Answer
$M=245.7\ g/mol$
Mass percents:
Cu: $25.86\%$
N: $22.80\%$
H: $5.70\%$
S: $13.05\%$
O: $32.55\%$
In 10.5 g of the compound:
Cu: $2.72\ g$
$H_2O$: $0.770\ g$
Work Step by Step
Atomic weights (g/mol): $Cu: 63.546,\ N: 14.007,\ H:1.0079,\ S:32.06,\ O:15.999$
Molar mass of $Cu(NH_3)_4SO_4\dot{}H_2O$:
$M=63.546+4\times14.007+14\times1.0079+32.06+5\times15.999=245.7\ g/mol$
Mass percents:
Cu: $63.546/245.7\times100\%=25.86\%$
N: $4\times14.007/245.7\times100\%=22.80\%$
H: $14\times1.0079/245.7\times100\%=5.70\%$
S: $32.06/245.7\times100\%=13.05\%$
O: $5\times15.999/245.7\times100\%=32.55\%$
In 10.5 g of the compound:
Cu: $10.5\ g\times\frac{25.86}{100}=2.72\ g$
The molar mass of water is $18.015\ g/mol$:
$H_2O$: $10.5\ g\times\frac{18.015}{245.7}=0.770\ g$
