Mr( SO3)=32+16*3=80
w(S)= 32:80=0,4 (4%)
w(O)=(16*3):80= 0,6 (6%)
Mr(H2SO4)= 1*2+32+16*4=98
w(H)= (1*2):98=0,02(2%)
w(S)=32:98=0,33(33%)
w(O)=(16*4):98=0,65 (65%)
Mr(Al(NO3)3)= 27+(14+16*3)*3=213
w(Al)= 27:213=0,13 (13%)
w(N)= 14:213=0,06(6 %)
w(O)=(16*3): 213=0,23(23%)