Acid, Base and Salt

Introduction

Everything around us is made of chemicals. The food we eat, the soap we use, the medicines we take, and even the air we breathe contain various chemical substances. Among these, acids, bases, and salts are some of the most important groups of chemicals. They are found not only in the chemistry lab but also in our kitchen, bathroom, and garden.

Have you ever tasted a lemon and felt its sourness? That sour taste is due to an acid. Have you noticed how soap feels slippery? That is because it is a base. The common salt we sprinkle on our food is a type of salt formed by combining an acid and a base.

In this chapter, we will explore what acids, bases, and salts are, how they behave, and how they react with each other. Understanding these substances helps us connect chemistry to everyday life.

What are Acids?

Acids are chemical substances that have a sour taste. They are commonly found in many food items such as lemon, orange, tamarind, and vinegar. The word "acid" comes from the Latin word acidus, which means sour.

Types of Acids:

1. Natural Acids – These are found naturally in plants and animals.

   • Citric acid in lemons and oranges

   • Lactic acid in curd

   • Tartaric acid in tamarind and grapes

   • Acetic acid in vinegar

2. Mineral Acids – These are strong acids made in laboratories and used in industries.

   • Hydrochloric acid (HCl)

   • Sulfuric acid (H₂SO₄)

   • Nitric acid (HNO₃)

Properties of Acids:

• Taste sour

• Turn blue litmus paper red

• Are corrosive, especially strong acids

• React with metals to release hydrogen gas

• React with bases to form salts and water

• Have a pH value less than 7

Examples:

• Lemon juice (citric acid)

• Vinegar (acetic acid)

• Curd (lactic acid)

• Hydrochloric acid (used in cleaning)

What are Bases?

Bases are chemical substances that have a bitter taste and feel soapy or slippery when touched. They are the opposite of acids. Bases that dissolve in water are called alkalis.

Common Examples of Bases:

• Sodium hydroxide (NaOH) – used in soap making

• Potassium hydroxide (KOH)

• Calcium hydroxide (Ca(OH)₂) – used in whitewashing

• Magnesium hydroxide (Mg(OH)₂) – used in antacids

Properties of Bases:

• Taste bitter

• Feel slippery or soapy

• Turn red litmus paper blue

• React with acids to form salts and water

• Have a pH value greater than 7

Some bases are strong and dangerous. They can burn the skin and must be handled with care. Weak bases, such as those in soap or toothpaste, are safe to use.

What are Salts?

Salts are chemical substances formed when an acid reacts with a base. This reaction is called a neutralization reaction. During this process, the acid and base cancel each other’s properties, forming salt and water.

Neutralization Reaction:

Acid + Base → Salt + Water

Example:
Hydrochloric acid + Sodium hydroxide → Sodium chloride (common salt) + Water

Salts can have many different tastes and colors. Some are edible, while others are used in industries or laboratories.

Common Examples of Salts:

• Sodium chloride (NaCl) – table salt used in food

• Potassium nitrate (KNO₃) – used in fertilizers and fireworks

• Calcium sulfate (CaSO₄) – used to make plaster of Paris

• Ammonium chloride (NH₄Cl) – used in dry cells

Indicators – Detecting Acids and Bases

Indicators are special substances that change color in the presence of an acid or a base. They help us identify whether a given substance is acidic or basic in nature.

Common Indicators:

1. Litmus:

   • Blue litmus turns red in acid

   • Red litmus turns blue in base

2. Turmeric:

   • Yellow in acid

   • Red in base

3. China Rose (Hibiscus):

   • Dark pink in acid

   • Green in base

4. Phenolphthalein:

   • Colorless in acid

   • Pink in base

Indicators are very helpful in experiments and practical science to determine the nature of a substance without tasting or touching it.

Neutralization in Daily Life

Neutralization reactions are not just found in labs. They occur around us every day.

Examples of Neutralization in Real Life:

• Indigestion: Our stomach produces hydrochloric acid to help digest food. Too much acid causes pain or discomfort. Antacids like milk of magnesia (a base) neutralize the extra acid.

• Insect bites: Bee stings are acidic. Rubbing baking soda (a base) helps relieve pain. Wasp stings are basic, and vinegar (an acid) is used to neutralize it.

• Soil treatment: Sometimes, the soil becomes too acidic or too basic. Farmers use slaked lime (a base) to reduce acidity and organic matter to balance soil pH.

• Tooth decay: Bacteria in the mouth produce acid. Toothpaste, which contains mild bases, neutralizes this acid and prevents cavities.

Uses of Acids, Bases, and Salts

Uses of Acids:

• Hydrochloric acid – cleaning bathrooms and toilets

• Sulfuric acid – used in car batteries

• Nitric acid – making fertilizers and explosives

• Acetic acid – used in cooking and food preservation

Uses of Bases:

• Sodium hydroxide – soap and detergent manufacturing

• Magnesium hydroxide – used in antacids for stomach relief

• Calcium hydroxide – whitewashing walls

• Ammonium hydroxide – used in window cleaners

Uses of Salts:

• Sodium chloride – cooking, food preservation

• Calcium sulfate – plaster of Paris, construction

• Potassium nitrate – fertilizers and fireworks

• Zinc sulfate – used in medicines

Safety Tips While Handling Acids and Bases

• Always wear gloves and safety glasses when dealing with chemicals.

• Never taste or smell unknown substances.

• Add acid to water slowly, never the other way around.

• Store acids and bases in properly labeled containers.

• Keep them away from children and pets.

Conclusion

Acids, bases, and salts are essential components of chemistry and daily life. They help us understand how different substances interact and change. Acids are sour and reactive, bases are bitter and slippery, while salts are neutral and formed from acid-base reactions. From digestion to cleaning, from food to farming—these substances are everywhere. Learning about them helps us stay safe and use them wisely in our surroundings. With proper knowledge and safety, we can explore the wonderful world of chemistry all around us.