Question

A vessel at 1000 K contains \( \text{CO}_2 \) with a pressure of 0.5 atm. Some of \( \text{CO}_2 \) is converted into \( \text{CO} \) on addition of graphite. If total pressure at equilibrium is 0.8 atm, then \( K_p \) is:

• A. 0.18 atm
• B. 1.8 atm
• C. 0.3 atm
• D. 3 atm

Hint:

To calculate \( K_p \) for a reaction, use the partial pressures of the products and reactants at equilibrium.

Answer 1

The Correct Option is B

The reaction is: \[ \text{CO}_2 (g) + \text{C}(s) \rightleftharpoons 2\text{CO}(g) \] Let \( x \) be the amount of \( \text{CO}_2 \) that dissociates. At equilibrium: Pressure of \( \text{CO}_2 \) = \( 0.5 - x \) atm Pressure of \( \text{CO} \) = \( 2x \) atm Total pressure = \( 0.5 + x = 0.8 \) atm \[ x = 0.3 \, \text{atm} \] Thus: \[ K_p = \frac{(0.6)^2}{0.2} = 1.8 \]