Fireworks contain a range of chemicals including a fuel, oxidising agents and metal salts - Scottish Highers Chemistry - Question 2 - 2022

1. First, calculate the moles of potassium chlorate:

   $\text{Moles of } KCIO_3 = \frac{4.6 g}{122.6 g/mol} = 0.03752 \text{ moles}$

2. Using the balanced equation:

   $2KClO_3 → 3O_2$

   The ratio of moles of potassium chlorate to oxygen is 2:3. Thus:

   $\text{Moles of } O_2 = 0.03752 \text{ moles } × \frac{3}{2} = 0.05628 \text{ moles}$

3. Calculate the volume of oxygen produced:

   $\text{Volume of } O_2 = 0.05628 \text{ moles } × 24 \text{ L/mol} = 1.352 \text{ L}$

Thus, the volume of oxygen produced is approximately 1.35 L.

The addition of a catalyst does not change the enthalpy change of the reaction; it only increases the rate of the reaction.

1. Convert the mass of potassium per chlorate to moles:

   $\text{Moles of } KClO_4 = \frac{5.5 g}{138.6 g/mol} = 0.0397 \text{ moles}$

2. Using the energy released:

   $\text{Energy per mole} = \frac{103 kJ}{0.0397 \text{ moles}} \approx 2595.6 kJ/mol$

Increasing the temperature provides the reacting particles with more kinetic energy, resulting in more frequent collisions. This means a greater proportion of these collisions will have enough energy to overcome the activation energy barrier, leading to an increased rate of reaction.

Based on the wavelength associated with peak B, the metal responsible is likely sodium.