Răspuns:
n=m/M
sau
n=N/NA
1.m=5,6g CaO
MCaO=ACa+AO=40+16=56g/mol
n=5,6g/56g/mol=0,1 mol CaO
2.m=392 CuSO4
MCuSO4=ACu+AS+4AO=160g/mol
n=392g/160g/mol=2,45 mol CuSO4
3. N=9,033•10²⁰ molecule H2S
n=9,033•10²⁰molecule/6,022•10²³molecule/mol=0,0015 mol H2S