V.H2= 1ml
n,H2=V/Vm= 1ml/22,4l/mmol=.................
pH indica mediul acid
Fe-2e----> Fe²⁺
2H⁺+2e----> H2
Fe +2H⁺----> Fe²⁺ + H2 sau
Fe + 2HCl---> FeCl2 + H2
1mmol........................1mmol
x................................1/22,4mmol
x=n= 1/22,4mmol Fe
m,Fe= nxM=1/22,4mmolx56mg/mmol=....................calculeaza