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

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Purifying washing soda

I bought a box of A&H Washing Soda, the packaging of which implied that it was pure washing soda (sodium carbonate). On dissolving it in osmotically-purified water, however, I found that the ...
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35 views

How to report pH values?

I have measured the pH in the water-soluble fraction of a powder. I weighed in a certain amount of powder and a certain amount of water, and extracted the water-soluble fraction. I then measured the ...
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45 views

How to calculate the oxidation state and the number of equivalents oxidized with YBa₂Cu₃O₇

I've hit some trouble with these calculations and need help sorting out confusion. In the lab we synthesized $\ce{YBa2Cu3O7}$, per the lab manual $\ce{Y, Ba, O}$ have the usual charges of +3, +2, and ...
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26 views

Why do electrons not get paired up in [Fe(H2O)5NO]2+?

The magnetic moment of [Fe(H2O)5NO]2+ is 3.87 Bohr magneton, which implies there are 3 unpaired electrons. Since iron is in +1 oxidation state (due to charge transfer with nitrosyl group), it's ...
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22 views

Is it possible to separate out (MgxCu1-x)2(CO3)(OH)2 into simply (MgxCu1-x)(CO3)?

Good afternoon, Here is the problem I am stuck with, in particular just the first part of it. I have calculated the moles (4.492 x 10-3 mol) and I am quizzed with regards to the equation that occurs. ...
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29 views

Calibration Curve Error Propagation

I am using ED-XRF for geochemical analysis for a geology dissertation. The ED-XRF provides a ppm reading for elements and a 2sigma error, for example 472 +- 5.11ppm Sr. An example calibration ...
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17 views

The Workings of Pulse-Height Discrimination

Pulse-height discrimination is a common technique to filter out unwanted background signals from the analytical signals. But how exactly does it work? The analytical signals are not continuously ...
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53 views

Analytical Chemistry predicting the order of elution of compounds in a reverse phase HPLC

Predict the order of elution for a mixture containing caffeine and benzoic acid, using a reverse phase HPLC. Explain your answer. My try Since benzoic acid is more acidic that caffeine, which means ...
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114 views

Questions on reactions during salt analysis [closed]

I have two questions: What is the reaction between Diphenylamine with Nitrite compound during Nitrite test during anion analysis DIPHENYLAMINE - $\ce{(C_6H_5)_2NH}$ NITRITE - $\ce{NO_2^-}$ What is ...
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374 views

Would there be a difference if deuterium is embedded instead of protium (regular hydrogen) in acids?

So instead of regular hydrogen, it would be a deuterium (still a Hydrogen). For example, instead of $\ce{HCl}$ it would be $\ce{DCl}$ where D is a deuterium.
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65 views

What kind of compound absorption the 365nm UV light on TLC [closed]

What kind of compound absorption the 365nm UV light? compounds that has benzene ring or conjugated pi bond, make a fluorescence on 254 nm UV on TLC. what kind of moiety(functional group) make ...
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68 views

what is the white fuzz left behind on basement floor after puddle evaporated

My basement is quite dry (knock on wood!). Recently I brought into the basement for the winter a table from outside. The table had some ice stuck to it which I couldn't remove, so I simply let it ...
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40 views

Mathematical Statistics and Chemistry

I'm currently working towards a major in both chemistry and mathematical statistics as a part of my science degree, and I got to wondering: How will these two go hand in hand and help each other? ...
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70 views

When will the mass of the reactant increase while being heated up?

There is some kind of system which measures the mass of an unknown solid substance as it heats up, of course for the elemental analysis of the very substance. (didn't really find a good name for that ...
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31 views

Echelle Monochromators

"For any given order, the wavelength dispersion is approximately linear. but the dispersion is relatively small at lower orders or higher wavelengths." As you can see, wavelength dispersion and ...
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46 views

How does light get refracted through five lenses in a component of a spectrometer? [closed]

Question three in my Pre-lab questions for my Physical Chemistry practical is causing me problems. If a parallel beam of light hits the first lens with focal length 2F it will cause the light to ...
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22 views

Cation exchange capacity via IR spectroscopy? Is it as good as barium exchange? What is the intutition on how it works?

Cation exchange capacity is often regarded as the single best summary statistic for soil fertility. Years ago, I learned how to measure it myself, in a soil lab. I used compulsive barium exchange, ...
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65 views

UV-Vis Spectra: Multiple peaks for one component

I am working on a project in my lab, and we are analyzing capsaicin using HPLC. I am trying to find an appropriate wavelength for the HPLC using a UV-Vis spectrometer. When analyzing the pure ...
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149 views

Buffer Solution - Sodium Benzoate

A buffer with a pH of $\mathrm{4.79}$ contains $\mathrm{ 0.39\ M}$ of sodium benzoate and $\mathrm{0.10\ M}$ of benzoic acid. What is the concentration of $\mathrm{[\ce{H} ]}$ in the solution after ...
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21 views

Preparing standards for ion chromatography by weighing in amounts: correct for density?

Let's say we want to extract the water solvable part of an unknown powder, and analyse for anions. We put the powder in a tube with a filter at the bottom, add 10 mL water, and let the water run ...
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23 views

How report metal amounts as amount of their respective metal oxides?

I have performed an element analysis, and I I have calculated the amount of each metal in my sample, given in milligrams. Let's say I weighed in 10 mg of the powder. I want to see how much of that I ...
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451 views

Definition of major, minor, and trace elements in analytical chemistry

What is the definition of major, minor, and trace elements in a sample? I am unable to find this anywhere on the internet. Is it something like: Major elements are those > 0.1 % Minor elements are ...
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35 views

ICP-OES data treatment: correct for dilution and inweight, the units

Let's say the ICP-OES software gives me a concentration of 186,49 ppm (mg/L) of Mn. I diluted the acid digested sample to 14.2 mL. I weighed in 10.17 mg of the powder I analyzed. I need to calculate ...
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313 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 ...
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58 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 ...
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242 views

How can I deduce the linearity of XeF2 from the IR spectrum?

The vibrational modes of $\ce{XeF2}$ are at $555$, $515$, and $213~\mathrm{cm^{-1}}$ but only two are IR active. Explain why this is consistent with $\ce{XeF2}$ having a linear structure. From what ...
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90 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 ...
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87 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 - ...
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181 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 ...
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39 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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89 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: ...
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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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219 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, ...
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119 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 ...
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111 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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44 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, ...
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41 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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27 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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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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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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383 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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81 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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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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275 views

How can I determine the chemical composition of local rocks and minerals?

Specifically I live in the U.S. so I'm asking about an ordinary rock that you might find in your backyard or near a playground. Humans have discovered gun powder, petroleum, silica, iron, and many ...
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90 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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237 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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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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21 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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134 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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95 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?