E masa atomica a metalului! Si solutia de HCl e de conc 36,5%
M + 2 HCl = MCl2 + H2
A(M)...................... Â 1 mol H2
2,8 g M...........................0,5 moli H2
A(M) = 56 Â M = Fe (din sist per)
Fe + 2 HCl = FeCl2 + H2
M(HCl) = A(H)+A(Cl) =1+35,5=36,5
56g Fe..................2*36,5g HCl
2,8 g Fe............................x
x= 3,65 g HCl = md
c/100 = md/ms
ms=100*md/c=100*3,65/36,5=10 g solutie