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1 markEnergetics

CAPE Chemistry Unit 1 · 2015 · Paper 2 · Question 1(a)(ii)

The bond lengths and bond energies of carbon-carbon single, double and triple bonds are listed. C-C: 1.54Å, 348 kJ mol⁻¹; C=C: 1.34Å, 614 kJ mol⁻¹; C≡C: 1.20Å, 839 kJ mol⁻¹.

State the relationship between the strength of a covalent bond and its length.

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Other parts of this question

  1. 1(a)(i)Define the term 'bond energy'.[1 mark]
  2. 1(b)(i)Write a balanced equation to represent the reaction above.[2 marks]
  3. 1(b)(ii)Using bond energy values from Table 1, calculate the enthalpy change of reaction, ΔHrxn, for the equation required in (b) (i).[3 marks]
  4. 1(b)(iii)Is the reaction in (b) (i) exothermic or endothermic?[1 mark]
  5. 1(b)(iv)On the axes provided below, draw the energy-profile diagram for the reaction in (b) (i).[2 marks]
  6. 1(c)Outline the experimental steps (including calculations) required to obtain an accurate value.[5 marks]

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