calculez masa de acid din solutie, stiind ro=m/v(densitatea)
c= mdx100/ms---> 49= mdx100/(200x1,84)---> md=180,32gH2SO4
calculez numarul de moli
n=m/M= 180,32/98-->1,84 molH2SO4
din reactie deduc moli gaz
2mol...........................1mol
Cu + 2H2SO4----> CuSO4 + SO2↑ + 2H2O
180,32mol....................x= 0,92moi SO2