7,8 г                                                            Х л 2K        +         2H2O       =       2KOH     +   H2n = 2 моль                                                  n = 1 мольMr = 39 г/моль                                           Vm=22,4 л/мольm = 78 г                                                      V = 22,4 л7,8 г К     -     Х л Н278 г К      -     22,4 л Н2V(H2) = 7,8 * 22,4 / 78 =2,24 л