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The energy profile diagram below represents a particular reaction - VCE - SSCE Chemistry - Question 13 - 2018 - Paper 1
Question 13
The energy profile diagram below represents a particular reaction. One graph represents the uncatalysed reaction and the other graph represents the catalysed reactio... show full transcript
Worked Solution & Example Answer:The energy profile diagram below represents a particular reaction - VCE - SSCE Chemistry - Question 13 - 2018 - Paper 1
Step 1
E_a uncatalysed reaction (kJ mol⁻¹)
Answer
From the energy profile diagram, we can observe the difference in energy between the reactants and the transition state for the uncatalysed reaction. The activation energy (E_a) for the uncatalysed reaction appears to be approximately 40 kJ mol⁻¹.
Step 2
E_a catalysed reaction (kJ mol⁻¹)
Answer
The energy profile also shows the activation energy for the catalysed reaction, which is lower than that of the uncatalysed reaction. This value is observed to be approximately 0 kJ mol⁻¹, suggesting very minimal energy requirement for the activated state.
Step 3
ΔH (kJ mol⁻¹)
Answer
The enthalpy change (ΔH) for the reaction is obtained by looking at the difference in energy levels between the reactants and products. The diagram indicates that the energy of the products is significantly lower than that of the reactants, thus indicating an exothermic reaction. The value for ΔH is around -50 kJ mol⁻¹.
Step 4