the Question is: Use activities to calculate the pH of each of the following solutions, being sure to use $\alpha$ values and the extended ...
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53 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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120 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 ...
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102 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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134 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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213 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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70 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 ...
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169 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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63 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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37 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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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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503 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, ...