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Questions tagged [elemental-analysis]

The science of determining the elements a compound is made of or deriving the sum formula thereof. Can be applied both to practical and theoretical questions

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Cobalt Nitrate Test

As, $$\ce{ZnCl2 + Na2CO3 -> ZnCO3 + 2 NaCl}$$ $$\ce{ZnCO3 -> ZnO + CO2}$$ $$\ce{Co(NO3)2 -> CoO + 2NO2 +\frac{1}{2}O2}$$ Hence, $\ce{CoO + ZnO -> CoZnO2}$ here, $\ce{Zn_{1-x}Co_xO2}$ (...
Daksh's user avatar
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16 votes
3 answers
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How can I identify the material of this mystery gear?

I have this small gear which has sat on my desk for a couple years. I can't remember where it originally came from or what material it's made out of, so I'm hoping you can help me solve this mystery. ...
hifkanotiks's user avatar
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What is the most accurate way to determine the amount of water in a material from XRF and LOD-105 results?

this might seem like a silly question but I want to be sure. I have the results from an external laboratory for the bulk chemical composition (by XRF) and moisture (by Loss on Drying to 105 degrees ...
Hendrix13's user avatar
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5 votes
2 answers
861 views

False positive test for chloride ions during lab practical

In my highschool practical examination yesterday, I was given an inorganic salt to identify using chemical tests. The test I performed for the presence of chloride was to heat salt in a test tube with ...
Gaurav Sai Maddipati's user avatar
2 votes
0 answers
47 views

Negative absorption coefficient

What does a negative absorption coefficient mean? In detail - I participated in a Synchrotron virtual laboratory. I have to analyze the results and understand what a negative absorption coefficient ...
Roni Amit's user avatar
2 votes
3 answers
126 views

How to identify salts using mutual reactions

There are ten test tubes in the rack at your disposal (1 – 10) and each test tube contains one of the aqueous solutions of the following salts: $\ce{Na2SO4, AgNO3, KI, Ba(OH)2, NH4Cl, Ag2SO4, Pb(NO3)2,...
Harikrishnan M's user avatar
-1 votes
1 answer
62 views

Reactivity in my standard solution of Cu, P, Al, Ca, Fe, K, Mg, Mn, Na and S in 7,8% HNO3 and H2O2

I have a problem with my standard for ICP-OES. It contains the following elements Cu, P, Al, Ca, Fe, K, Mg, Mn, Na and S in a solution of 7,8% HNO3 and H2O2. I cannot make it work for reading P and ...
Mette's user avatar
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2 votes
1 answer
137 views

Equipment recommendation for atomic absorption spectroscopy (AAS) testing for mercury, lead, and cadmium

I work in a public health laboratory in a small mining town and we have the chance to buy equipment to test for lead and cadmium in wastewater, and mercury in not just wastewater, but also in blood, ...
JPertuz's user avatar
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2 votes
0 answers
72 views

Prepration of standards for analysis of chromium using AAS

I have conducted experiments to study specific adsorption of chromium in various soils and I made my all solutions of cr with using 0.01M NaNO3 as background electrolyte. (I made solutions of 5 ...
DILEEP SINGH's user avatar
3 votes
0 answers
186 views

What causes HPLC peaks to look like gauss curves?

I was wondering how the form and curvature of HPLC peaks come to be. As I understand it, the mobile phase which contains the analyte, runs through the column. Many times, the distribution equilibrium ...
Mäßige's user avatar
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3 votes
1 answer
272 views

Detection of Nitrogen and Sulfur in Lassaigne's Test

In Lassaigne's test for the detection of nitrogen and/or sulfur in organic compounds, we prepare Lassaigne's extract. In this extract, NaCN is formed if nitrogen is present, and $\ce{Na2S}$ is formed ...
R H's user avatar
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9 votes
2 answers
1k views

Why are sulfites often ignored in soil studies?

From a document on soil chemistry that I am reading: The acid-base potential of a soil takes soil pH, total sulfur (sulfides and sulfates), and neutralization potential into account to determine the ...
Al Lelopath's user avatar
1 vote
0 answers
85 views

What is the correct way to specify the weight fraction from bulk compositional data with a listed total % (e.g. from XRF, ICP)?

TL;DR = With bulk composition results, such as from X-Ray Fluorescence (XRF) testing, is the mass fraction of a given analyte that analyte given as a % or the analyte divided by the given total mass %?...
Hendrix13's user avatar
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battery using zinc, copper, and vinegar

I filed one side of a penny to reveal the zinc; then I bent the coin and dropped it into a cup of white vinegar. Shortly afterward, many tiny bubbles were forming on the zinc side. Later on, I noticed ...
Christian Fiore's user avatar
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64 views

Measuring Rare Earth Element Concentration in a Solution

I am interested in repeating the experiment as detailed in this paper: Study on Rare Earth Elements Leaching from Magnetic Coal Fly Ash by Citric Acid In the paper, coal fly ash is leached by citric ...
rubpy32's user avatar
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1 answer
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Cant figure out whether Lithium or Strontium is in my substance? [closed]

So for uni I got a substance and I have to basically figure out which anions and cations are in it. I get two chances to guess otherwise I get a new substance and have to start from scratch. Anyway ...
user125709's user avatar
-1 votes
1 answer
3k views

P2O5 concentration % based on a 75% Phosphoric Acid Solution [closed]

I have a very poor chemical background, so please be indulgent in the case my question seems silly. I need this clarification for a practical application: If I want to obtain a P2O5 concentration of 4,...
Nemesius's user avatar
-1 votes
2 answers
256 views

Why the electrode that is the electron source on a x-ray tube is called cathode? [closed]

In electrochemistry, the electrode that lose electrons and oxidizes is called anode. Why on an x-ray tube the electrode that lose electrons is called cathode?
Tito Morenno Pontes e Souza's user avatar
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60 views

Where can I find any assay of common baking soda (for example Arm and Hammer or generic grocery store brands)?

I am looking for any assay of common baking soda, listing approximate percentages of impurities or trace elements for example potassium, boron, chloride, fluoride, etc. For example my naive guess ...
Nissim Nanach's user avatar
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2 answers
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How much Na2O (from NaOH) do I add to sodium silicate with a weight ratio of SiO2/Na2O = 2.34 to get the solution to a weight ratio SiO2/Na2O = 1.9?

There is some confusion in industry as sodium silicate is made with NaOH but given a ratio with respect to Na2O (i.e. SiO2/Na2O not SiO2/NaOH). I presume it follows from this equation: 2NaOH -> ...
Hendrix13's user avatar
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2 votes
0 answers
48 views

Preparation of isotopic CO2 standards from Sn-encapsulated CaCO3

I wish to prepare isotopic CO2 gas standards for highly 13C enriched CO2. The CO2 concentrations will be ~1000 ppm, with the balance either N2 or zero air. My plan is as follows: Encapsulate labeled ...
user278411's user avatar
2 votes
0 answers
194 views

Which salts give the sodium carbonate bead test?

Apart from the borax and the phosphate bead tests, there's also this one. It's done by heating the white bead of sodium carbonate and the salt with potassium nitrate; green and yellow colours ...
harry's user avatar
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5 votes
1 answer
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Can we use silver nitrate to distinguish between chloride and carbonate salts?

Initially, we are given a solution containing two salts, they can be either carbonate or chloride salts (we do not know their composition initially). Generally, $\ce{AgNO3}$ is used as a confirmatory ...
Jay's user avatar
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-1 votes
1 answer
56 views

Whatman 41 filter uses for? [closed]

I was reading a research article related to winter fog, so the researcher collected aerosols on Whatman 41 filters every 12h, and we know that Whatman 41 filters are usually used for Qualitative ...
Autodidact's user avatar
3 votes
4 answers
3k views

Chemical elements or compounds with yellowish white color [closed]

Are there chemical elements or compounds that have a yellowish white (cream) color in their natural state?
Somanna's user avatar
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2 votes
1 answer
69 views

Free refined value in Rietveld

I have a question about Rietveld refinement The author of this paper claimed that the free refined CN ligand is 1.081. However, they does not show how they got that number. They stated it was based ...
Alvero's user avatar
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7 votes
1 answer
436 views

Determining stoichiometry in ICP-OES data analysis

I have questions regarding data analysis for an inductively coupled plasma (ICP) experiment from a paper by Wang et al. [1]. The generic formula for the chemical compound is $\ce{Na_{2−x}Fe[Fe(CN)6]}$...
Alvero's user avatar
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-2 votes
1 answer
113 views

A basic physical chemistry problem [closed]

I am a high school student and have just begin my classes(online). I just started physical chemistry but I know about moles, percentage composition, empirical formula. I haven't been able to solve ...
Arjun's user avatar
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1 vote
1 answer
189 views

Arsenic bound proteins confirmatory test

I want to confirm the presence of arsenic in some protein samples, apart from the marsh test can I use the following method?-- Arsenic is present as arsenic (III) ion in the samples. Hydrogen sulfide ...
pjmathematician's user avatar
1 vote
0 answers
225 views

Chemical Composition of NMC cathode in lithium ion battery

I am working with lithium ion batteries having the cathode material as NMC i.e. LiNixMnyCozO2, wherein x + y + z = 1. The proportion of Nickel, Manganese and Cobalt in the cathode varies, but mostly ...
Ved Soni's user avatar
-1 votes
1 answer
165 views

Is it safe to touch salts given to you for analysis? [closed]

In our chemistry practical paper (High school level), Inorganic salt analysis is one of the questions asked. We are given a petri dish with a sample of salt and are asked to find the cation and anion ...
Aniruddha Deb's user avatar
0 votes
1 answer
122 views

Is it possible to obtain the amount of air required for a combustion analysis?

I'm not very sure if the required amount of oxygen (I assume) can be found by only knowing the amounts of the produced subtances after a combustion. To illustrate this I found this problem: $1.14\,...
Chris Steinbeck Bell's user avatar
-1 votes
3 answers
991 views

Do the procedure used to find the empirical formula from combustion analysis be extended in other cases when is not specifically mentioned?

The situation is as follows: A sample of $\pu{19.40 g}$ from a certain compound consisting only in $\ce{K, Cr}$ and $\ce{O}$, receives a treatment. This gives $\pu{7.6 g}$ of $\ce{Cr2O3}$ and $\pu{...
Chris Steinbeck Bell's user avatar
-1 votes
1 answer
447 views

What does it mean to calculate "weight of SiO2 in the form of Si"?

This is with reference to the typical mass balance problems in iron making. Whenever we are asked to mole balance $\ce{SiO_2}$ it is treated this way: $W_{\ce{SiO_2}}$ from iron ore + $W_{\ce{SiO_2}}$...
Kedar Lodge's user avatar
0 votes
1 answer
96 views

SO3 in wood ash

I have seen several sources note that wood ash typically contains 3–4 % $\ce{SO3}$ by weight. My question is, why would ash have any $\ce{SO3}$? $\ce{SO3}$ boils at 45 °C, so it should have all boiled ...
R Dev's user avatar
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2 votes
0 answers
86 views

What instrument is used to detect heavy metals? [closed]

If i have blood sample, organ tissue sample or food sample, what analytic technique is used in laboratory to detect the ppm levels of heavy metals? What electronic intrument they use?
wav scientist's user avatar
13 votes
3 answers
1k views

How is hair tissue mineral analysis performed?

This might be a mixed chemistry / physics question, but I've always wondered what methods were used to precisely determine the levels down to trace amounts of all minerals in human tissues. I know ...
Veritas's user avatar
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0 votes
1 answer
951 views

Is barium sulfate soluble in dilute mineral acid?

I have read that $\ce{BaSO4}$ is soluble in $\ce{HCl}$ , but I am not sure whether this works for dilute acid as well. The reaction is - $\ce{BaSO4 + 2 HCl ->BaCl2 + H2SO4}$
Yudi's user avatar
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7 votes
2 answers
176 views

Removing sodium borate for the test proving thiocyanate ions

I've just learned that when carrying out the identification test for thiocyanate ions borax can induce a false positive and therefore needs to be removed. I couldn't find the answer on google so I'm ...
bobsburger's user avatar
0 votes
2 answers
3k views

Sodium Sulfate vs Sodium Sulfite

I recently took a test and one of the questions was: Which procedures will allow a student to differentiate between solid sodium sulfate and solid sodium sulfite? I. Make solutions of each ...
Cyclopropane's user avatar
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0 votes
1 answer
1k views

How can I Identify Elements in Objects? [closed]

Since all objects on earth are composed of elements, how can I identify the fundamental make-up of objects such as trees, glass, bricks, wood, plastic, shoes, and other entitys?
Isaac's user avatar
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2 votes
1 answer
49 views

Taking a procedure for ICP and adapting it to use with AAS

I was reading a paper regarding metal detection and they gave their procedure for an acid digest of a soil sample which was then analysed by ICP-OES. They used nitric acid, hydrogen peroxide and ...
Wednesday Fades's user avatar
1 vote
3 answers
180 views

Combustion analysis methodology question

I am questioning the answer key of an exam question my chemistry professor has given, because I think there is a flaw in the methodology of the exam answer. I have worked out my solution using my ...
Liam White McShane's user avatar
1 vote
0 answers
38 views

What happens to chromium (as Cr2O7-) in the plasma of the ICP?

I have recently been analyzing some biological samples for chromium using a standard Cr(VI) solution for external calibration. Cr standards are typically supplied in a 2% nitric acid matrix. That ...
Waif's user avatar
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2 votes
1 answer
1k views

Dissolving cast iron in nitric acid

Decades ago my job was to find the silicon content in cast iron gravimetrically. The first step was dissolving the sample in hot Nitric acid. Did this turn all of the constituents in the sample, ...
Bob's user avatar
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3 votes
1 answer
394 views

Organic molecules with 21.62% oxygen

I have been told to answer the following question: Seven different compounds, all either alcohols or ethers, contained 21.62% oxygen. Find the structural formula for all of these compounds and ...
Maxim Vaughan's user avatar
3 votes
2 answers
227 views

Does ICP-OES detect molecules in suspension?

I'm curious whether ICP-OES has the ability to detect molecules in suspension?
Tunk's user avatar
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3 votes
0 answers
474 views

Why aren't lasers used as light sources for atomic absorption spectroscopy?

Atomic absorption spectroscopy yields extremely narrow signals. It is difficult to separate white light with sufficient precision using monochromators, and hollow cathode lamps are often used as light ...
Martin's user avatar
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-1 votes
1 answer
65 views

Lactic acid - Elementary analysis

Lactic acid is a hydroxy carboxylic acid that can form in the muscles and lead to soreness. The molecular weight of the lactic acid is $\ce{90.1 g/mol}$. Elemental analysis shows that the substance ...
F.Sal's user avatar
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1 vote
0 answers
472 views

Determining the chemical formula of a polyiodide Salt

I've got a compound with formula $\ce{N(CH3)4.I(I2)_x}$. By mass I've got $\pu{0.138 g}$ of $\ce{I2}$ present out of $\pu{0.189 g}$ of polyiodide added. How do I find $x$? This is the exact part of ...
Pandafish's user avatar