If the pH of a solution goes from 8 to 7, this means that the hydrogen ion concentration has:
(1) decreased by 1 mole/liter.
(2) increased by 1 mole/liter.
(3) decreased 10 fold.
(4) increased 10 fold
The pH scale is logarithmic, meaning that a decrease of 1 unit in pH corresponds to a 10-fold increase in hydrogen ion ([H+][H^+][H+]) concentration.
Understanding the Change in pH
- The pH drops from 8 to 7, meaning the solution is becoming more acidic.
- A decrease in pH means an increase in [H+][H^+][H+] concentration.
- Each unit decrease in pH increases [H+][H^+][H+] by a factor of 10.
Analyzing the Options
- Decreased by 1 mole/liter → Incorrect (the change is logarithmic, not linear).
- Increased by 1 mole/liter → Incorrect (the change is not exactly 1 mole/L, but a 10-fold increase).
- Decreased 10-fold → Incorrect (this would happen if pH increased).
- Increased 10-fold → Correct (since the pH decreased by 1 unit).
Final Answer:
(4) Increased 10-fold