Răspuns:
n=nr.moli ; m=masa subst. (g ) ;M=masa molara (g/moli )
Explicație:
0,5moli MgO
g MgO
g,moli Mg
xmoli 0,5moli
2Mg + O2=2MgO
2moli 2moli
x=0,5 . 2 : 2=0,5moli Mg
n=m :M
m= n . M
m=0,5moli . 24g/moli=120g Mg
m=0,5moli .40g.moli=20g MgO
MMgO=24+16=40----->40g/moli