What is the pH of a 0.46 mol dm⁻³ solution of potassium hydroxide at 298 K?
(Kw = 1.0 x 10^-14 mol² dm⁻⁶ at 298 K) - AQA - A-Level Chemistry - Question 10 - 2017 - Paper 3
Question 10
What is the pH of a 0.46 mol dm⁻³ solution of potassium hydroxide at 298 K?
(Kw = 1.0 x 10^-14 mol² dm⁻⁶ at 298 K)
Worked Solution & Example Answer:What is the pH of a 0.46 mol dm⁻³ solution of potassium hydroxide at 298 K?
(Kw = 1.0 x 10^-14 mol² dm⁻⁶ at 298 K) - AQA - A-Level Chemistry - Question 10 - 2017 - Paper 3
Step 1
Calculate the concentration of hydroxide ions (OH⁻)
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Answer
Given that potassium hydroxide (KOH) fully dissociates in solution, the concentration of hydroxide ions [OH⁻] is equal to the concentration of KOH. Therefore,
[OH−]=0.46moldm−3.
Step 2
Calculate the pOH
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Answer
The pOH can be calculated using the formula:
pOH=−log[OH−]=−log(0.46)≈0.34.
Step 3
Calculate the pH
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Answer
Using the relationship between pH and pOH, we know that:
pH+pOH=14.
Thus, substituting the value found:
pH=14−0.34=13.66.
Step 4
Conclusion
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Answer
Therefore, the pH of the solution is approximately 13.66.
