Răspuns:
Ca reactioneaza cu H2O si formeaza Ca(OH)2--> se formeaza o solutie de Ca(OH)2 in apa care ramane dupa desfasurarea reactiei
date; A,Ca=49g/mol miu,H2O-=18g/mol miu,Ca(OH)2= 74g/mol
40g.......2x18g............74g
Ca + 2H2O----> Ca(OH)2 +H2
20g.............x.................y
x=18g H2O----> RAMANE m,apa= 500g-18g=482g
y= 37g Ca(OH)2= masa dizolvata,md
c= mdx100/ms
md=37g
ms=md+m,apa= 37g+482g=519g
c=37x100/519=7,1%
Explicație:
