1.1. Hydrazine, N₂H₄, is an oily liquid that vaporises easily.

Calculate the volume, in cm³, that 2.00g of hydrazine occupies at 225 ^°C and 100 kPa.

The gas constant, R = 8.31 J K^–1 mol^–1

Give your answer to 3 significant figures.

1.2. Hydrazine decomposes on heating into a mixture of nitrogen and hydrogen:

N₂H₄ (g) $\rightleftharpoons$ N₂ (g) + 2H₂ (g)

A sample of hydrazine was heated and allowed to reach equilibrium at a given temperature.

The equilibrium mixture contained 5.75 g of nitrogen.

Calculate the mass, in g, of hydrogen gas in the equilibrium mixture.

1.3. A different mass of hydrazine was heated and allowed to reach equilibrium at 950 K.

N₂H₄ (g) $\rightleftharpoons$ N₂ (g) + 2H₂ (g)

The amounts of each substance in the equilibrium mixture are shown in Table 1.

Table 1

For this reaction at 950 K, the equilibrium constant, K_p = 4.31 x 10⁹ Pa²

Calculate the mole fraction of each substance at equilibrium.

Give the expression for the equilibrium constant, K_p

Calculate the total pressure, in Pa, of this equilibrium mixture.

1.4. For this reaction at 950 K, the equilibrium constant, K_p = 4.31 x 10⁹ Pa²

For this reaction at 500 K, the equilibrium constant, K_p = 3.34 x 10⁶ Pa²

Explain how this information can be used to deduce that the forward reaction is endothermic.

1.5. Use the data in part d) to calculate the value of K_p for this reaction

2N₂H₄ (g) $\rightleftharpoons$ 2N₂ (g) + 4H₂ (g)

Deduce the units of K_p.