|
|
Gravimetric Analysis |
Experiment 1 Online Tutorial >> Gravimetric Analysis >> Step 3: Tutor 1
Experiment 1 - Gravimetric AnalysisStep 3: Calculating the amount of Pb2+ in the initial sample.In step three we weigh the mass of the final solid and calculate the amount of lead in the original sample.
The unknown sample was found to weigh 0.8758 g. The lead sulfate precipitated from the sample weighed 0.5323 g. What is the % lead in the unknown? (Please give your answer to 4 significant figures)
Hint
% Pb
Good Job!
That's not quite right.
Hint:
If you are having trouble, scroll below to get step by step help in solving this problem.
The following tutors are a step by step walkthrough that show the details on how to solve the above problem.
The mass of lead in lead sulfate is equal to the mass of lead in the unknown sample. Similarly, the number of moles of lead in lead sulfate is equal to the number of moles of lead in the unknown sample. How many moles of lead are there in our 0.5323 g of lead sulfate? (Note: the MW of PbSO4 is 303.258 g/mol)
Hint
Moles PbSO4
Good Job!
That's not quite right.
Hint:
There is 1 mole of lead in each mole of lead sulfate.
get next hint
Hint:
How do you convert mass of lead sulfate to moles of lead sulfate?
get previous hint
get next hint
Hint:
To convert mass of lead sulfate to moles of lead sulfate, use the Molecular Weight of PbSO4, 303.258 g/mol
get previous hint
get next hint
Hint:
The result is 0.5323 g / 303.258 g/mol = 0.001755 mol
get previous hint
How many moles of lead are there in the unknown sample?
Hint
moles Pb
What is the mass of lead in the unknown sample?
grams Pb
Good Job!
That's not quite right.
Hint:
In one mole of PbSO4 there is one mole of lead, how many moles of lead are there in the unknown sample?
get next hint
Hint:
There are 0.001755 moles of lead in the unknown sample.
get previous hint
Hint:
How do you convert moles of lead to mass of lead?
get next hint
Hint:
To convert from moles of lead to mass of lead use the atomic weight of Pb, 207.2 g/mol.
get previous hint
get next hint
Hint:
The result is: (0.001755 mol Pb) * (207.2 g/mol Pb) = 0.3636 g Pb.
get previous hint
What is the percentage of lead in the unknown sample?
Hint
% Pb
Good Job!
That's not quite right.
Hint:
To calculate percentage of lead in the sample, divide the mass of lead by the mass of sample and multiply by 100%.
get next hint
Hint:
The result is: (mass of lead / mass of sample) x 100 =
(0.3636g / 0.8758g) x 100 = 41.52%. get previous hint
|
| Last Updated: Sunday, November 13th, 2022 @ 07:12:28 pm |