All Questions
Tagged with aqueous-solution analytical-chemistry
50
questions
2
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0
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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
974
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Creating a 10 ppb Lead Nitrate Solution
I’m trying to make a 10 ppb Lead Nitrate solution as part of a concentration calibration step for a Beer Lambert’s Law experiment. I plan on performing a dilution in three steps. The calculations have ...
- 467
1
vote
1
answer
372
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Creating 1L of 1000 ppb stock solution of Pb2+
I’m testing on samples that require a concentration of 1000 ppb (or 1 mg/L) of Pb 2+. My first thought was to simply dissolve 1 mg of Lead nitrate in 1 L of deionized distilled water to create 1 L of ...
- 467
2
votes
1
answer
105
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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
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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
0
votes
3
answers
231
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Is it possible to measure light absorbance for analysis of lead concentration without photospectrophotmeter
I’m designing an experiment which requires I measure final and initial lead concentrations for the determination of aqueous lead uptake by different mediums. Because lead concentrations would be ...
- 467
2
votes
1
answer
123
views
How concentrated does the analyte solution need to be in order to perform a (chelatometric) titration
I’m currently investigating a method to chemically pretreat cellulosic waste as bisorbents for enhanced uptake of lead in water. I intend to measure the initial and final concentration of water to ...
- 467
-1
votes
1
answer
43
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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
440
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Is chromate a suitable indicator for the titration of Ag⁺ with Cl⁻?
To titrate $\ce{Cl-}$ with $\ce{Ag+}$ we use chromate $\ce{CrO4^2-}$ as an indicator.
The titration reaction is:
$$\ce{Ag+ + Cl- <=> AgCl}\tag{R1}$$
$$K_1 = \frac{1}{K_\mathrm{sp}(\ce{AgCl})} =...
- 187
5
votes
1
answer
2k
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Calcium ion and sulfate did not form precipitate
I was in the chemistry lab earlier this week. We were doing a qualitative experiment (no concentration given for any solution).
I added an unknown solution that contains $\ce{Ba^2+},$ $\ce{Ca^2+},$ ...
- 205
1
vote
1
answer
2k
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Preparation of acetate buffer from sodium acetate and hydrochloric acid
A $\pu{1.0 L}$ buffer solution of $\mathrm{pH}~4.43$ is made up of $\pu{0.30 M}$ sodium ethanoate and $\pu{0.20 M}$ $\ce{HCl}$ solutions. Calculate the volume of sodium ethanoate and $\pu{0.20 M}$ $\...
2
votes
1
answer
9k
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Why do we use hydrochloric in the test for sulfate ions but nitric acid for halide ions?
Recently, I have learnt about testing for ions in qualitative analysis (BBC Bitesize).
The link above which I used for reference mentions that for the test for sulfate anions, hydrochloric acid $(\ce{...
- 235
0
votes
1
answer
161
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Redox titration or iron(II)
The concentration of $\ce{Fe^2+(aq)}$ can be determined by a redox titration using
A. $\ce{KBr}$
B. $\ce{SnCl2}$
C. $\ce{KMnO4}$ (basic)
D. $\ce{KBrO3}$ (acidic)
Can anyone please help me on this ...
- 11
2
votes
1
answer
212
views
Percent Dissociated from Titration Curve
Question 818 references the titration curve. Answer is A because $\ce{H+}$ conc $= 10^{-4}$. This is conc of dissociated acid. The conc of the undissociated acid is the original concentration minus ...
- 43
2
votes
1
answer
829
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Why is maximum buffer capacity for some diprotic buffers not when pH = pKa?
According to Rajkovic et al. [1]:
$$β = \frac{[\ce{H+}]}{K_\mathrm{w}} + 2.303\cdot\frac{[\ce{H+}]\cdot K_\mathrm{a}\cdot c}{[\ce{H+}] + K_\mathrm{a}}$$
where $K_\mathrm{a}$ is the dissociation ...
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