1. Masa H2O=2*AH +AO=2*1+16=2+16=18g/mol
deci in 18g H2O sunt 2g H
90g.................x
x=2*90/18=180/18=10G
2. Masa H2SO4=2*1+32+4*16=2+32+64=98g/mol
Masa a 10 moli H2S04=10*98=980
2....32....64.....98
h.....s.....o.......980
h=980*2/98=20g H
s=980*32/98=320g S
o=980*64/98=640g O