Acid-Base Reactions and Observations

The video tutorial demonstrates a neutralization reaction using hydrochloric acid, phenolphthalein, and sodium hydroxide. Initially, hydrochloric acid is added to a test tube, followed by phenolphthalein, which does not change the color. Sodium hydroxide is then added drop by drop, turning the solution pink. By adding more hydrochloric acid, the solution becomes colorless again. This activity illustrates how acids and bases can neutralize each other, forming a neutral solution of salt and water. The tutorial emphasizes the concept of neutralization and the chemical changes involved.

What is the purpose of adding phenolphthalein to the test tube in the experiment?

• To neutralize the hydrochloric acid

• To make the solution more alkaline

• To observe color changes during the reaction

• To increase the acidity of the solution

What happens to the color of the solution when sodium hydroxide is added?

• It turns blue

• It remains colorless

• It turns pink

• It turns green

Why is sodium hydroxide added drop by drop to the test tube?

• To dilute the solution

• To increase the volume of the solution

• To prevent the solution from boiling

• To carefully observe the color change

What is the result of adding hydrochloric acid to the pink solution?

• The solution becomes more alkaline

• The solution becomes more acidic

• The solution becomes colorless

• The solution becomes blue

What is the main observation when hydrochloric acid is added to the pink solution?

• The solution turns green

• The solution becomes colorless

• The solution remains pink

• The solution starts boiling

What is the effect of adding excess sodium hydroxide to an acidic solution?

• It becomes neutral

• It remains acidic

• It becomes a base

• It turns into water

What is produced when an acid reacts with a base?

• Gas and water

• Only water

• Salt and water

• Only salt

What happens when acids and bases are mixed in definite proportions?

• They form a neutral solution

• They remain separate

• They explode

• They form a gas