f.4 chemistry
2015-05-31 7:20 am
1) A sample of paint pigment of mass 1.50g is dissolved and the lead(II) ions in it are separated by precipitation as lead(II0 sulphate. The precipitate has a mass of 0.0849g. What is the percentage by mass of lead in the pigment? (show steps please!!!!)
回答 (1)
2015-05-31 6:52 pm
✔ 最佳答案
1.Molar mass of Pb = 207.2 g/mol
Molar mass of PbSO4 = 207.2 + 32.1 + 16×4 = 303.3 g/mol
Mass of Pb in PbSO4 = 0.0849 × (207.2/303.3) = 0.0580 g
Mass of Pb in the sample = 0.0580 g
% by mass of Pb in the sample = (0.0580/1.50) × 100% = 3.87%
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