Question

Calculate the ph of 0.01m solution of nh4cn

Answer 1

pH=7+1/2 [pka-pkb]

pka=-log ka
=>-log (6.2×10^-10)
=>10-log (6.2)
=>10-0.79=9.21

pkb=-log kb
=>-log (1.6× 10^-5)
=> 5- log (1.6)
=>5-0.20=4.8

=>7+1/2[9.21-4.8]
=>7+1/2 [4.41]
=>7+2.205=9.205 ~9.21

Answer 2

Hey dear,
You have given incomplete data. I'll add that to given section.

● Answer -
pH = 9.2


● Explaination -
# Given -
C = 0.01 M
ka(HCN) = 6.2×10^-10
kb(NH3) = 1.6×10^-5

# Solution -
To calculate pKa -
pKa = -log(Ka)
pKa = -log(6.2×10^-10)
pKa = 9.2

Yo calculate pKb -
pKb = -log(Kb)
pKb = -log(1.6×10^-5)
pKb = 4.8


pH of the solution is calculated by -
pH = 1/2 (pKw + pKa - pKb)
pH = 1/2 (14 + 9.2 - 4.8)
pH = 9.2

Therefore, pH of 0.01 M NH4CN is 9.2

Hope this helps you...