M,Ca= 40g/mol M,Ca(OH)2= 74g/mol M,H2= 2g/mol
1mol...2mol..........1mol........!mol sau, in grame
Ca + 2H2O----> Ca(OH)2 + H2
40g...2x18g............74g...........2g
8g.........x..................y................z
z= 0,4gH2
x= 7,2gH2O,,,,,,,...ramane m,apa= 200g-7,2g
y= 14,8g Ca(OH)2.......aceasta masa se dizolva in masa de apa ramasa si formeaza o solutie
md= 14,8g
ms= md+m apa= 14,8g+(200-7,2) g
c= mdx100/ms INLOCUIESTE SI CALCULEAZA !!!!