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3.2 Energetics

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Question 27

Two elements react to make a compound.

\mathrm{A_{2} + B_{2} \rightarrow 2AB}

The reaction is exothermic.

Which statement about the bond energies must be true?

[1]

The $A−B\mathrm{A{-}B}$ bond energy is greater than both the $A−A\mathrm{A{-}A}$ and the $B−B\mathrm{B{-}B}$ bond energies.

The $A−B\mathrm{A{-}B}$ bond energy is greater than the sum of the $A−A\mathrm{A{-}A}$ and $B−B\mathrm{B{-}B}$ bond energies.

The $A−B\mathrm{A{-}B}$ bond energy is greater than half the sum of the $A−A\mathrm{A{-}A}$ and $B−B\mathrm{B{-}B}$ bond energies.

The $A−B\mathrm{A{-}B}$ bond energy is less than both the $A−A\mathrm{A{-}A}$ and the $B−B\mathrm{B{-}B}$ bond energies.

Markscheme

3.2 Energetics Questions

GCSE
Chemistry
3.2 Energetics

51 exam-style questions on OCR GCSE Chemistry 3.2 Energetics, covering 3.2.1 Exothermic and endothermic reactions and reaction profiles and 3.2.2 Calculating energy change from bond energies. Each one has a worked solution and a mark scheme showing where the marks go.

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