как рассчитать малекулярную массу веществ 

H3PO4

CuCl2

H3PO4

Ca(OH)2

Al2(SO4)3

CH3COOH

M (H3PO4) = 3 + 31 + 64 = 98 
M (CuCL2) = 63 + (35 X 2) = 133
M (H3PO4) = 3 + 31 + 64 = 98
M (Ca(OH)2) = 40+ (16+3) X 2 = 118
M (Al2(SO4)3) = (27 X 2) + (32+64) x 3 = 450
M (CH3COOH) = 12+3+12+32+1=60 

М(H3PO4)= 1*3+31 +16*4=98
М(CuCl2)=64+35,5*2=135
М(Ca(OH)2)=40+(16+1)*2=74
М(Al2(SO4)3)=27*2+(32+16*4)*3=342
М(CH3COOH)=12*2+1*4+16*2=60