Which of the following statements is true regarding the pH of strong bases KOH and Ca(OH)2 given their respective pH values of 11.89 and 11.68?

• A. The pH values indicate that both solutions are neutral.
• B. Ca(OH)2 has a higher concentration than KOH.
• C. KOH has a higher concentration than Ca(OH)2.
• D. Both KOH and Ca(OH)2 have the same concentration.

Answer: (C)

Verified step by step guidance

1. Understand that pH is a measure of the hydrogen ion concentration in a solution. The lower the pH, the higher the concentration of hydrogen ions, and vice versa.
2. Recognize that strong bases like KOH and Ca(OH)2 dissociate completely in water, releasing hydroxide ions (OH⁻). The pH of a solution is related to the concentration of these hydroxide ions.
3. Recall that the pH scale ranges from 0 to 14, where a pH of 7 is neutral, below 7 is acidic, and above 7 is basic. Therefore, a pH of 11.89 and 11.68 indicates basic solutions, not neutral.
4. Compare the pH values: KOH has a pH of 11.89, which is higher than the pH of 11.68 for Ca(OH)2. A higher pH indicates a lower concentration of hydrogen ions and a higher concentration of hydroxide ions.
5. Conclude that since KOH has a higher pH than Ca(OH)2, it must have a higher concentration of hydroxide ions, meaning KOH has a higher concentration than Ca(OH)2.