116 г                                              Х г

    Mg(OH)2          +      H2SO4     =     MgSO4     +    2H2O

n = 1 моль                                           n = 1 моль

Mr = 58 г/моль                                     Mr = 120 г/моль

m = 58 г                                                m = 120 г

116 г Mg(OH)2    -    Х г MgSO4

58 г Mg(OH)2      -    120 г MgSO4

m(MgSO4) = 116 * 120 / 58 = 240 г