Skip to content
MathsGenie logo
Open app

Course home

  1. A Level
  3. Chemistry OCR A
  5. Question bank

Acids, bases and buffers

EasyMediumHard
1234567891011
Question 4

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): Yellow
  • Colour of In−(aq)\text{Colour of In}^-\text{(aq)}Colour of In−(aq): Blue

A few drops of this indicator are added to a solution of 0.10 mol dm-3 sodium hydroxide, causing the solution to turn blue. An excess of 1.0 mol dm-3 hydrochloric acid is then slowly added dropwise with stirring until the acid is in excess.

Which statement describes the colour changes observed in the solution?

The colour changes from blue to green and then to yellow.

The colour changes from yellow to green and then to blue.

The colour changes from blue directly to yellow.

The colour stays blue.

Acids, bases and buffers Questions

  1. A Level
  2. /Chemistry
  3. /Acids, bases and buffers