Question

Dichromate(VI) ions are orange in colour while chromate(VI) ions are yellow. Consider the following equilibrium.
Cr₂O₇²⁻(aq) + 2OH⁻(aq)  2CrO₄²−(aq) + H₂O(l)
State and explain the observation that will be made if sulphuric(VI) acid is added to the mixture. 

Answer 1

1. Intensity of orange colour increases 
2. Addition of H⁺ removes OH⁻ hence reverse/backward reaction is favoured / equilibrium shifts to the left.