Three solutions are given:

• A = ACIDIC
• B = Basic
• C = Nuetral

How can we identify the type of solution?

There are two possible methods:

• By using some indicators like litmus paper, phenolphthalein, etc.
• By using Universal Indicators.

Method 1:

Litmus Paper:

Acidic:

⇒When red litmus paper is added in sample solution A, we can observe no colour change.

⇒When blue litmus paper is added in sample solution A, we can observe that the colour CHANGES to red.

⇒From this, we can say that solution A is acidic.

• Red litmus solution: No colour change.

• Blue limus solution: Red

Basic:

⇒When red litmus paper is added in sample solution B, we can observe that the colour changes to blue.

⇒When blue litmus paper is added in sample solution B, we can observe no colour change.

⇒From this, we can say that solution B is basic.

• Red litmus solution: Blue

• Blue limus solution: No colour change.

Nuetral:

⇒When red and blue litmus paper is added in sample solution C, we can observe no colour change.

⇒From this, we can say that solution C is neutral.

Phenolphthalein:

Acidic:

⇒When Phenolphthalein is added in sample solution A, the solution becomes colourless.

From this, we can say that solution A is acidic.

Basic:

⇒When Phenolphthalein is added in sample solution B, then the colour of the solution becomes pink.

From this, we can say that solution B is basic.

Nuetral:

⇒ When Phenolphthalein is added in sample solution C, then the colour of the solution becomes colourless.

From this, we can say that solution C is neutral.

Like this the type of solution can be identified by using various indicators. By observing change in colour of the solution, we can identify whether the solution is acidic, basic or neutral in nature.

Method 2:

Universal indicators:

⇒From universal indicators, we can check the pH value of a solution.

⇒This method is more efficient because we can identify whether a solution is strongly acidic/basic or weakly acidic/basic in nature.

Know some pH values:

• Strong Acid = 0-3
• Weak Acid = More than 3 to less than 7
• Weak BASE = 7-10
• Strong Base = More than 10 and less than 14