Answer:
1. Decrease the pH
2. The pH remains unchanged
3. Decrease the pH
Explanation:
We can calculate the pH of a weak acid using the following expression:
[1]
where,
Ka is the acid dissociation constant
Ca is the initial concentration of the acid
<em>State whether each of the following would increase, decrease, or leave the initial pH unchanged and explain your reasoning</em>
- <em>Using the same weak acid, but having a higher concentration. </em>According to eq. [1], a higher Ca leads to a higher [H⁺] and a lower pH.
- <em>Using 80.00 mL of this weak acid instead of 40.00 mL.</em> pH refers to a concentration, which is an intensive property, so it does not change when we change the amount of matter.
- <em>Using a different weak acid that has a larger Ka value.</em> According to eq. [1], a higher Ka leads to a higher [H⁺] and a lower pH.