Question

Peste 200 g solutie de NaOH de concentratie 10% se adauga 23 g de Na. Concentratia procentuala a solutiei obtinute este?

Answer 1

C=mdx100/ms---> md= cxms/100= 10x200/100=20g NaOH
ms=md+m,apa---> mapa= 200-20g= 180g

adaugand 23g Na ,se consuma apa si apare NaOH, PRIN REACTIA

2mol......2mol..........2mol
2Na  + 2H2O-------> 2NaOH   + H2
2x23g......2x18g........2x40g
23g..........x=18g.........y=40g


m,NaOH TOTAL = 20+40=>60g=md
m,apa ramasa= 180-18=>162g
ms=md+m,apa= 60+162=> 222g
c= mdx100/ms= 60x100/222=..........................calculeaza !!!!!!