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

First, calculate the number of moles of KClO₃:

$\text{Moles of } KClO₃ = \frac{4.6 \text{ g}}{122.6 \text{ g/mol}} = 0.03752 \text{ moles}$

From the balanced equation, 2 moles of KClO₃ produce 3 moles of O₂:

$\text{Moles of } O₂ = 0.03752 \text{ moles KClO₃} \times \frac{3 ext{ moles O₂}}{2 ext{ moles KClO₃}} = 0.05628 \text{ moles O₂}$

Next, calculate the volume of O₂ produced:

$\text{Volume of } O₂ = 0.05628 \text{ moles} \times 24 \text{ L/mole} = 1.3524 \text{ L}$

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

Adding a catalyst does not affect the enthalpy change for the reaction; it only speeds up the reaction rate without changing the overall energy change.

First, calculate the number of moles of potassium perchlorate:

$\text{Moles of } KClO₄ = \frac{5.5 \text{ g}}{138.6 \text{ g/mol}} = 0.0397 \text{ moles}$

Next, calculate the energy released per mole:

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

Increasing temperature increases the rate of a chemical reaction due to a rise in the energy of the particles involved. This leads to:

1. An increased number of particles having energy equal to or greater than the activation energy, thus facilitating more successful collisions.
2. A greater frequency of collisions between reactants, increasing the likelihood of reaction. As a result, the overall rate of reaction increases.

The metal responsible for peak B on the spectrum is likely Sodium, which emits a characteristic yellow light.