Question

Percentage composition Co(NO3)2

Answer 1

% composition= total wt. Of the element in one molecule*100/molecular wt.
So first find molecular wt.
Element=molecular wt.
Co(cobalt)=58.93=59
N(nitrogen)=14.01=14
O(oxygen)=16
Molecule=Co(NO3)2
Co+2*N+2*O3
59(Co)+2*14(N)+2*16(O)*3
=59+28+96=183

% composition of Co=
Wt.of copper in compound*100/molecular wt.
59*100/183=32.4% (approx.)

% composition of N=
28*100/183=15.30%(approx)

% composition of O=
96*100/183=52.45%(approx).

If you add total % the total % is 99.99 because i was round the value of atomic mass.
Thank you.