Writing K

Part of the Energy, Rates and Equilibrium section of Coddy's Chemistry journey. Lesson 24 of 35.

Three steps: balanced equation; products over reactants; coefficients as powers.

Ions too:

$K = \frac{[\mathrm{FeSCN^{2+}}]}{[\mathrm{Fe^{3+}}][\mathrm{SCN^-}]}$

Equation reversed: K upside down.

Challenge

Iron(III) ions are tested for with thiocyanate ions, which form a blood-red complex. Build K for Fe³⁺(aq) + SCN⁻(aq) ⇌ FeSCN²⁺(aq).

Try it yourself

EquilibriumWrite the equilibrium expression

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