Question

A 0.8552g sample of copper alloy is treated with 8 molar nitric acid and filtered and the precipitate is ignited giving a residue of 0.0632g of SnO2. The zinc is determined in one half of the filterate by precipitating it as ZnNH4PO4 and then igniting with 0.2231g of Zn2P2O7 is formed. In the other half of the filterate copper is determined as CuSCN giving a precipitate of 0.5874g. Calculate the percentage tin, zinc and copper in the sample.

Answer 1

% metal in sample = (mass metal/mass sample)*100 = ?

mm stands for molar mass.am is atomic mass.

mass Sn = mass SnO2 ppt x (am Sn/mm SnO2) = ?

mass Zn2P2O7 in 1/2 sample is 0.2231 and x 2 = mass Zn2P2O7 in all of the sample.
mass Zn = mass Zn2P2O7 x (2*am Zn/mm Zn2P2O7)*100 = ?

mass CuSCN in 1/2 sample is 0.5874 and x 2 = mass CuSCN in whole sample.
Mass Cu = mass CuSCN x (am Cu/mm CuSCN)*100 = ?

Post your work if you get stuck.

Answer 2

% SN = [mass SnO2/mm] * mm Sn
-------------------------------------* 100 =
Sample


5.82% Zn

Answer 3

You must have made a typo. 5.82% Sn is correct.

Answer 4

I'm lost when I find% Zinc and copper, how is the stoichiometry of the reaction?