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X and Y are solutions of two different acids - Edexcel - GCSE Chemistry - Question 9 - 2019 - Paper 1

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X and Y are solutions of two different acids. The concentration of acid in each solution, in mol dm⁻³, is the same. Solution X has a pH of 3.40 and solution Y has a ... show full transcript

Worked Solution & Example Answer:X and Y are solutions of two different acids - Edexcel - GCSE Chemistry - Question 9 - 2019 - Paper 1

Step 1

State what could be used to measure these pH values of 3.40 and 4.40.

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Answer

To measure the pH values of 3.40 and 4.40, a pH meter or a pH probe can be used. Additionally, universal indicator or pH paper can also serve this purpose. However, using specific terms like 'indicator' without specification would not be acceptable.

Step 2

What is the concentration of hydrogen ions in solution X compared with that in solution Y?

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Answer

To compare the concentration of hydrogen ions, we need to understand the pH scale. The formula relating pH to hydrogen ion concentration is:

[H+]=10−pH[H^+] = 10^{-pH}

For solution X with a pH of 3.40:

[H+]X=10−3.40[H^+]_X = 10^{-3.40}

For solution Y with a pH of 4.40:

[H+]Y=10−4.40[H^+]_Y = 10^{-4.40}

To find the ratio of the concentrations:

[H+]X[H+]Y=10−3.4010−4.40=10(4.40−3.40)=101=10\frac{[H^+]_X}{[H^+]_Y} = \frac{10^{-3.40}}{10^{-4.40}} = 10^{(4.40 - 3.40)} = 10^{1} = 10

Thus, the hydrogen ion concentration in solution X is ten times higher than that in solution Y. The correct answer is D.

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