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

From the balanced equation, 2 moles of H₂S react with 3 moles of O₂. Therefore, the volume of oxygen needed can be calculated using the ratio:

ext{Volume of } O₂ = rac{3}{2} imes 50 ext{ cm}^3 = 75 ext{ cm}^3

To complete Figure 6:

1. Draw the profile line starting from the reactants, rising to a peak (representing activation energy), and then falling to a level below the starting point (indicating the exothermic nature of the reaction).
2. Label the peak as 'Activation energy'.
3. Indicate the difference between the starting and ending energy levels as 'Overall energy change'.

To find bond energy X for the S=O bond, follow these calculations:

1. Calculate the energy needed to break the bonds: $$ext{Bonds broken} = 4(364) + 3(498) = 2950 ext{ kJ/mol}$$
2. Calculate the energy released forming new bonds: $$ext{Bonds formed} = 2950 + 1034 = 3984 ext{ kJ/mol}$$
3. Calculate the energy for the S=O bonds formed: $$4X + 4(464) = 3984 ext{ kJ/mol}$$
4. Solve for X: $$4X = 3984 - 1856 = 2128 ext{ kJ/mol}$$

ightarrow X = 532 ext{ kJ/mol}

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