Weak acid. pH = ?

0 ⤊

What is the ph of 0.1 M HCN?

2007-09-21 23:13:18 · 2 answers · asked by Anonymous in Science & Mathematics ➔ Chemistry

2 answers

Ka = 4 x 10^-10
HCN <-----> H+ + CN-
initial concentration
0.1
change
-x . .. . . . . . . +x .. . +x
at equilibrium
0.1-x. . . . . . . . x . . .. .x
4 x 10^-10 = x^2 / 0.1-x
x = [H+] = 6.3 x 10^-6 M
pH = - log 6.3 x 10^-6 = 5.2

2007-09-21 23:17:39 · answer #1 · answered by Dr.A 7 · 0⤊ 0⤋

-log of root (0.1 x Ka for HCN).

Now you can work it out.

2007-09-21 23:16:36 · answer #2 · answered by Gervald F 7 · 0⤊ 0⤋