Use the “Dilution” step (from the 8.4 daily videos) first, whenever combining two solutions. Second, use these diluted concentrations to perform the first neutralization, involving the strong acid or base.
Then, use the results of this neutralization to decide what to do:
If there is leftover strong acid or base, use that remaining concentration to determine pH (pHun zone).
If there is no leftover strong acid or base, use the remaining concentrations of weak acid/base conjugates in the “Initial” line of your ICE tables (Ka or Kb of weak acid or base).

Strong Acid - Strong Base: You have 50. mL of a 0.15 M nitric acid solution (HNO3).
Determine the pH of this solution.
To it, you add a 0.30 M sodium hydroxide solution (NaOH). Determine the pH after…
15 mL are added
25 mL are added
40. mL are added
At any point during these additions, is the mixture a buffer solution? Why or why not?

Weak Acid - Strong Base: You have 50. mL of a 0.15 M nitrous acid solution (HNO2, Ka = 4.0x10-4).
Determine the pH of this solution.
To it, you add a 0.30 M sodium hydroxide solution (NaOH). Determine the pH after…
15 mL are added
25 mL are added
40. mL are added
At any point during these additions, is the mixture a buffer solution? If yes, when? Why?

Weak Base - Strong Acid: You have 30. mL of a 0.20 M aniline (C6H5NH2, Kb = 3.8x10-10).
Determine the pH of this solution.
To it, you add a 0.30 M hydrochloric acid solution (HCl). Determine the pH after…
10. mL are added
20. mL are added
30. mL are added
At any point during these additions, is the mixture a buffer solution? If yes, when? Why?