Răspuns:
a)
ms=400g
C=40%
md=?
md=C×ms/100=40×400/100=160gNaOH
MNaOH =23+16+1=40g/mol
MNa2SO4 =2×23+32+4×16=142g/mol
2×40g 142g
2NaOH + H2SO4 => Na2SO4 + 2H2O
160g xg
x=160×142/2×40=284gNa2SO4
b)
MNaOH =23+16+1=40g/mol
n=160/40=4moli
2moli 2moli
2NaOH + H2SO4 => Na2SO4 + 2H2O
4moli ymoli
y=4×2/2=4moli H2O