1.1. Many vehicles are fitted with airbags which provide a gas-filled safety cushion to protect the occupant of the vehicle if there is a crash.

The first reaction in airbags is the thermal decomposition of sodium azide, NaN₃, to form sodium and nitrogen gas.

i) Write the equation for this decomposition of sodium azide.

State symbols are not required.

(1)

ii) In the reaction in (a)(i), a typical airbag is inflated by about 67 dm³ of gas. Calculate the minimum mass of sodium azide, in grams, needed to produce this volume of gas. Use the Ideal Gas Equation and give your answer to an appropriate number of significant figures.

For the purpose of this calculation, assume that the temperature is 300 °C and the pressure is 140000 Pa.

(4)

1.2. The second reaction in the airbag is between the sodium produced in the reaction (a)(i) and potassium nitrate.

$...............Na+...............{KNO}_{3}\rightarrow...............{K}_{2}O+...............{Na}_{2}O+...............{N}_{2}$

Balance the above equation, justifying your answer in terms of the changes in oxidation numbers.

1.3. The third reaction in the airbag is between the metal oxides and silicon dioxide.

State the type of reaction taking place and justify why this reaction is necessary.

1.4. The Maxwell-Boltzmann distribution diagram shows the molecular energies for the gaseous system immediately after the airbag has been deployed.

What is the change in shape of the curve when the airbag cools?