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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why is the precipitate of carbonyl DNPH test red in colour? what is the main cause of the colour red? [duplicate]
2,4 DNPH test in qualitative organic analysis of carbonyl compound gives red ppt. what would have been the cause of that colour?
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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 ...
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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, ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 %?...
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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 ...
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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 ...
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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 ...
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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,...
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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?
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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 ...
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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 -> ...
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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 ...
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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 ...
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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 ...
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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 ...
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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?
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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 ...
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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 $\ce{Na_{2−x}Fe[Fe(CN)6]}$...
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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 ...
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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 ...
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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 ...
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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 ...
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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\,...
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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{...
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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 + $W_{\ce{SiO_2}}$...
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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 ...
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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?
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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 ...
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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 -
$\ce{BaSO4 + 2 HCl ->BaCl2 + H2SO4}$
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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 ...
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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 ...
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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?
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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 ...
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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 ...
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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 ...
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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, ...
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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 ...
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Does ICP-OES detect molecules in suspension?
I'm curious whether ICP-OES has the ability to detect molecules in suspension?
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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 ...
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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 ...
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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 ...
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How does the electron configuration correlate with the emission spectrum of an ionic compound? [closed]
trying to find a way to correlate the electron configuration of an ionic compound (ie. Cupric sulfate, potassium chloride, Cupric chloride, sodium carbonate, strontium chloride) with its emission ...
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In TOF Mass Spectrometry how does the detector 'know' the difference between ions of different elements?
After the positive ions have been accelerated, I know that they travel through the drift zone at different speeds due to their masses.
But surely, a heavier ion/element that enters the drift zone ...
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Quantitative elemental analysis in mixtures with internal standard normalization
I am trying to make a quantitative model for Laser Induced Breakdown Spectroscopy (LIBS) analyzing metal alloy samples. I am using an internal standard normalization (so far it produced the best ...
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XPS analysis intrepretation
A lab presented me with an elemental composition (mainly metals in char) derived from an XPS analyzer and mentioned that binding energies suggested a list of compounds (various oxides, sulfides and ...
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Oxide and chloride of a metal [closed]
I found this problem:
The oxide of a metal contains 60.0% metal and the chloride of the same metal contains 25.26% metal (in mass percents). What are the possible formulas for the oxide and the ...
