Răspuns:
M,Ca= 40g/mol M,Ca(OH)2=74g/mol M,H2O=18g/mol
din reactie rezulta Ca(OH)2, care se gasete dizolvat in restul de apa, formand o solutie cu anumita concentratie
1mol....2mol...........1mol sau, in grame
Ca + 2H2O----> Ca(OH)2 +H2
40g.......2x18g.........74g
20g...........x...............y
x=m,apa reactionata=18g
m,apa ramasa= 100-18=>82g
y= 37g= md
ms=md+m,apa= 37+82=> 119g
c=mdx100/ms= 37x100/119=.....................................calculeaza !!!!
Explicație:
