Indicators

The video tutorial explains how pH can be measured both quantitatively and qualitatively. It introduces indicators, substances that change color based on the pH of a solution, and discusses various types of indicators such as universal indicator, litmus paper, phenolphthalein, and methyl orange. Each indicator has specific color changes that correspond to different pH levels, which help in determining whether a solution is acidic, neutral, or alkaline. The tutorial concludes by summarizing the role of indicators in pH measurement and their endpoints.

What is the primary function of a pH indicator?

• To measure temperature

• To change the pH of a solution

• To indicate the pH level by changing color

• To measure the volume of a solution

What does a deep red color in a universal indicator signify about the solution's pH?

• The solution is neutral

• The solution is strongly acidic

• The solution is weakly alkaline

• The solution is strongly alkaline

How does blue litmus paper react in an acidic solution?

• It turns green

• It turns red

• It remains unchanged

• It turns blue

At what pH does phenolphthalein change from colorless to pink?

• pH 8.2

• pH 7.0

• pH 4.4

• pH 3.1

What color does methyl orange turn at a pH higher than 4.4?

• Blue

• Yellow

• Green

• Red