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In this experiment you will determine the enthalpy change, ΔH, for the reaction of zinc with iron(II) sulfate - CIE - A-Level Chemistry - Question 2 - 2015 - Paper 1
Question 2
In this experiment you will determine the enthalpy change, ΔH, for the reaction of zinc with iron(II) sulfate. Zn(s) + FeSO₄(aq) → Fe(s) + ZnSO₄(aq) In order to do... show full transcript
Worked Solution & Example Answer:In this experiment you will determine the enthalpy change, ΔH, for the reaction of zinc with iron(II) sulfate - CIE - A-Level Chemistry - Question 2 - 2015 - Paper 1
Step 1
Determination of the enthalpy change for the reaction of zinc, FA 4, with aqueous copper(II) sulfate, FA 6.
Answer
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Set Up the Apparatus
- Assemble a plastic cup within a 250 cm³ beaker to insulate and maintain temperature readings effectively.
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Measure the Aqueous Solution
- Use the measuring cylinder to transfer 25 cm³ of copper(II) sulfate solution (FA 6) into the plastic cup.
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Record Initial Temperature
- Measure the initial temperature of the copper(II) sulfate solution and record it accurately.
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Add Zinc
- Transfer all the zinc (FA 4) from its container into the copper(II) sulfate in the plastic cup.
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Stir the Solution
- Stir the mixture constantly until the temperature reaches its maximum reading.
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Record Maximum Temperature
- Carefully measure the maximum temperature achieved by the solution and note it down, ensuring the thermometer bulb is immersed properly.
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Calculate Temperature Rise
- Determine the temperature change ( ΔT) by subtracting the initial temperature from the maximum temperature recorded. Use the formula:
Step 2
Calculation of Energy Produced
Answer
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Energy Calculation
- Calculate the energy produced using the formula:
where 25 is the volume in cm³ and 4.2 is the specific heat capacity of water (assuming the solution behaves similarly).
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Moles of FA 6
- Calculate the moles of FA 6 using:
This results from the concentration and volume of the solution.
- Ensure the specific value calculated is at least to two significant figures.
Step 3
Step 4
Hess' Law Cycle
Answer
- Drawing Hess' Law Cycle
- Clearly label a diagram showing the displacement equations:
- The left hand downward arrow should represent the energy calculated from part (b)(iii).
- The right hand downward arrow should represent energy calculated from part (d)(ii).
- Should also adequately show that reversing the reaction results in the addition of energy rather than subtraction, consistent with Hess' Law.
- Clearly label a diagram showing the displacement equations: