p=m pur/ m impur*100 => mpur=p*m impur/100 =63*200/100=126g MgCO3
MMgCO3=AMg+AC+3AO=24+12+3*16=84g/mol
MH2SO4=2AH+AS+4AO=2*1+32+4*16=98g/mol
MgCO3 + H2SO4 = MgSO4 + H2CO3 (CO2+H2O)
84g MgCO3...................98g H2SO4
126g MgCO3...................xg
x=126*98/84= Calculeaza !!