Question

The % of N in 66% pure (NH 4)2SO4 sample is -

Answer 1

We Know that atomic weight of (NH4)2 SO4 = 14 * 2 * 4 * 2  + 32 * 16 * 4

                                                                           = 132 grams. 


 % of N = 28/132 * 100 = 21.2%

% of N in 66% is 67/100 * 21.2=14%


Hope this helps!

Answer 2

First we will have to calculate the molar mass of the compound that is :
for nitrogen =14*2=28grams
hydrogen 4*2=8grams
sulphur 32 grams
oxygen 16*4=64gram
That is molar mass of NH42SO4 will be addition of masses of
all these elements = 132grams
Therefore % of nitrogen in this compound = 28/132 *100* 66/100
14%