The results of an investigation of the reaction between P and Q are shown in this table - AQA - A-Level Chemistry - Question 10 - 2019 - Paper 3
Question 10
The results of an investigation of the reaction between P and Q are shown in this table.
Experiment Initial [P] / mol dm⁻³ Initial [Q] / mol dm⁻³ Initial rate / mol... show full transcript
Worked Solution & Example Answer:The results of an investigation of the reaction between P and Q are shown in this table - AQA - A-Level Chemistry - Question 10 - 2019 - Paper 3
Step 1
Calculate the rate for experiment 1
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Answer
The rate for experiment 1 is given as 0.400 mol dm⁻³ s⁻¹.
Step 2
Use the rate equation for experiment 1
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Answer
From the rate equation, we have:
0.400=k(0.200)(0.500)2
This simplifies to:
0.400=k(0.200)(0.25)
Thus:
0.400=k(0.050)
So,
k=0.0500.400=8
Step 3
Set up the equation for experiment 2
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Answer
Now for experiment 2, we know:
0.800=k(0.600)[Q]2
Substituting for k:
0.800=8(0.600)[Q]2
This simplifies to:
0.800=4.8[Q]2
Step 4
Solve for [Q] in experiment 2
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Answer
Rearranging gives:
[Q]2=4.80.800
Calculating:
[Q]2=0.1667
Taking the square root:
[Q]=0.1667≈0.408
Step 5
Conclusion
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Answer
The initial concentration of Q in experiment 2 is approximately 0.408 mol dm⁻³.
