Final answer:
To calculate the Ka value of HX, you need to use the percentage of dissociation and the concentration of the weak acid. The equation for calculating Ka is Ka = [H+][X-]/[HX]. To find the percentage of dissociation in a different concentration solution or the concentration at a specific percentage of dissociation, you can rearrange the equation and solve for x using the given information.
Step-by-step explanation:
To calculate the Ka value of HX, we need to use the percentage of dissociation and the concentration of the weak acid. The equation for calculating Ka is: Ka = [H+][X-]/[HX]. Since the weak acid is 3.2% dissociated in a 0.025 M solution, we can calculate the concentration of [H+] and [X-] using 3.2% of 0.025 M. Let's assume x is the concentration of [H+] and [X-].
Then, Ka = (x)(x)/(0.025 - x) = 3.2/100. Solve for x using this equation and you will find the value of x and determine the Ka value of HX.
To calculate the percentage of dissociation in a 0.050 M solution, you can use the same equation and solve for x using the given concentration. The percentage of dissociation is then given by (x/0.050) * 100.
To find the concentration at which the acid is dissociated 4.0%, you can rearrange the equation mentioned earlier and solve for x using 4.0% of the initial concentration. The concentration at 4.0% dissociation is then given by x.