A 0.185 M solution of a weak acid (HA) has a pH of 2.95.
Calculat...

Question

A 0.185 M solution of a weak acid (HA) has a pH of 2.95.
Calculate the acid ionization constant (Ka) for the acid.

Accepted Answer

Hey everyone, we're asked, what is the acid ionization constant? For a 0.127 molar of a weak acid with a ph of 2.49 1st. Let's go ahead and write our reaction. So we have our acid and we're going to react this with water. We're going to end up with our an ion and our hydro ni um ions. We can then go ahead and create our eyes chart. Initially we were told that we had 0.127 moller of our weak acid and we had zero of our products. Initially we can go ahead and disregard our water since it's a liquid and our change for our acid is going to be minus X since we're losing reactant and plus X. On our product side. Since we're gaining products for equilibrium, we have 0.127 minus X. For acid and an X. And an X. For our products. Since we were told that our ph is 2.49, we can go ahead and use this value to determine the concentration of hydrogen ions and we can do this by taking 10 to the negative 2.49. Which is going to be our concentration of hydro ni um ions, which comes up to a value of 3. times 10 to the negative three molar. We can go ahead and use this value to solve for R. K. A. So we know that R. K. Is going to be our products over our reactant plugging in the values we just calculated, we end up with 3.2359 times 10 to the negative third molar squared. And we're going to divide this by 0.127 minus 3.2359 times 10 to the negative third molar, solving for K. A. We end up with a value of 8.5 times 10 to the negative five and this is going to be our final answer. So I hope that made sense and let us know if you have any questions.

A 0.185 M solution of a weak acid (HA) has a pH of 2.95. Calculate the acid ionization constant (Ka) for the acid.

Watch next