For a solution of 3.3 M H2CO3 (Ka = 4.4 × 10-7), calculate:
(a) [H+] ____?______M
(b) pH _____??______
(c) percent ionization ______?______%
To answer these questions, we need to use the concept of equilibrium and the acid dissociation constant (Ka). Let's break down each question step by step.
(a) [H+] Molarity:
The Ka value represents the equilibrium expression for the reaction of the acid with water. In this case, the reaction is H2CO3 (aq) ⇌ H+ (aq) + HCO3- (aq).
The Ka expression can be written as follows: Ka = [H+][HCO3-]/[H2CO3].
We are given the Ka value (4.4 × 10-7) and the concentration of the acid (3.3 M H2CO3). Let's assume x is the concentration of H+ formed. Since the concentration of H+ is small compared to 3.3 M, we can consider it negligible.
So, we can write the equilibrium concentration of H2CO3 as (3.3 - x) M (initial concentration - concentration of H+), and the equilibrium concentrations of H+ and HCO3- as x M.
Substituting these values into the Ka expression, we get: 4.4 × 10-7 = x * x / (3.3 - x).
Now, solve this quadratic equation for x to find the concentration of H+.
(b) pH:
Once we have the concentration of H+, we can use the equation pH = -log[H+] to calculate the pH.
(c) Percent ionization:
Percent ionization can be calculated by dividing the concentration of ionized H+ by the initial concentration of the acid (H2CO3), and then multiplying by 100.
Now, using the steps above, let's solve each question one by one.
(a) Calculation of [H+] Molarity:
Using the given Ka value and the equation mentioned above, solve the quadratic equation to find x, which represents the concentration of H+. Once x is obtained, you will have the concentration of H+.
(b) Calculation of pH:
Use the concentration of H+ obtained in the previous step to calculate the pH. pH = -log[H+].
(c) Calculation of percent ionization:
To find the percent ionization, divide the concentration of ionized H+ by the initial concentration of the acid (H2CO3), and multiply by 100. Percent ionization = (concentration of H+ / initial concentration of H2CO3) * 100.
By following these steps, you will be able to calculate the values for (a) [H+] Molarity, (b) pH, and (c) percent ionization.