8.1 In Reaction 1, platinum (Pt) acts as a catalyst - NSC Physical Sciences - Question 8 - 2016 - Paper 2

The reaction is extbf{EXOTHERMIC} because the enthalpy change, ΔH, is negative (-149.1 kJ), indicating that energy is released during the reaction.

1. extbf{Increase pressure} in the reaction system to favor the formation of fewer gas molecules.
2. extbf{Add more NO or O2} to shift the equilibrium towards the production of NO2.

The value of ΔH per mole of NO2 formed is extbf{-74.55 kJ}.

The type of reaction between an acid and a base is called extbf{neutralisation} or extbf{protolysis}.

The particle transferred during the reaction is a extbf{PROTON}.

To calculate the percentage purity of the ammonium nitrate sample, first determine the number of moles of NH4NO3 that react:

$n(NaOH) = 2.4 \times 10^{-3} \text{ mol}$

Since the mole ratio between NH4NO3 and NaOH is 1:1, the moles of NH4NO3 is also: $n(NH4NO3) = 2.4 \times 10^{-3} \text{ mol}$

Now, calculate the mass of pure NH4NO3:

$m(NH4NO3) = n(NH4NO3) \times M(NH4NO3) = 2.4 \times 10^{-3} \text{ mol} \times 80 \text{ g/mol} = 0.192 \text{ g}$

Now calculate the percentage purity: $\% \text{ Purity} = \frac{0.192 \, g}{0.204 \, g} \times 100 \% = 94.12 \%$