In momentul in care se adauga Na in apa, acesta reactioneaza cu ea si formeaza o solutie de NaOH cu restul de apa ce a ramas dupa reactie
p/100=m,pur/m,impur
m,pur= 20gx92/100= 18,4g
2mol 2mol 2mol
2Na + 2 H2O------> 2NaOH + H2
2x23g......2x18g..........2x40g
18,4g......m=14,4g.......32g
md=m,NaOH= 32g
m,apa= 200g-14,4g=185,6g
ms= md+m,apa= 32g+185,6g=217,6g
c= mdx100/ms
inlocuieste si calculeaza C !!!!!