[whatheck]

calculate the pH value of 0.1mole CH3COONa in water. Ka of CH3COOH = 1.8x10^-5, Kw = 1x10^-14

The equation should be CH3COONa + H2O <---> CH3COOH + NaOH, right ?

[whatheck]

i have calculated for several times and got three values, 8.26,9.26 & 11.1. Which one is correct or not above all?

[Borek]

Show how you got these values.

[whatheck]

BY pH = pK + log[salt]/[acid], putting all those numerber inside will get a <pH 7, but that should be an alkaine value. I think the problem should be the pK but anyway i don't know.

[Borek]

putting all those numerber inside

Which "all" numbers?

Hint: you have a solution of conjugate base

[rajajidwivedi]

i think it should be taken as the case of salt hydrolysis of a salt of weak acid and strong base and formula applied is
pH = 7+1/2(pka) + 1/2(logc)
where pka = -log ka = 4.74
log c = log (0.1) (assuming the volume of water is 1 litre.
 so answer should be 8.87 (approx)

[AWK]

pH = 7+1/2(pka) + 1/2(logc)

[OH^-]=SQRT(K_bxc)
[H₃O⁺]=K_w/[OH^-]=K_w/SQRT(K_bxc)=SQRT(K_w²/(K_bxc))
Hence
[H₃O⁺]=SQRT(K_wxK_a/c)
or in logarithmic scale
p[H]=1/2(pK_w+pK_a -log(c)) where p[H] means -log from concentration of [H₃O⁺]