A student measures the pH of four solutions: 2, 6, 7, and 11. Which solution will have the highest hydroxide ion concentration?
Answer and explanation
Correct answer: Solution with pH 11
At 25°C, pH and pOH are related by pH + pOH = 14, and hydroxide concentration increases as pOH decreases. For pH 11, pOH is 3, so [OH⁻] is about 10⁻³ mol L⁻¹. The pH 7 solution is neutral, while pH 6 and pH 2 are acidic and have much lower hydroxide concentrations. Hence the pH 11 solution has the highest [OH⁻].
Frequently asked questions
What is the correct answer to this question?
Solution with pH 11
Why is this the correct answer?
At 25°C, pH and pOH are related by pH + pOH = 14, and hydroxide concentration increases as pOH decreases. For pH 11, pOH is 3, so [OH⁻] is about 10⁻³ mol L⁻¹. The pH 7 solution is neutral, while pH 6 and pH 2 are acidic and have much lower hydroxide concentrations. Hence the pH 11 solution has the highest [OH⁻].
Which subject and chapter does this question cover?
This is a Class 10 Science question. Chapter: Chemical Substances – Nature and Behaviour. Topic: Acids, Bases, and Salts.
