For a week acid whose ionization constant is 1.75 x 10(-5), the pH of its solution is 3.0. Determine its degree of ionization and its percent ionization.
HA ==> H^+ + A^-
Ka = (H^+)A^-)/(HA)
Set up an ICE chart and solve for (HA). Then
%ion = [H^+)/(HA)]*100 = ?
degree ion = %ion/100.
To determine the degree of ionization and percent ionization of an acid, we first need to understand the concept of ionization constant and pH.
The ionization constant (Ka) is a measure of the strength of an acid. It represents the equilibrium constant for the ionization reaction of the acid in water. The smaller the value of Ka, the weaker the acid.
The pH scale is a measure of the acidity or basicity of a solution. It ranges from 0 to 14, where 0-6 indicates acidity, 7 is neutral, and 8-14 indicate basicity. The pH is related to the concentration of hydrogen ions (H+) in the solution.
Now let's calculate the degree of ionization and percent ionization using the given data:
Step 1: Convert the given Ka value to concentration (molarity):
Ka = [H+][A-] / [HA]
1.75 x 10^(-5) = [H+]^2 / [HA]
Since the acid is weak, we can assume that the concentration of [H+] after ionization is x. Therefore, the concentration of [HA] will be the initial concentration minus x:
[H+] = x
[HA] = Initial concentration - x = Initial concentration - [H+]
Step 2: Calculate [H+] from the pH:
pH = -log[H+]
3.0 = -log[H+]
Take the antilog of both sides to find [H+]:
[H+] = 10^(-pH)
Step 3: Determine the degree of ionization:
The degree of ionization (α) represents the fraction of the initial acid that has ionized. It can be calculated using the equation:
α = [H+] / Initial concentration
Step 4: Calculate the percent ionization:
The percent ionization is the degree of ionization expressed as a percentage:
Percent Ionization = α * 100
With these steps in mind, we can now proceed to calculate the degree of ionization and percent ionization.