Acids, Bases and Salts

1. State the differences between acids and bases.

Ans:

2. Ammonia is found in many household products such as window cleaners. It turns red litmus blue. What is its nature?

Ans: Ammonia is basic in nature.

3. Name the source from which litmus solution is obtained. What is the use of this solution?

Ans: ∙ Litmus solution is extracted from lichens. ∙ Litmus solution is used as an indicator to find acidic and basic nature of a solution.

4. Is the distilled water acidic/basic/neutral? How would you verify it?

Ans: Distilled water is neutral in nature. This can be tested by using red and blue litmus paper. In either of the cases, the color remains unchanged.

5. Describe the process of neutralization with the help of an example.

Ans: The reaction between an acid and a base is known as neutralization. Salt and water are produced in this process along with the evolution of heat. For example: when sodium hydroxide (NaOH) is added to hydrochloric acid (HCl, sodium chloride (NaCl) and water (H2O) are obtained.

NaOH + HCl → NaCl + H2O + Heat

Antacids like milk of magnesia, baking soda, etc., which contain a base are used for reducing acidity in stomach when excessive acid is released in the stomach.

6. Dorji has a few bottles of soft drink in his restaurant. But, unfortunately, these are not labelled. He has to serve the drinks on the demand of customers. One customer wants acidic drink, another wants basic and third one wants neutral drink. How will Dorji decide which drink is to be served to whom?

Ans: Dorji can taste a few drops of soft drink, if the drink is sour, then it is acidic. If the drink is bitter, then it is basic and neutral drink will not have any taste.

Alternatively, he can use litmus papers to test the nature of soft drink. ∙ If blue litmus paper changes to red, then the drink is acidic in nature. ∙ If red litmus paper changes to blue, then the drink is basic in nature. ∙ If there is no effect on either the blue or red litmus, then the drink is neutral.

7. Explain why: a. An antacid tablet is taken when you suffer from acidity. b. Calamine solution is applied on the skin when an ant bites. c. Factory waste is neutralized before disposing it into the water bodies.

Ans: a. The antacid tablet contains a base like milk of magnesia which neutralizes the acid produced in the stomach. Hence, it is used when one is suffering from acidity.

b. When an ant bites, it injects formic acid into the skin. Calamine consists of zinc carbonate which is basic in nature. Hence, calamine neutralizes the effect of formic acid by giving relief on the affected area.

c. Factory wastes are acidic in nature which may be harmful to the aquatic life. Hence, they are neutralized using a base before disposing them into the water bodies.

8. Three liquids are given to you. One is hydrochloric acid; another is sodium hydroxide and third is a sugar solution. How will you identify them? You have only turmeric indicator.

Ans: a. If the solution is a base, then it would turn turmeric indicator to red; which means it is sodium hydroxide.

b. It the solution is an acid, then it would turn turmeric indicator to yellow; which means it is hydrochloric acid.

c. If the solution is neutral, then it would remain unchanged; which means it is sugar solution.

9. Blue litmus paper is dipped in a solution. It remains blue. What is the nature of the solution? Explain.

Ans: The solution may be neutral or basic in nature as there is no change in the color of blue litmus paper.