m HCl = w HCl*m раствора/100\% = 10\%*150г/100\% = 150г*0,1 = 15г
Ca + 2HCl = CaCl2+H2
2Mg+O2=2MgO
2H2S+3O2=2H2O+2SO2
Fe2O3+3H2=2Fe+3H2O
CaCl2+2NaOH=Ca(OH)2+2NaCl