All Questions
Tagged with inorganic-chemistry analytical-chemistry
139
questions
16
votes
3
answers
2k
views
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.
...
- 319
2
votes
1
answer
120
views
The formula of ammonium phosphomolybdate
It is written in my qualitative chemistry textbook that phosphate could be tested by introducing phosphate, nitric acid and ammonium molybdate which gives (NH4)3H4[P(Mo2O7)6].
I found out in the ...
user139387
0
votes
1
answer
161
views
Would ferrous ion give the flame test?
My question to ask is "Does $\ce{Fe^2+}$ ion give flame test?"
Background: Last month, I gave the JEE exam and a question was as follow:
Number of metal ions characterized by flame test ...
3
votes
1
answer
179
views
Role of MnSO4 in permanganometric titration
This might sound like a stupid question, but I have been unable to wrap my head around it.
Recently in a lab I had to titrate H2C2O4 with KMnO4 in acidic medium (H2SO4). However, in the work, it ...
3
votes
1
answer
192
views
Why is there a yellow solution formed upon reaction of silicon tetrachloride with water?
I've read somewhere that reacting the two will give a white solid and a yellow solution. I'm assuming the white solid is the silicon dioxide, but what is the chemical origins of the yellow colour of ...
- 49
1
vote
0
answers
146
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Are there TLC stains for organo fluor compounds or anorg. fluoride that are useful for selecting the product containing fractions post purification
Are there TLC stains that work with fluoride or with organofluor compounds? I have a fluorinated phosphonic acid that does not stain with conventional means. I did research in many of the known and ...
- 799
5
votes
1
answer
112
views
Why are fluorine-19 NMR spectra less affected by paramagnetic centers than other common nuclei?
I know that 19F NMR spectra are less sensitive to paramagnetic centers as an empirical fact: it’s my experience and that’s what people in my lab have always been saying.
For instance, some of my ...
- 51
1
vote
0
answers
90
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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 %?...
- 500
-1
votes
1
answer
332
views
Calculate volume of hydrogen gas evolved
MCQ Question:
Ammonia borane in water can release hydrogen upon hydrolysis while forming NH4BO2 as the other
product.
The volume (cm3) of hydrogen gas which will be evolved from the hydrolysis of 309 ...
- 127
2
votes
1
answer
1k
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How do different x-ray tube emission profiles (i.e copper vs cobalt sources) affect XRD samples containing iron (results included)?
Background:
I'm a student and have recently done some XRD on some iron ore mine tailings which came from an Australian mine tailings storage dam. The redness in colour and industry source led me to ...
- 500
2
votes
1
answer
55
views
Why and how are mullites (and in extension solid solutions) formed and how are their formulas conceived as opposed to regular crystalline solids?
From doing more Phase ID for XRD on aluminosilicate based coal fly ash samples, I've seen mullite phases appear a few times which have the non-stoichiometric chemical formula $Al_{4+2_x}Si_{2-2x}O_{10-...
- 500
1
vote
2
answers
545
views
In qualitative analysis for basic radicals, why are group 2 cations not precipitated along with group 4?
To ensure that group 4 cations are not precipitated with group 2, we add dil. $\ce{HCl}$ to ensure only group 2 sulfides of lower $K_\mathrm{sp}$ are precipitated.
For group 4, we add $\ce{NH4OH}$ ...
- 19
1
vote
3
answers
661
views
How is 1 mole hypochlorite ion equivalent to 1 mole chlorine gas?
According to my book, 1 mole ClO- is equivalent to 1 mole Cl2. How is that even possible? 1 mole ClO- contains 1 mole Cl atoms. On the contrary, 1 mole Cl2 gas contains 2 mole Cl atoms. So, how are ...
- 201
0
votes
1
answer
139
views
Should I write formula for oxalate or oxalic acid while balancing a redox reaction using the ion-electron method?
Problem:
Balance the following reaction using the ion-electron method:
$$\ce{H2C2O4 + KMnO4 + H2SO4 -> CO2 + MnSO4 + K2SO4 + H2O}$$
My book's solution:
Oxidation half-reaction:
$$\ce{C2O4^2- -> ...
- 201
0
votes
1
answer
101
views
Why did my book write S2- if hydrogen sulfide isn't ionic?
Problem:
Balance the following reaction using the ion-electron method:
$$\ce{KMnO4 + H2SO4 + H2S -> MnSO4 + S + K2SO4 +H2O}$$
My book's solution:
Oxidation half-reaction:
$$\ce{S^{2-}->S + 2e^{-}...
- 201