This is about the reaction between hydrogen sulfide (H2S) and oxygen - AQA - GCSE Chemistry - Question 8 - 2021 - Paper 1

From the balanced equation, 2 volumes of H2S react with 3 volumes of O2. Therefore, for 50 cm³ of H2S:

Using the ratio: rac{3}{2} = rac{V_{O2}}{50}

Rearranging gives: V_{O2} = 50 imes rac{3}{2} = 75 ext{ cm}^3

1. Draw the profile line starting from the reactants' level at the left, increasing to a peak (representing the activation energy), then decreasing to a level lower than the reactants' side (indicating it's exothermic).
2. Label the peak height as 'Activation Energy'.
3. The drop from the peak to the product level should be labeled as 'Overall Energy Change', indicating energy released in the reaction.

First, calculate total energies:

• Bonds broken: $4 imes 364 + 3 imes 498 = 2950 ext{ kJ/mol}$

• Bonds formed: $2950 + 1034 = 3984 ext{ kJ/mol}$

Setting up the equation for bonds formed:

• For the bonds formed, the energy released forming new bonds is:

  $4 imes 464 + 2X = 3984$

Solving this:

• Rearranging gives:

  $4 imes 464 + 2X = 3984$

• Calculate:

  $1856 + 2X = 3984$

  So, $2X = 3984 - 1856$

  X = rac{2128}{2} = 1064 ext{ kJ/mol}

Thus, the bond energy X for the S=O bond is 532 kJ/mol.