Calculating Van't Hoff Factor of a Weak Acid
1. Given Information:
- Concentration of acid (HA): 1M
- pH of the solution: 0.2
2. Calculating the Van't Hoff Factor:
The Van't Hoff factor (i) is a measure of the number of particles into which a compound dissociates in a solution. For a weak acid like HA, it partially dissociates into its ions.
3. pH Calculation:
The pH of a solution is given by the formula: pH = -log[H+]
Given pH = 0.2, [H+] = 10^(-0.2) = 0.63 M
For a weak acid, [HA] = [H+] as it partially dissociates.
4. Dissociation of HA:
The dissociation reaction of HA can be represented as:
HA ⇌ H+ + A-
5. Van't Hoff Factor Calculation:
Since 1M of HA dissociates into 0.63M of H+ ions, the Van't Hoff factor is calculated as:
i = (1M)/(0.63M) = 1.59
6. Interpretation:
The Van't Hoff factor of the weak acid HA is approximately 1.59. This value indicates that HA partially dissociates in the solution, leading to an increase in the number of particles present compared to the initial concentration of the acid.
In conclusion, understanding the concept of Van't Hoff factor is crucial in determining the extent of dissociation of a compound in a solution, especially for weak acids like HA.