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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0answers
68 views

Can an iron meteorite contain these chemical elements? [on hold]

I would like to know that maybe this matter.
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1answer
63 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 + $W_{\ce{SiO_2}}$...
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43 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 ...
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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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1answer
88 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 - $\ce{BaSO4 + 2 HCl ->BaCl2 + H2SO4}$
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29 views

Qualitative Analysis

What is the green solution that gives yellow precipitate when reacted with lead (II) nitrate and that gives a green precipate when reacted with aqueous sodium hydroxide ? I'm confused with this ...
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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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Would two different Plaster of Paris samples have different chemical signatures?

Weird question, but... would a spectroscopic analysis of a plaster of Paris sample reveal a chemical identifier that could be used to compare that sample against another. I want to be able to say ...
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2answers
151 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 ...
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How to relate the particle size and molecular weight of the same compound, calculated using particle size analyzer and Maldi, respectively?

In my analysis, the particle size of the compound is 48 nm, and molecular weight of the compound is 450-600 Daltons, using CHCA matrix. I need to relate these two datas. And am not sure about the ...
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1answer
53 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?
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1answer
22 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 ...
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3answers
145 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 ...
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0answers
25 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 ...
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1answer
216 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, ...
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1answer
139 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 ...
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2answers
68 views

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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86 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 ...
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1answer
40 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 ...
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173 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 ...
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71 views

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 ...
4
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1answer
258 views

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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1answer
77 views

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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1answer
172 views

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 ...
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1answer
1k views

Calculation of empirical formula from elemental analysis

A compound contains 40.0% Carbon, 6.7% Hydrogen, and 53.3% Nitrogen (by mass). Calculate the empirical formula. I'm getting $\ce{C7H14N8}$, but my professor says it is $\ce{CH2N}$. Which is the ...
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How to determine DDVP quality before appplication

The question is quite straightforward I need to determine the quality of 2,2-dichlorovinyl dimethyl phosphate (commonly abbreviated as DDVP) it is solved in xylene (50%). The purpose is to know if it ...
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1answer
171 views

metal oxide analysis

I am looking in to analytical techniques for a future project. I may have a mixture of metals, i.e. an alloy, which I am thinking XRF spectroscopy would be the best quantitative technique. I could ...
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1answer
1k views

How to test for magnesium and calcium oxide?

Is there a way to test for $\ce{MgO}$ and $\ce{CaO}$? I want to prove that $\ce{MgO}$ and $\ce{CaO}$ are created from their respective calcinations. $$\ce{MgCO3 (s)->[heat] MgO(s) + CO2(g)}$$ $$...
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2answers
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experimentally determine oxidation state of Iron compound

I need to make several Iron compounds but I am having a bit of trouble finding a decent way to determine the oxidation state of Iron. I'm starting with a Iron(II) compound that I try to oxidize using ...
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1answer
749 views

Why do rare earth metal oxides vary in color so much?

I only know a little about what causes different color, but I know it has to do with the electron orbitals and how they reflect or absorb/emit incoming light. The rare earth metals are in the ...
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2answers
1k views

How does a mercury detector work?

I am new to chemistry and saw a "portable mercury vapor monitor." How do these machines work?
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1answer
161 views

How to measure the amount of calcium in a supplement?

In chemistry lab, my group was assigned to determine the actual amount of calcium in a supplement. We did this successfully using HCl to dissolve the tablet, vacuum filtration, and then the addition ...
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1answer
129 views

Reagents used to prepare organic ICP standards, from scratch

I am trying to figure our how I can make my own calibration standards for organic ICP analysis. I assume that I need organometallic compounds to mix with base-oil/mineral-oil to prep the standards, ...
2
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1answer
547 views

Heating organic compound in a stream of nitrogen gas

This is related to estimation of percentage of oxygen in an organic compound and my textbook states: A definite mass of an organic compound is decomposed by heating in a stream of nitrogen gas. I ...
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1answer
820 views

Carius method for quantitative analysis of halogens

Carius method: A known mass of an organic compound is heated with fuming nitric acid in the presence of silver nitrate contained in a hard glass tube known as Carius tube, (Fig.12.17) in a furnace I ...
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2k views

Lassaigne's test for sulfur

The sodium fusion extract is acidified with acetic acid and lead acetate is added to it. A black precipitate of lead sulphide indicates the presence of sulphur. What is the need for acidification of ...
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1answer
1k views

Why is copper (II) oxide used in quantitative analysis of carbon?

What is the significance of using cupric oxide in the quantitative analysis of carbon? As far as I can tell from my research, only $\ce{CuO}$ is used to oxidize carbon to $\ce{CO2}$. Why can't we ...
2
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1answer
125 views

Determine the quantitative composition of a solid sample containing Co, Mn, Al, C, and O

I have a solid sample that contains Co, Mn, Al, C, and O. The sample mass is ~200 mg. I need to determine what the composition of this sample is. I've looked at atomic adsorption spectroscopy, but ...
3
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2answers
2k views

Method and Tips for Inorganic Qualitative Analysis

In a few weeks time, I will be doing an inorganic qualitative analysis test which is very pressed for time (a majority of people don't finish). The form of the test is most likely going to be that ...
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1answer
271 views

Detection of chloride anion

In a sample solution, containing $\ce{Cl-}$, while conducting the test for detection of $\ce{Cl-}$ ion first it is acidified with conc. $\ce{HNO3}$ then cooled and then $\ce{AgNO3}$ solution is added. ...
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1answer
102 views

Finding out the composition of seawater/brine?

As part of a project, I am working on precipitating salts from seawater and brine. I have a sample of seawater and I need to measure the concentrations of $\ce{Mg^2+, Ca^2+ and Li+}$ present in the ...
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626 views

How do I calculate the molecular mass of a complex in a complexometric titration with EDTA?

I had to titrate 0.35 mmol (3.2 g) of $\ce{Co2F2(Hdmpz)6(BF4)2}$ in a solution with 10 drops of 37 % $\ce{HCl}$, 10 mL of 4 M $\ce{NaOAc}$, 25 mL water and xylenol orange as indicator with a 0.05 M ...
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37 views

Is this problem doable with the information given?

Can I solve this problem without knowing any starting amounts? An element $\ce{X}$ forms iodide ($\ce{XI3}$) and chloride ($\ce{XCl3}$). The iodide is quantitatively converted to the chloride when it ...
5
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1answer
96 views

Can chemicals be identified by their molar mass?

Wouldn't it be possible to identify a chemical by measuring its molar mass? How much accuracy does the measured molar mass need to be to guess what chemical it could be? EDIT: @ortho makes an ...
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122 views

Qualitative Analysis for Chemistry Project

I am making a chemistry project wherein I wish to analyze the contents of purified and unpurified water, mainly the salts contained in them. What I wish to know is: What is the best way to do this? ...
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1answer
518 views

Representing woody biomass concentration for kinetic reactions

Woody biomass is composed of cellulose, hemicellulose, and lignin components. The following diagram provides representative formulas for each component: Biomass can be represented by it's density, ...
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1answer
15k views

Elements of paper

I learnt that everything is made up of atoms even paper! After that, I was thinking what are the elements that made paper? Is there any chemical symbol for paper in general?
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30k views

How to find the molecular formula for a hydrocarbon compound from known combustion products?

What is the molecular formula of a compound containing only carbon and hydrogen if combustion of $1.05~\mathrm{g}$ of the compound produces $3.30~\mathrm{g}~\ce{CO2}$ and $1.35~\mathrm{g}~\ce{H2O}$ ...