Question

Calculati cantitatea de solutie de NaOH 20% necesara ptr. neutralizarea a 4,4 g amestec de acid clorhidric si acid sulfuric, daca ptr. precipitarea clorului din amestec se consuma 68 g de solutie de azotat de argint 10 %.

Answer 1

AgNO3 + HCl ---> AgCl + HNO3
c%=md/ms*100=>md=68*10/100=6,8 g AgNO3
170 g AgNO3......36,5 g HCl
6,8 g AgNO3............x             x = 1,46 g HCl => m H2SO4 = 4,4-1,46=2,54 g
NaOH + HCl ---> NaCl + H2O
40 g NaOH.......36,5 g HCl
a g NaOH.........1,46 g HCl         a = 1,6 g NaOH 
2 NaOH + H2SO4 ---> Na2SO4 + 2 H2O
2*40 g NaOH..........98 g H2SO4
b g NaOH..............2,54 g H2SO4        b = 2,07347 g NaOH
masa totala NaOH = md = 1,6 + 2,07347 = 3,67347 g
c%=md/ms*100=>ms=20/3,67347*100=> ms NaOH = 544,44 g NaOH solutie