Cisplatin, [Pt(NH3)2Cl2], is used as an anti-cancer drug - AQA - A-Level Chemistry - Question 4 - 2020 - Paper 3
Question 4
Cisplatin, [Pt(NH3)2Cl2], is used as an anti-cancer drug.
Cisplatin works by causing the death of rapidly dividing cells.
Name the process that is prevented by cis... show full transcript
Worked Solution & Example Answer:Cisplatin, [Pt(NH3)2Cl2], is used as an anti-cancer drug - AQA - A-Level Chemistry - Question 4 - 2020 - Paper 3
Step 1
Name the process that is prevented by cisplatin during cell division.
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Answer
The process that is prevented by cisplatin during cell division is DNA replication. Cisplatin binds to DNA, inhibiting the replication process and ultimately leading to cell death.
Step 2
Give the equation for this reaction.
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Answer
[Pt(NH3)2Cl2] + H2O → [Pt(NH3)2(H2O)]+ + Cl⁻
Step 3
Complete Figure 1 to show how the platinum complexes form a cross-link between the guanine nucleotides.
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To complete Figure 1, draw lines connecting the nitrogen atoms in the guanine nucleotides to the platinum ion in the complex ion B. This illustrates the cross-link between the two guanine nucleotides.
Step 4
Explain how graphical methods can be used to process the measured results, to confirm that the reaction is first order.
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Answer
To confirm that the reaction is first order, plot the concentration of cisplatin against time on the graph. By taking the natural logarithm of the concentration and plotting ln(concentration) instead, a straight line should be obtained. The straight-line relationship indicates that the rate of reaction is directly proportional to the concentration of the reactant, confirming first-order kinetics.
Step 5
Complete Table 1.
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Fill in the missing values in Table 1 by calculating 1/T for each temperature and ln k using the formula for the respective values.
Step 6
Calculate the activation energy, Ea, in kJ mol⁻¹.
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Answer
To calculate the activation energy using the Arrhenius equation, first plot ln k against 1/T. Determine the gradient of the line, which is equal to -Ea/R. Rearranging gives Ea = -gradient × R. Using the gradient from the graph and the gas constant, you can find Ea and convert it into kJ mol⁻¹ by dividing by 1000.