An aqeous solution contains 10% ammonia by mass and has density of 0.99 gm cm^(-3). The pH of this solution is [Ka of NH_(3) = 5 xx 10^(-10)M]

An aqeous solution contains 10% ammonia by mass and has density of 0.9

1.	An aqeous solution contains 10% ammonia by mass and has density of 0.99 gm cm^(-3). The pH of this solution is [Ka of NH_(3) = 5 xx 10^(-10)M]
Answer» `11.033` `12.033` `9.033` `7.2033` Solution :Given, `("wt. of" NH_(3))/("wt. of solution") = (10)/(100)` `100g` solution contains `10g NH_(3)` `M_(NH_(3)) = ((10 xx 1000))/([17 xx (100//0.99)]) = 5.82` `(':. V = ("mass")/("density"))` Now, `NH_(3) + H_(2)O rarr NH_(4)OH hArr NH_(4)^(+) + OH^(-)` `"Before dissociation" ,1,0,0` `"After dissociation",(1-Calpha),Calpha,Calpha` `[OH^(-)] = C.alpha = Csqrt(((K_(b))/(C))) = SQRT((K_(b).C))` `C = 5.82 M` and `K_(b) = K_(w)//K_(a)` `= 10^(-14)//(5 xx 10^(-10)) = 2 xx 10^(-5)]` `[OH^(-)] = sqrt([2 xx 10^(-5) xx 5.82]) = 1.07 xx 10^(-2) M` `[H^(+)] = 10^(-14)//1.07 xx 10^(-2)` `= 0.9268 xx 10^(-12) M` `pH = - "log"[H^(+)] = - "log" 0.9268 xx 10^(-12) = 12.0330`.