Indicator in chemistry

In chemistry, an indicator is a material that is used to notice or find the

• Presence
• Absence
• or concentration of another substance, usually in a solution.

How indicator work?

When indicators come into touch with the chemical they are intended to detect, they experience a noticeable change, such as a colour shift.

 

Examples:

 

A few examples of indicator is given below:

Phenolphthalein:

Bromothymol blue:

Methyl orange:

Eriochrome Black T:

Silver nitrate:

Phenolphthalein:

This is an acid-base indicator that is usually utilized in titrations to find the endpoint of an acid-base reaction.

• Phenolphthalein is colorless in acidic solutions
• but turns pink in basic solutions.

Bromothymol blue:

It is called an acid-base indicator and  is commonly used in chemistry.

• It is blue in basic solutions and yellow in acidic solutions.

Methyl orange:

It is an acid-base indicator and is commonly used in titrations.

• It is red in acidic solutions and yellow in basic solutions.

Eriochrome Black T:

This is also known as complexometric indicator and is commonly used to determine the endpoint of titrations involving metal ions.

• It is blue in the presence of metal ions and red in the absence of metal ions.

Silver nitrate:

This is a precipitation indicator that is usually used to trace out the presence of chloride ions. When silver nitrate is mixed with a solution containing chloride ions, a white precipitates of silver chloride is formed.