pH of given buffer solution prepared by dissolving 0.20 mole of cyanic acid is 4.30.
Solution:
Equilibrium reaction equation for the given reaction is as follows. HCNO(aq) + H2O(l) → CNO (aq) + H₂O* (aq)
It is given that initial moles of HCNO is 0.20 mol and for NaCNO is 0.80 mol.
Ka of HCNO Is 2 x 10^-4 mol.
Now, we will assume that at equilibrium there are x moles.
HCNO(aq) + H2O(l) → CNO (aq) + H₂O+ (aq)
Initial: 0.20 0.80 0
Change: -x +x +x
Equilibrium: 0.20-x 0.80 + x x
As the volume of the given solution is 1 liter, equilibrium concentration and moles are same.
Ka = [CNO-][H30+]/[HCNO]
2.0x 10^-4 = x(0.80 + x) / (0.20 - x)
x = 5.0x10^-5 M
Then, pH = -log[H30+]
= -log(5.0 × 10^-5)
= 4.30
pH of given buffer solution is 4.30.
A weak acid and either its conjugate base or the base itself are combined in an aqueous solution to form a buffer solution. The pH scarcely changes at all when a small amount of a strong acid or basic is added to it.
To learn more about buffer solution visit:
https://brainly.com/question/24262133
#SPJ4
