Stack Exchange Network

Stack Exchange network consists of 175 Q&A communities including Stack Overflow, the largest, most trusted online community for developers to learn, share their knowledge, and build their careers.

Visit Stack Exchange

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

0
votes
2answers
23 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 ...
0
votes
0answers
5 views

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 ...
0
votes
1answer
38 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?
0
votes
1answer
14 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 ...
1
vote
3answers
138 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 ...
1
vote
0answers
23 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 ...
3
votes
1answer
148 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, ...
3
votes
1answer
103 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 ...
4
votes
2answers
53 views

Does ICP-OES detect molecules in suspension?

I'm curious whether ICP-OES has the ability to detect molecules in suspension?
3
votes
0answers
57 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 ...
-1
votes
1answer
34 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 ...
1
vote
0answers
125 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 ...
1
vote
0answers
69 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
votes
1answer
236 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 ...
3
votes
0answers
61 views

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 ...
1
vote
1answer
65 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 ...
1
vote
1answer
108 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 ...
3
votes
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 ...
0
votes
0answers
14 views

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 ...
1
vote
1answer
143 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 ...
-6
votes
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. $$\ce{MgCO3 (s)->[heat] MgO(s) + CO2(g)}$$ $$...
2
votes
2answers
2k views

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 ...
12
votes
1answer
625 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 ...
9
votes
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?
3
votes
1answer
148 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 ...
2
votes
1answer
122 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
votes
1answer
431 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 ...
4
votes
1answer
684 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 ...
3
votes
0answers
1k 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 ...
5
votes
1answer
823 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
votes
1answer
118 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
votes
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 ...
1
vote
1answer
228 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. ...
1
vote
1answer
95 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 ...
1
vote
0answers
585 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 ...
0
votes
0answers
36 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
votes
1answer
95 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 ...
1
vote
0answers
113 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? ...
6
votes
1answer
469 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, ...
1
vote
1answer
13k 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?
8
votes
1answer
28k 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 $1.35~\mathrm{g}~\ce{H2O}$ ...
4
votes
1answer
170 views

How to determine the molecular formula based on molecular weight, amount of substance, and partial masses of some, but not all contained elements?

I am working on a chemistry assignment and can’t figure out part of the problem. $0.2\,\mathrm{mol}$ of a compound with a molecular weight of $82$ contain $9.6\,\mathrm{g}$ of carbon, $1.2\,\mathrm{g}...
1
vote
4answers
675 views

Does a grain of salt have exactly equal amount of sodium and chlorine?

Does a grain of salt have exactly equal amount of sodium and chlorine? I know that the formula unit of salt is 1:1, but for example if there is 10000000 atoms of sodium is it possible that that there ...
2
votes
1answer
2k views

index of hydrogen deficiency

I don't really get the concept of index of hydrogen deficiency (IHD). Can someone please use an example to explain what $\mathrm{H_{reference}}$ and $\mathrm{H_{molecule}}$ are? I know the formula: $$...
2
votes
1answer
13k views

Detection of potassium ions

I've bought a white powder. The label on the package states that the powder contains sodium chloride, potassium chloride and potassium citrate. How can I make sure that the powder does indeed contain ...