-calculez masa si moli HCl din solutie, stiind M,HCl= 36,5g/mol
c= mdx100/ms---> md= 36,5x400/100g HCl=36,5X4 g HCl
niu= m/M= 36,5x4g/36,5 g/mol= 4molHCl
-calculez moli H2 din ecuatia chimica
2mol............................1mol
Zn + 2HCl----> ZnCl2 + H2
4mol...................................x=2molH2
-daca se cere masa de hidrogen.
m= niuxM=2molx2g/mol-=4g
-daca se cere volumul
V=niuxVm= 2molx22,4 l/mol= 44,8 l