n(Na)=0,69 :23=0,03; n(Ca)=0,2 :40=0,005;
2Na+2HOH=2NaOH+H2
1 1
n(NaOH)=0,03;
NaOH=Na(+) + OH(-)
n(OH-)=0,03; m(OH-)=0,03*17=0,51;
Ca+2HOH=Ca(OH)2+H2
1 1
n(Ca(OH)2)=0,005;
Ca(OH)2 = Ca(2+) + 2OH(-)
1 2
n(OH-) =0,005*2=0,01; m(OH-)=0,01*17=0,17;
0,51+0,17=0,68;
W(OH-)=0,68 : 340=0,002(0,2%).