Equilibrium Constant Calculations

Kp and Kc Relationship

The relationship between $ K_p $ (the equilibrium constant in terms of partial pressures) and $ K_c $ (the equilibrium constant in terms of concentrations) is given by:

$$ K_p = K_c(RT)^{\Delta n} $$

where:

• $ K_p $ is the equilibrium constant expressed in terms of partial pressures.
• $ K_c $ is the equilibrium constant expressed in terms of molar concentrations.
• $ R $ is the ideal gas constant ( $ 0.0821 \frac{L \cdot atm}{mol \cdot K} $ ).
• $ T $ is the temperature in Kelvin.
• $ \Delta n $ is the change in the number of moles of gas in the balanced chemical equation (moles of gaseous products - moles of gaseous reactants).

Important Considerations:

• This equation only applies to reactions involving gases.
• $ \Delta n $ only considers gaseous species. Liquids and solids are excluded.
• Units are crucial: Ensure consistent units throughout the calculation.

Examples:

• **For a reaction where $ \Delta n = 0 $ **: $ K_p = K_c $ . The equilibrium constants are numerically equal.

• **For a reaction where $ \Delta n > 0 $ **: $ K_p > K_c $ . More gaseous products than reactants.

• **For a reaction where $ \Delta n < 0 $ **: $ K_p < K_c $ . More gaseous reactants than products.

Ideal Gas Law (This note will explain the Ideal Gas Law and its relevance to the Kp and Kc relationship)

Equilibrium Constants (This note will cover a more general overview of equilibrium constants including Kc and other types)

Chemical Equilibrium (This note will provide a foundational understanding of chemical equilibrium and the factors that influence it)