An aqueous equilibrium mixture containing chromate and dichromate ions is represented by the equation:
2CrO42−(aq) [yellow]+2H+(aq)⇌Cr2O72−(aq) [orange]+H2O(l) 2\text{CrO}_4^{2-}(\text{aq}) \text{ [yellow]} + 2\text{H}^+(\text{aq}) \rightleftharpoons \text{Cr}_2\text{O}_7^{2-}(\text{aq}) \text{ [orange]} + \text{H}_2\text{O}(\text{l}) 2CrO42−(aq) [yellow]+2H+(aq)⇌Cr2O72−(aq) [orange]+H2O(l)A student adds a few drops of concentrated sodium hydroxide, NaOH(aq)\text{NaOH}(\text{aq})NaOH(aq), to the orange mixture at equilibrium.
What is the observed colour change?
The mixture turns yellow.
The mixture becomes a deeper orange.
The mixture turns green.
The mixture becomes colourless.
Practise Edexcel GCSE Chemistry Reversible reactions and equilibria with exam-style questions for Foundation and Higher tier. 38 questions, matched to the Edexcel GCSE Chemistry (1CH0) specification and written in Paper 1 and Paper 2 style. Every question includes a full worked solution and mark scheme, so you can see where marks are awarded rather than just whether you got the answer right.
