Question

Activity 4.7
Compare the pH of dilute acetic acid
and dilute hydrochloric acid using
both litmus paper and universal
indicator.
Are both acids indicated by the
litmus test?
Does the universal indicator show them as equally strong acids?​

Answer 1

Explanation:

To compare the pH of solutions of strong and weak acids of the same concentration – hydrochloric acid (HCl) and acetic acid (CH3COOH).

Materials Required:

0.1M HCl, 0.01M HCl, 0.001M HCl, 0.0001 M HCl, and 0.00001M HCl test tubes, glass rod, and universal indicator.

The procedure of determining the pH using pH paper:-

Take 2-3 drops of solutions of the given concentration on pH paper with the help of glass rod.

Observe the change in colour of the pH paper

Match the shade of the pH paper with standard pH indicator chart.

Note the approximate pH of the sample

The procedure of determining the pH using universal indicator:

Take dry 5 test tubes and fill 5 mL of each solution of various concentration given using measuring cylinder.

Drop 2-3 drops of universal indicator in each test tube using a dropper.

Note the change in the colour seen in the test tube.

Compare the colour of the solution in the test tube with a standard pH indicator chart

note the pH of the solution

Precautions to be taken during the experiment:

Ensure to handle the test tube carefully.

Do not add more indicator.

Keep the pH paper clean.

Compare the colour of the solution in the test tube and pH paper colour exactly with the standard pH indicator chart.

Observation

sample The colour produced on pH paper The colour produced in solution Approximate pH value Comparing the pH of solutions of strong and weak acids-observation

0.1M HCl

0.01M HCl

0.001M HCl

0.0001M HCl

0.00001M HCl Swipe left

Viva Voice:

What is the effect of dilution on pH?

the pH of the acidic solution increases on dilution

the pH of basic solution decreases on dilution

What is the universal indicator?Universal indicator is a mix of several indicators having various pH range. It is used to highlight the colour range due to change in pH.

What is the pH of the acidic solution?Less than 7

What is the pH indicator chart?It is a standard chart that displays the resultant colour with corresponding pH value.

What is an acid-base indicator?It is an inorganic indicator that indicates the change in colour with the change in pH value.

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