Science Notes for Class 10 Acids Bases-And-Salts

Acids, Bases and Salts

Welcome to the chapter on Acids, Bases and Salts for Class 10. In this chapter, you will learn what acids, bases and salts are, their properties, types, uses, and how they react with other substances. By the end of this chapter, you will be able to identify acids, understand their importance in daily life, and solve problems related to acids in chemistry.

Introduction to Acids

Acids are substances that have a sour taste and turn blue litmus paper red. They are found in many foods and are used in laboratories and industries. Acids play an important role in chemistry and our daily life.

Properties of Acids

Have a sour taste (e.g., lemon juice, vinegar).
Turn blue litmus paper red.
React with metals to produce hydrogen gas.
React with bases to form salt and water (neutralization).
Conduct electricity in aqueous solution.

Types of Acids

Mineral Acids: Made from minerals. Examples: Hydrochloric acid (HCl), Sulphuric acid (H₂SO₄), Nitric acid (HNO₃).
Organic Acids: Found in plants and animals. Examples: Acetic acid (vinegar), Citric acid (lemons), Lactic acid (curd).

Strong and Weak Acids

Strong Acids: Completely ionize in water (e.g., HCl, H₂SO₄).
Weak Acids: Partially ionize in water (e.g., acetic acid, citric acid).

Uses of Acids

Used in car batteries (sulphuric acid).
Used in making fertilizers, medicines, and cleaning agents.
Used in food (citric acid in lemons, acetic acid in vinegar).
Used in laboratories for experiments.

Reactions of Acids

With Metals: Acid + Metal → Salt + Hydrogen gas
With Bases: Acid + Base → Salt + Water (Neutralization)
With Carbonates: Acid + Carbonate → Salt + Water + Carbon dioxide

Safety with Acids

Handle acids with care. They can burn skin and damage eyes.
Always add acid to water, not water to acid.
Wear gloves and safety goggles in the laboratory.

Fun Activity: Test for Acids at Home

Taste a lemon or vinegar (with permission). Notice the sour taste—this is because of the acid present in them!

Introduction to Bases and Salts

Bases and salts are important classes of chemical compounds. Bases are substances that can accept hydrogen ions (protons) or donate a pair of valence electrons. Salts are formed when acids react with bases or metals.

What are Bases?

Base: A substance that tastes bitter, feels soapy, and turns red litmus paper blue.
Bases release hydroxide ions (OH^-) in water.
Examples: Sodium hydroxide (NaOH), potassium hydroxide (KOH), calcium hydroxide (Ca(OH)₂).

Properties of Bases

Bitter taste and slippery feel.
Turn red litmus paper blue.
React with acids to form salt and water (neutralization reaction).
Conduct electricity in aqueous solution.

What are Salts?

Salt: A compound formed when the hydrogen ion (H⁺) of an acid is replaced by a metal ion or ammonium ion.
Salts are usually formed by the reaction of an acid with a base, metal, or carbonate.
Examples: Sodium chloride (NaCl), potassium nitrate (KNO₃), calcium sulfate (CaSO₄).

Formation of Salts

Acid + Base → Salt + Water (Neutralization reaction)
Acid + Metal → Salt + Hydrogen gas
Acid + Carbonate → Salt + Water + Carbon dioxide

Example: HCl + NaOH → NaCl + H₂O

Types of Salts

Normal Salts: Formed by complete replacement of hydrogen ions of an acid by a metal.
Acid Salts: Formed by partial replacement of hydrogen ions.
Basic Salts: Formed by partial replacement of hydroxide ions of a base.

Uses of Bases and Salts

Sodium hydroxide is used in making soap and paper.
Calcium hydroxide is used in whitewashing.
Sodium chloride (common salt) is used in food.
Salts are used in fertilizers, medicines, and industry.

Fun Activity: Test with Litmus Paper

Take a small amount of soap solution and dip red litmus paper in it. What happens? Try the same with salt water. Observe the changes!

Summary

Acids are sour, turn blue litmus red, and react with metals and bases.
There are mineral acids and organic acids.
Acids are used in many industries and in our daily life.
Handle acids safely in the laboratory.
Bases are bitter, soapy, and turn red litmus blue.
Salts are formed by the reaction of acids with bases, metals, or carbonates.
Both bases and salts are useful in daily life and industry.

Practice Questions

Name two properties of acids.
Give two examples of organic acids.
What happens when an acid reacts with a metal?
Why should you handle acids carefully?
What is neutralization?
What is a base? Give two examples.
How is a salt formed?
Write the reaction between hydrochloric acid and sodium hydroxide.
Name two uses of sodium chloride.
What happens when an acid reacts with a carbonate?

Challenge Yourself

List three uses of acids in daily life.
Write the reaction of hydrochloric acid with sodium hydroxide.
Classify the following as acid, base, or salt: NaOH, H₂SO₄, NaCl, Ca(OH)₂, KNO₃.
Explain why common salt is important for our body.

Did You Know?

The acid in your stomach is hydrochloric acid (HCl) and helps in digestion!
Ants inject formic acid when they bite.
Baking soda (sodium bicarbonate) is a salt used in cooking and cleaning.
Some salts can be colored, like copper sulfate (blue) and potassium permanganate (purple).

Glossary

Acid: A substance that tastes sour and turns blue litmus red.
Neutralization: Reaction between an acid and a base to form salt and water.
Litmus: A dye used to test for acids and bases.
Ionize: To split into ions in water.
Base: A substance that releases hydroxide ions in water.
Salt: A compound formed from the reaction of an acid and a base.
Neutralization: A reaction between an acid and a base to form salt and water.
Litmus Paper: A paper strip used to test acids and bases.

Answers to Practice Questions

Sour taste, turn blue litmus red (any two properties).
Citric acid (lemons), acetic acid (vinegar).
It produces salt and hydrogen gas.
Because acids can burn skin and are dangerous if not handled properly.
Neutralization is the reaction between an acid and a base to form salt and water.
A base is a substance that releases hydroxide ions in water. Examples: NaOH, KOH.
A salt is formed when an acid reacts with a base, metal, or carbonate.
HCl + NaOH → NaCl + H₂O
Used in food and as a preservative.
Salt, water, and carbon dioxide are formed.

Explore the world of chemistry by observing Acids, bases and salts around you!

Science Class 10 - Acids Bases-And-Salts Notes