2 задание. Относительная молекулярная масса.
1) Mr(Fe(OH)3) = Ar(Fe) + Ar(O)*3 + Ar(H)*3 = 56 + (16*3) + (1*3) = 56 + 48 + 3 = 107
2) Mr(Al2(SO4)3 = Ar(Al)*2 + Ar(S)*3 + Ar(O)*12 = (27*2) + (32*3) + (16*12) = 81 + 96 + 192 = 369
3) Mr((CH3COO)2Pb) = Ar(C)*2 + Ar(H)*6 + Ar(C)*2 + Ar(O)*2 + Ar(O)*2 + Ar(Pb) = (12*2) + (1*6) + (12*2) + (16*2) + (16*2) + 207 = 24 + 6 + 24 + 32 + 32 + 207 = 325
4) Mr(NaO) = Ar(Na) + Ar(O) = 23 + 16 = 39
5) Mr((NH4)2SO4) = Ar(N)*2 + Ar(H)*8 + Ar(S) + Ar(O)*4 = (14*2) + (1*8) + 32 + (16*4) = 28 + 8 + 32 + 64 = 132
Задание 3.
W = Ar(химического элемента)*n \ Mr(вещества) * 100%
1) Ca3(PO4)2
Mr(Ca3(PO4)2) = Ar(Ca)*3 + Ar(P)*2 + Ar(O)*8 = (40*2) + (31*2) + (16*8) = 80 + 62 + 128 = 270
a) W(Ca3) = Ar(Ca)*3 \ Mr(Ca3(PO4)2 * 100% = 80\270 * 100% = 30%
b) W(P2) = Ar(P)*2 \ Mr(Ca3(PO4)2) * 100% = 62\270 * 100% = 20%
c) W(O8) = Ar(O)*8 \ Mr(Ca3(PO4)2)* 100% = 128\270 * 100% = 70%
2) Na2SO4
Mr(Na2SO4) = Ar(Na)*2 + Ar(S) + Ar(O)*4 = (23*2) + 32 + (16*4) = 46 + 32 + 64 = 142
a) W(Na2) = Ar(Na)*2 \ Mr(Na2SO4) * 100% = 46\142 * 100% = 30%
b) W(S) = Ar(S) \ Mr(Na2SO4) * 100% = 32\142 * 100% = 20%
c) W(O) = Ar(O)*4 \ Mr(Na2SO4) * 100% = 64\142 * 100% = 50%