Question

pH scale is used to compare the acidity of solutions. Find out about pH scale and how it is used. Using pH paper to determine the acidity of different food materials in your home.

Accepted Answer

About pH scale:- pH scale is a numerical scale used in chemistry to determine the acidic, basic and neutral nature of the substance. It has a range between $0 to 14$ . It measures the concentration of hydrogen ions in the solution. If a solution contains a higher concentration of hydrogen ions, it shows lower pH value in pH scale by indicating deep red colour and such solutions are termed as an acidic solution and its range is between 0 to $6.9$ . If a solution contains fewer hydrogen ions, it will show higher pH value in pH scale by indicating deep blue colour and it is termed as a basic solution, its range is between $7.1 to 14$ . Pure water is a neutral and it has pH value $7$ . A change of one unit in pH scale represents the change in the concentration of hydrogen ion by 10 factors, if there is a change in $2$ units in pH scale, the concentration of hydrogen ion is changed by $100$ factors. Thus, a small change in pH scale represents the large change in concentration of hydrogen ions.

Use of pH scale: Litmus paper is dipped into a solution containing base, acid, or neutral substance. Then it is compared with the pH scale. Based on the colour of the litmus paper, solution is differentiated into acidic, basic or neutral and its strength is also determined.

pH scale

Acid range = $0 - 6.9$

Base range = $7.1 - 14 .$

Neutral range = $7 .$

We can use pH paper(litmus paper) by dipping into the food material, if it changes its colour to red, then the food material is acidic. The strength of the acidity depends on the darkness of the red colour. For example, if we dip pH paper in lemon juice, pH paper turns red.

Nivedita Bose and Madhur Gupta Solutions for Chapter: Formative Assignment: Assignment Chapters 6-8, Exercise 1: Formative Assignment: Assignment CHAPTERS 6-8

Nivedita Bose Science Solutions for Exercise - Nivedita Bose and Madhur Gupta Solutions for Chapter: Formative Assignment: Assignment Chapters 6-8, Exercise 1: Formative Assignment: Assignment CHAPTERS 6-8

Questions from Nivedita Bose and Madhur Gupta Solutions for Chapter: Formative Assignment: Assignment Chapters 6-8, Exercise 1: Formative Assignment: Assignment CHAPTERS 6-8 with Hints & Solutions

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