Răspuns:
Na reactioneaza cu apa si formeaza NaOH, care se dizolva in restul de apa ramas la sfarsitul reactiei
-din ecuatia reactiei deduc masa de NaOH format si masa de apa reactionata
2Na + 2H2O-----> 2NaOH + H2
2x23g.....2x18g........2x40g
2,3g...........x................y
x=m=1,8g H2O
y=m=4gNaOH
-
C=mdx100/ms
md= y=4gNaOH
ms=md+m,apa=4+m,apa
m,apa=m,initiala -m,reactionata=72-1,8=>70,2g
ms= 4+70,2=> 74,2g
c= 4x100/74,2=5,4%
Explicație:
