1.10 - Kp, Equilibrium constant

• What is the definition of partial pressure?

  Pressure a gas would have alone in volume
• How do you calculate total pressure in a mixture of gases?

  Total pressure equals the sum of partial pressures
• What is the formula for total pressure in a mixture of three gases?

  P = p1 + p2 + p3
• How is partial pressure calculated using mole fraction?

  Partial pressure = mole fraction x total pressure
• What is the formula for mole fraction?

  Mole fraction = number of moles of gas / total moles
• Given 0.2 moles N2, 0.5 moles O2, and 1.2 moles CO2, what is the total moles of gas?

  Total moles = 1.9
• What is the mole fraction of N2 in the mixture?

  Mole fraction of N2 = 0.105
• Calculate the partial pressure of O2 if total pressure is 3 kPa.

  Partial pressure of O2 = 0.789
• What is the partial pressure of CO2 in the mixture?

  Partial pressure of CO2 = 1.896
• What is the unit of Kp?

  kPa$-2$
• What happens to Kp if the equation is reversed?

  Kp will be the inverse of the original
• What does Kp expression include?

  Only gases, ignore solids and liquids
• If 20% of N2 reacts, how many moles of N2 reacted?

  0.2 moles of N2 reacted
• How many moles of H2 reacted if 0.2 moles of N2 reacted?

  0.6 moles of H2 reacted
• What are the equilibrium moles of NH3 formed if 0.2 moles of N2 reacted?

  0.4 moles of NH3 formed
• What is the mole fraction of NH3 at equilibrium?

  Mole fraction of NH3 = 0.111
• Calculate the partial pressure of NH3 at equilibrium if total pressure is 2 kPa.

  Partial pressure of NH3 = 0.222
• What is the relationship between Kp and the amount of products?

  • Larger Kp indicates more products
  • Smaller Kp indicates favored reactants
• How do temperature changes affect Kp?

  • Kp changes with temperature
  • Kp remains constant with pressure changes
  • Kp remains constant with concentration changes
• How does pressure affect the position of equilibrium?

  • Increased pressure shifts equilibrium to fewer moles
  • Kp value remains unchanged
• What is the Kp expression for the reaction N2 + 3H2 ⇌ 2NH3?

  Kp = $\frac{p(NH3)^2}{p(N2) \cdot p(H2)^3}$
• What is the effect of increasing temperature on an exothermic reaction's equilibrium?

  Equilibrium shifts left, Kp decreases
• What happens to the equilibrium position when pressure is increased in a reaction with fewer moles of gas on the product side?

  Equilibrium shifts right, Kp remains constant
• What is the formula for Kp when using mole fractions?

  Kp = $\frac{x(NH3)^2 \cdot P^2}{x(N2) \cdot x(H2)^3 \cdot P^4}$
• What does Kp expression exclude?

  Excludes solids and liquids
• What is the significance of writing an equation when quoting Kp values?

  It clarifies the direction of the reaction
• How does a catalyst affect Kc or Kp?

  Catalyst has no effect on Kc or Kp
• What is the effect of changing conditions on Kc or Kp?

  Kc and Kp only change with temperature
• What is the relationship between Kp and the amount of products at equilibrium?

  Larger Kp indicates greater product amount