Equilibrium constant Kp for homogeneous systems (A-level only) common mistakes

Common mistakes

• Confusing partial pressure with total pressure

  Students often confuse the concept of partial pressure with total pressure, thinking they are the same.

  Fix itRemember that partial pressure refers to the pressure of one specific gas in a mixture, while total pressure is the sum of all partial pressures.

• Incorrectly calculating mole fractions

  Students often forget to sum the total moles before calculating the mole fraction.

  Fix itAlways ensure to calculate the total number of moles in the mixture before finding the mole fraction.

• Incorrectly writing Kp expressions

  Students often forget to raise the partial pressures to the correct stoichiometric coefficients.

  Fix itAlways refer to the balanced equation and ensure that each term in the Kp expression corresponds to the correct power based on the coefficients.

• Incorrect Kp Expression

  Students often forget to raise the partial pressures to the power of their coefficients.

  Fix itAlways ensure that the Kp expression reflects the stoichiometry of the balanced equation.

• Incorrectly writing Kp expressions

  Students often forget to raise the partial pressures to the correct stoichiometric coefficients.

  Fix itAlways ensure that each term in the Kp expression corresponds to the coefficients in the balanced equation.