Mr(NaOH) = 23 + 16 + 1 = 40
W(Na) = Ar(Na) * n / Mr(NaOH) *100% = 23 / 40 * 100% = 57,5
W(O) = Ar(O) * n / Mr(NaOH) *100% = 16 / 40 *100% = 40%
W(H) = Ar(H) *n / Mr(NaOH) *100% = 1 / 40 *100% = 2,5%
Mr(Al2O3) = 27 *2 + 16 *3 = 102
W(Al) = Ar(Al) * n / Mr(Al2O3) *100% =27 *2 / 102 *100% = 53
W(O) = Ar(O) * n / Mr(Al2O3) * 100% = 16 * 3 / 102 *100% = 47%