Determination of pH

Materials Required

Procedure

Real Lab Procedure

Determination of pH using pH Paper

  • Take a pH paper strip and place it on a white tile.
  • Pour a drop of the sample on the pH paper using a clean dropper.
  • Observe the colour of the pH paper.
  • Now compare the colour obtained on the pH paper with the different colour shades of the standard colour pH chart and note down the pH value.
  • Similarly, find the pH of the remaining samples using a fresh strip of pH paper and a separate dropper for each sample.

 Determination of pH using Universal Indicator Solution

  • Take a small quantity of the given sample in a test tube using a dropper.
  • Using a dropper pour a few drops of the universal indicator solution into the test tube containing the sample.
  • Shake the test tube well and note the colour developed in the test tube.
  • Now compare the colour produced in the test tube with the different colour shades of the standard colour pH chart and note down the pH value.
  • Similarly, find the pH of the remaining samples.

Simulator Procedure (as performed through the Online Labs)

  • You can select the aqueous solution from the 'Select the aqueous solution' drop down list.
  • Now choose any one of the sample solutions in the beaker by clicking on it.
  • You can find out the pH value of the solution using any of the two methods mentioned below.

Using pH Paper

  • Drag the dropper towards the beaker and dip it into the solution to take the solution in it.
  • Still holding the dropper, move it from the beaker over to the pH paper and release it to pour a few drops of the solution on to the pH paper .
  • The area on the pH paper over which the solution is poured develops a colour.
  • To find the pH value of the solution, select the colour strip from the standard colour pH chart and drag it to the pH paper to compare it.
  • The colour that matches with the spot on the pH paper indicates the pH value of the solution.

Using Universal Indicator Solution

  • Click on the dropper in the universal indicator solution bottle and drag it towards the solution in the beaker to pour the universal indicator into it.
  • The solution changes colour.
  • To find the pH value of the solution, select the colour strip from the standard colour pH chart and drag it near to the solution in the beaker to compare it.
  • The colour that matches with the colour of the solution in the beaker indicates the pH value of the solution.

Observations

Record the observations in a tabular column.

Sample Name For pH Paper For Universal Indicator Solution
Colour produced on the pH Paper Approximate pH Colour produced in the solution Approximate pH
         
         
         

Precautions

  • Use only the standard colour pH chart supplied with the pH paper for assessing the pH value.
  • Keep the pH strips away from chemical fumes.
  • Either use fresh fine dropper or glass rod for each different sample, or wash the dropper or glass rod well with water every time.
  • To correctly view the colour produced on the pH paper, keep the pH paper on a white tile while performing the experiment.

 

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