All Questions
12
questions
-3
votes
1
answer
91
views
Determining iron(III) content in mixture of iron(II) and iron(III) [closed]
Problem
Outline a plan of an experiment to determine the percentage of iron present as iron(III) in a solution containing $\ce{Fe^3+(aq)}$ and $\ce{Fe^2+(aq)}$ ions. You are provided with zinc, a ...
- 15
2
votes
0
answers
124
views
Is there a reason why we add (CH3CSNH2) but not H2S in qualitative group analysis? [closed]
Brief question: In $\ce{Cu}$-$\ce{As}$ group analysis we are expected to add thinoacetamide to make a precipitate with sulfide. Can we use $\ce{H2S}$ instead?
- 103
2
votes
1
answer
105
views
Can o-phenanthroline be used as a complexing agent for lead(II)?
I’ve been trying to find a method to perform a spectrophotometric analysis to determine lead concentration (on the ppm level). This would require some chelator capable of forming a coloured complex ...
- 467
4
votes
3
answers
947
views
Chemicals that form coloured complexes with Pb(II) cations
I’m currently conducting a photo-spectrometric analysis of lead concentration in water, and was looking into using Eriochrome Black T (EBT) as an indicator for $\ce{Pb^2+}$ (due to the complex forming ...
- 467
-1
votes
1
answer
43
views
What causes the differences in price in home testing kits for lead in water? [closed]
The price differences between home testing kits to test tap-water for lead are huge.
20 dollar will either buy 1 test kit or 100 test strips. Both are intended to test drinking-water safety.
What ...
- 249
5
votes
1
answer
2k
views
Calcium ion and sulfate did not form precipitate
I was in the chemistry lab earlier this week. We were doing a qualitative experiment (no concentration given for any solution).
I added an unknown solution that contains $\ce{Ba^2+},$ $\ce{Ca^2+},$ ...
- 205
0
votes
1
answer
161
views
Redox titration or iron(II)
The concentration of $\ce{Fe^2+(aq)}$ can be determined by a redox titration using
A. $\ce{KBr}$
B. $\ce{SnCl2}$
C. $\ce{KMnO4}$ (basic)
D. $\ce{KBrO3}$ (acidic)
Can anyone please help me on this ...
- 11
1
vote
0
answers
209
views
Qualitative analysis of iron(III) salt
Why will $\ce{Fe^3+}$ give brown ring test?
In my textbook it was given that ferric ion gives brown ring too. I am confused, if ferric ion is already present, then what will reduce nitrate ion to ...
- 313
1
vote
0
answers
102
views
What causes the turbidity when preparing Fenton's reagent?
New guy, please be gentle. I might ask questions not according to conventions, I am not a chemist nor do I study chemistry. Feel free to adapt the question and the tagging.
I am preparing a solution ...
- 173
1
vote
0
answers
37
views
Potentiometric determination of fluoride
We did an experiment of potentiometric determination of fluoride ions. In several beakers we added several concentrations of NaF solutions and then we added water. We calculated with the electrode the ...
- 477
9
votes
2
answers
1k
views
Why does Devarda's alloy include copper?
Devarda's alloy is used in the detection of nitrates. However, judging by the reaction equation, only aluminium plays the role of reducer:
$$\ce{3NaNO3 + 8Al + 5NaOH + 18H2O -> 8Na[Al(OH)4] + 3NH3(...
- 3,276
7
votes
1
answer
11k
views
Why does phosphoric acid mask the colour of iron(III) complex in water?
In the redox titration of iron(III) with permanganate or dichromate, we use phosphoric(V) acid to "mask" the color of iron(III) because it interferes with the end point color change.
What's the ...
- 115