Răspuns:
n= m . M ; n= nr. moli ; m= masa subst.; M= masa molara
Explicație:
a.
xmoli 5moli ymoli zmoli
2NaOH + H2SO4 = Na2SO4 +2 H2O
2moli 1mol 1mol 2moli
x= 5 .2=10 moli NaOH
MNaOH= 23+ 16 +1=40-------> 40g/moli
m= 10moli . 40g/moli= 400 g NaOH
b.
y= 5moli Na2SO4
c.
z= 5.2=10 moli H2O
MH2O= 2+16=18------->18g/moli
m= 10moli. 18g/moli= 180 g H2O
1mol H2O----------6,023.10²³molecule H2O
10 moli --------------x
x= 10 . 6,023 .10²³= 60,23 .10²³molecule H2O
d.
1mol Na2SO4-------------4 . 6,023.10²³ atomi O
5moli------------------------------------------x
x= 5 . 4 . 6,023.10²³ atomi de O =120 ,46 . 10²³ atomi O
1mol H2O------------6,023.10²³atomi O
10 moli -----------------------------y
y= 10 . 6,023.10²³atomi O= 60, 23.10²³atomi O
nr. total de O= 120 ,46 .10²³ + 60, 23.10²³=180,69.10²³atomi O