Changing Concentration

Part of the Energy, Rates and Equilibrium section of Coddy's Chemistry journey. Lesson 28 of 35.

Fe³⁺(aq) + SCN⁻(aq) ⇌ FeSCN²⁺(aq): more SCN⁻ deepens the red (right); less Fe³⁺ fades it (left).

The reaction always moves to use up what was added or replace what was removed.

Adding a solid or a pure liquid does not shift it.

Challenge

A few drops of potassium thiocyanate solution are added to this red mixture at equilibrium:

$\mathrm{Fe^{3+}(aq)} + \mathrm{SCN^-(aq)} \rightleftharpoons \mathrm{FeSCN^{2+}(aq)}$

Which way does the equilibrium shift?

Try it yourself

EquilibriumWhich way does it shift?

Fe³⁺(aq)SCN⁻(aq)FeSCN²⁺(aq)

Test yourself

This lesson includes a short quiz. Start the lesson to answer it and track your progress.

All lessons in Energy, Rates and Equilibrium

1Energy in Reactions

4Rates of Reaction

7Practice Problems

2Bond Energies

5Equilibrium

3Changes of State

6Changing an Equilibrium