Question

In ce masa de H2O se gasesc 32 g Oxigen

Answer 1

Masa molara  H2O = AO + 2 ori AH = 16 + 2 = 18g/mol

in 18g apa ... 16g oxigen

in x g apa ... 32g oxigen

x=32 ori 18 pe 16

x=2 ori 18

x=36

Answer 2

32g oxigen

mH2O =?

-se afla masa molara a apei

M=2 + 16=18------> 18g/moli

-se scrie rationamentul :

18g H2O-------------16g O

xgH2O ------------32g O

x=18.32 : 16=36g H2O   [ nr.moli=n=36g: 18g/moli=2moli H2O ]