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Rates, equilibrium and pH

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Question 23

The equilibrium equation for an indicator, HIn\text{HIn}HIn, is shown below.

HIn(aq)⇌In−(aq)+H+(aq) \text{HIn(aq)} \rightleftharpoons \text{In}^-\text{(aq)} + \text{H}^+\text{(aq)} HIn(aq)⇌In−(aq)+H+(aq)
  • Colour of HIn(aq)\text{Colour of HIn(aq)}Colour of HIn(aq): Red
  • Colour of In−(aq)\text{Colour of In}^-\text{(aq)}Colour of In−(aq): Yellow

The indicator is added to an acidic solution, causing the solution to turn red. An excess of aqueous sodium hydroxide is then added.

Which statement describes how the colour of this solution would be expected to change?

Colour changes from red to yellow.

Colour changes from red to orange.

Colour changes from red to orange and then to yellow.

Colour stays red.

Rates, equilibrium and pH Questions

  1. A Level
  2. /Chemistry
  3. /Rates, equilibrium and pH