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1 markEnergetics

CAPE Chemistry Unit 1 · 2015 · Paper 2 · Question 1(b)(iii)

Bond energies can be used to estimate the enthalpies of reactions. Consider the gas-phase reaction between methane (CH₄) and chlorine to produce methyl chloride (CH₃Cl) and hydrogen chloride.

Is the reaction in (b) (i) exothermic or endothermic?

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Other parts of this question

  1. 1(a)(i)Define the term 'bond energy'.[1 mark]
  2. 1(a)(ii)State the relationship between the strength of a covalent bond and its length.[1 mark]
  3. 1(b)(i)Write a balanced equation to represent the reaction above.[2 marks]
  4. 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]
  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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