Question

If anyone could help me answer part B of this problem I would appreciate it.

4. Consider the following reaction used as a rocket fuel:
(CH3)2N2H2 (s) + N2O4 (l) ⇌ 2CO2 (g) + 3N2 (g) + 4H2O (g)
Kp for this reaction is so large you can assume it goes to completion. The gases produced by this reaction were
collected in a closed, 118 L vessel, and at equilibrium, the total pressure was 2.50 atm and the temperature was
400 K.
a) Write the equilibrium constant expression (Kp) for this reaction.
b) What are the partial pressures of CO2, N2, and H2O at equilibrium?

Answer 1

Question #57548, Chemistry, General Chemistry

4. Consider the following reaction used as a rocket fuel:

$$\left(\mathrm{CH_3}\right)_2\mathrm{N_2H_2 (s)} + \mathrm{N_2O_4 (l)} \leftrightarrow 2\mathrm{CO_2 (g)} + 3\mathrm{N_2 (g)} + 4\mathrm{H_2O (g)}$$

$K_p$ for this reaction is so large you can assume it goes to completion. The gases produced by this reaction were collected in a closed, 118 L vessel, and at equilibrium, the total pressure was 2.50 atm and the temperature was 400 K.

a) Write the equilibrium constant expression $(K_p)$ for this reaction.

b) What are the partial pressures of $\mathrm{CO_2, N_2,}$ and $\mathrm{H_2O}$ at equilibrium?

Answer:

a) $K_p = \frac{[\mathrm{CO_2}]^2 \cdot [\mathrm{N_2}]^3 \cdot [\mathrm{H_2O}]^4}{[\mathrm{N_2O_4}]}$

b) $p\mathrm{CO_2} = \frac{2}{9} \cdot 2.5\,\mathrm{atm} = 0.6\,\mathrm{atm}$

$$p\mathrm{N_2} = \frac{1}{9} \cdot 2.5\,\mathrm{atm} = 0.3\,\mathrm{atm}$$ $$p\mathrm{H_2O} = \frac{4}{9} \cdot 2.5\,\mathrm{atm} = 1.1\,\mathrm{atm}$$