Calculate the pH at the following points during the titration of 100.0ml of 0.20 M acetic acid (ka for acetic acid=1.8*10^-5) with 0.10 M sodium hydroxide.

1. Before addition of any base
2. after addition of 30.0 mL of base

HA ==> H^+ + A^=

Set up an ICE chart for acetic acid, substitute into Ka expression and solve for H^+, then convert to pH.
2. Use the same ICE chart and add 30.0 mL x 0.1M NaOH and recalculate the H^+ and pH. Don't forget the dilution by the extra 30.0 mL of NaOH>

To calculate the pH during a titration, we need to consider the reactions happening between the acid and base and how they affect the concentration of hydrogen ions (H+). Here's how you can calculate the pH at the given points:

1. Before addition of any base:
Before the addition of any base, the solution only contains acetic acid. To calculate the pH, we need to determine the concentration of H+ ions from the dissociation of acetic acid.
The equation for the dissociation of acetic acid is: CH3COOH (acetic acid) ⇌ H+ + CH3COO-
Since acetic acid is a weak acid, it only partially dissociates in water.

To calculate the concentration of H+ ions, we need to consider the initial concentration of acetic acid (0.20 M) and the equilibrium constant (Ka = 1.8 * 10^-5).

Ka = [H+][CH3COO-] / [CH3COOH]

From the equation, we can see that initially [H+] = [CH3COO-].

Let x be the concentration of H+ ions in mol/L.
Using the equilibrium constant expression, we can set up the following equation:

1.8 * 10^-5 = x^2 / 0.20

Solving this equation will give us the concentration of H+. Once we have the concentration of H+, we can calculate pH using the equation:

pH = -log[H+]

2. After addition of 30.0 mL of base:
To calculate the pH after adding 30.0 mL of base, we need to determine how much of the base reacts with the acetic acid. The reaction between acetic acid and sodium hydroxide can be represented as follows:

CH3COOH + NaOH ⇌ CH3COONa + H2O

Since the balanced equation is 1:1, the moles of acetic acid that react with sodium hydroxide will be equal to the moles of sodium hydroxide added. Using the molarity and volume of sodium hydroxide solution added (0.10 M and 30.0 mL), calculate the moles of sodium hydroxide added.

Next, determine the moles of acetic acid in the original solution. With the initial concentration (0.20 M) and initial volume (100.0 mL), calculate the moles of acetic acid.

Subtract the moles of sodium hydroxide reacted from the initial moles of acetic acid to find the remaining moles of acetic acid.

Finally, calculate the concentration of acetic acid using the remaining moles and the final volume of the solution after the addition of the base.

Now that we have the concentration of acetic acid, we can perform the same steps we did in the first point to determine the pH.

Remember to use the equation: pH = -log[H+] to find the pH for each point in the titration.