Equilibrium Constants

It's great to know all about equilibria, but it's even better to be able to do some maths with it.

Illustrative background for Equilibrium Constant: K<sub>c</sub>Illustrative background for Equilibrium Constant: K<sub>c</sub> ?? "content

Equilibrium Constant: Kc

  • The equilibrium constant is a constant for a particular reaction at a particular temperature.
    • An equilibrium constant greater than one indicates that the forwards reaction dominates.
    • An equilibrium constant less than one indicates that the backward reaction dominates.
Illustrative background for MathsIllustrative background for Maths ?? "content

Maths

  • For the reaction aA + bB \rightleftharpoons cC + dD:
  • Kc=[D]d[C]c[A]a[B]bK_c = \frac{[D]^d[C]^c}{[A]^a[B]^b}
    • The square brackets indicate concentrations.
    • The indices are the stoichiometries of the components.
      • These are the numbers before each species in the reaction equation - represented above by lower case letters.
Illustrative background for CalculationsIllustrative background for Calculations ?? "content

Calculations

  • We may be given the value of Kc so we will have to sub the values in for each concentration, this will give us a value for Kc.
    • Make sure to sub the units of each concentration into this calculation to make sure the Kc value has the correct units.
  • We can also be given the Kc value and may have to rearrange the equation to find a concentration.

Jump to other topics

1Physical Chemistry

1.1Atoms, Molecules & Stoichiometry

1.2Atomic Structure

1.3Chemical Bonding

1.4States of Matter

1.5Chemical Energetics

1.6Electrochemistry

1.7Equilibria

1.8Partition Coefficient

1.9Reaction Kinetics

2Inorganic Chemistry

3Organic Chemistry & Analysis

3.1Introduction to Organic Chemistry

3.2Hydrocarbons

3.3Halogen Derivatives

3.4Hydroxy Compounds

3.5Carbonyl Compounds

3.6Carboxylic Acids & Derivatives

3.7Nitrogen Compounds

3.8Polymerisation

3.9Analytical Techniques

3.10Organic Synthesis

Unlock your full potential with Seneca Premium

  • Unlimited access to 10,000+ open-ended exam questions

  • Mini-mock exams based on your study history

  • Unlock 800+ premium courses & e-books

Get started with Seneca Premium