How is Kp calculated from partial pressures?

Kp equals the product of partial pressures of products raised to their stoichiometric coefficients divided by the product of partial pressures of reactants raised to their stoichiometric coefficients.

What are the units of Kp?

The units of Kp depend on the stoichiometry of the reaction and may include pressure units raised to various powers, or may have no units.

Why do the units of Kp vary between different equilibria?

The units vary because they depend on the difference between the sum of stoichiometric coefficients of gaseous products and gaseous reactants.

AQA A-Level Chemistry 7405

Atomic Structure

Topic overview Fundamental Particles Mass Number and Isotopes Time of Flight Mass Spectrometry: Ionisation and Acceleration Time of Flight Mass Spectrometry: Drift, Detection and Calculating m/z Electron Configuration: Sub-shells and Orbitals Electron Configuration: Writing Configurations for Atoms and Ions Ionisation Energies and Periodic Trends

Amount of Substance

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Bonding

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Energetics and Thermodynamics

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Kinetics

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Introduction to Organic Chemistry

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Hydrocarbons

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Carbonyls, Carboxylic Acids and Derivatives

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Aromatic Chemistry and Amines

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Polymers, Amino Acids, Proteins and DNA

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Organic Synthesis, NMR and Chromatography

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Chemical Equilibria

The Equilibrium Constant Kp

3 things to know
Papers 1, 2 and 3

Overview

Writing Kp for a gaseous equilibrium, and the effect of temperature and of a catalyst on its value.

What you need to know

Answer each one before you reveal it.

Your recallNot started

Key term

What is the equilibrium constant Kp used for?

Key term

What type of equilibrium systems does Kp apply to?

Key term

In the expression for Kp, what quantity is used instead of concentration?

Questions from this subtopic

Each one with the model answer underneath.

1
What is the equilibrium constant Kp used for?
Model answer
Kp is used to express the equilibrium constant for gaseous equilibria in terms of partial pressures.
2
What type of equilibrium systems does Kp apply to?
Model answer
Kp applies to homogeneous systems involving gases.
3
In the expression for Kp, what quantity is used instead of concentration?
Model answer
Partial pressure is used instead of concentration.
4
How is Kp calculated from partial pressures?
Model answer
Kp equals the product of partial pressures of products raised to their stoichiometric coefficients divided by the product of partial pressures of reactants raised to their stoichiometric coefficients.
5
What are the units of Kp?
Model answer
The units of Kp depend on the stoichiometry of the reaction and may include pressure units raised to various powers, or may have no units.
6
Why do the units of Kp vary between different equilibria?
Model answer
The units vary because they depend on the difference between the sum of stoichiometric coefficients of gaseous products and gaseous reactants.

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