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

learn more… | top users | synonyms

2
votes
1answer
37 views

Precautions and tips for Qualitative Inorganic Analysis of Coins

I'm a highschool student and as part of an investigatory project, I have decided to analyse which metals are present in our everyday coins. I chose this because in my previous academic year, I had ...
2
votes
1answer
36 views

What do chemical constituent measurement units 'g%g' and 'µg g⁻¹' mean?

I'm trying to understand the following data being presented in this paper measuring the mineral content of the Cannabis sativa plant (leaves and inflorescences): I need to interpret these data ...
4
votes
1answer
75 views

Why is XeF2 linear? IR related question

The vibrational modes of $\ce{XeF2}$ are at 555, 515, and 213 cm-1 but only two are IR active. Explain why this is consistent with $\ce{XeF2}$ having a linear structure. From what I know, since it ...
1
vote
1answer
21 views

How to calculate the detection limit?

I am having trouble figuring out how to calculate the detection limit. Here is the question: You and your friend working in a different lab have been given an unknown water sample that contains ...
3
votes
1answer
51 views

how to measure dissolved oxygen?

How do you measure dissolved oxygen reliably in a culture of cells? This page has info on one sensor: http://water.me.vccs.edu/concepts/domeasure.html how would you know that this sensor is working - ...
0
votes
2answers
93 views

How do I determine the mass percent of Barium nitrate and Sodium acetate in an original unknown solution

I am given $20 \mathrm {mL}$ of the unknown mixture of Barium Nitrate and Sodium Acetate dissolved in water. I am given the total mass of the two solids before they were put into the mixture. I am ...
0
votes
1answer
30 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 $\ce{KCl}$ ...
2
votes
0answers
26 views

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: ...
2
votes
0answers
19 views

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

What kind of salts may I add in my GPC Eluent?
3
votes
2answers
107 views

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, ...
3
votes
3answers
56 views

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 ...
2
votes
0answers
54 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 ...
1
vote
1answer
38 views

Fluoride Color Reaction

I am trying to find visual ways to demonstrate water contaminants. For example, chlorine reacts to N,N-diethyl-p-phenyldiamine (DPD), forming a magenta color. The chemical doesn't need to be accurate, ...
2
votes
1answer
39 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 ...
1
vote
1answer
23 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 ...
0
votes
2answers
61 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 $\ce{NaHCO3}$ ...
0
votes
1answer
42 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?
6
votes
1answer
307 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 ...
3
votes
2answers
49 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 ...
2
votes
0answers
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 ...
4
votes
1answer
53 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 ...
2
votes
1answer
92 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 ...
0
votes
1answer
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 ...
0
votes
1answer
14 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 ...
2
votes
1answer
88 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 !
3
votes
1answer
45 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?
0
votes
0answers
27 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
votes
1answer
270 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.
3
votes
3answers
211 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 !
1
vote
1answer
144 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 ...
2
votes
1answer
88 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 ...
0
votes
1answer
169 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 ...
6
votes
2answers
86 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 ...
2
votes
1answer
67 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 ...
0
votes
0answers
89 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 ...
1
vote
3answers
84 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 ...
3
votes
1answer
38 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 ...
0
votes
2answers
59 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) ?
0
votes
1answer
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 ...
0
votes
0answers
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 ...
1
vote
2answers
30 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 ...
0
votes
1answer
37 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 ...
5
votes
1answer
198 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 ...
2
votes
1answer
567 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 ...
1
vote
2answers
64 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?
4
votes
1answer
127 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
votes
1answer
107 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 ...
3
votes
2answers
151 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 ...
2
votes
2answers
264 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 ...
2
votes
1answer
78 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 ...