Acids, Bases and Salts
Subject: Science (Chemistry) | Topic: Acids, Bases and Salts
For TLT, ECT, PST, JEST & All Competitive Exams
In our last topic, we studied Chemical Bonding — how atoms combine to form compounds through ionic and covalent bonds. Now we look at one of the most common and practical results of these bonds: Acids, Bases, and Salts. These substances are found everywhere around us, from the food we eat to the cleaning products we use, and this topic is a favorite area for MCQs in TLT, ECT, PST, and JEST exams.
What is an Acid?
An acid is a substance that releases Hydrogen ions (H⁺) when dissolved in water. Acids taste sour, turn blue litmus paper red, and react with metals to produce hydrogen gas.
Examples: Lemon juice (citric acid), vinegar (acetic acid), hydrochloric acid (HCl) found in the stomach, sulfuric acid (H₂SO₄).
What is a Base?
A base is a substance that releases Hydroxide ions (OH⁻) when dissolved in water. Bases taste bitter, feel soapy or slippery to touch, and turn red litmus paper blue.
Examples: Soap, baking soda (sodium bicarbonate), ammonia solution, sodium hydroxide (NaOH), milk of magnesia.
Litmus Test for Acids and Bases
The pH Scale
The pH scale measures how acidic or basic a substance is, ranging from 0 to 14. A pH less than 7 indicates an acid, a pH of exactly 7 is neutral, and a pH greater than 7 indicates a base.
| pH Value | Nature | Example |
|---|---|---|
| 0 – 6 | Acidic | Lemon juice (2), Vinegar (3), Stomach acid (1-2) |
| 7 | Neutral | Pure Water |
| 8 – 14 | Basic (Alkaline) | Baking soda (9), Soap (10), Ammonia (11) |
What is a Salt?
A salt is a compound formed when an acid reacts with a base in a neutralization reaction. This reaction also produces water. Salts are usually neutral in nature (pH close to 7), though some salts can be slightly acidic or basic.
Example: HCl + NaOH → NaCl + H₂O
Key Differences Between Acids and Bases
| Basis | Acid | Base |
|---|---|---|
| Ion Released | Hydrogen ion (H⁺) | Hydroxide ion (OH⁻) |
| Taste | Sour | Bitter |
| Touch | No specific feel | Soapy / Slippery |
| Litmus Test | Turns blue litmus red | Turns red litmus blue |
| pH Value | Less than 7 | Greater than 7 |
| Example | Lemon juice, Vinegar, HCl | Soap, Baking soda, NaOH |
Why This Topic Matters
Acids, Bases, and Salts appear in daily life — from digestion to cleaning products to soil chemistry in agriculture. Understanding the pH scale and neutralization reactions connects directly to Chemical Bonding and prepares students for later topics on chemical reactions. This makes it a consistently repeated topic in TLT, ECT, PST, and JEST exams.
Practice MCQs
1. Which ion is released by an acid when dissolved in water?
a) OH⁻ b) H⁺ c) Na⁺ d) Cl⁻
2. What is the pH value of pure water?
a) 0 b) 7 c) 14 d) 10
3. Which of the following turns red litmus paper blue?
a) Lemon juice b) Vinegar c) Baking soda d) Hydrochloric acid
4. What is produced along with a salt in a neutralization reaction?
a) Oxygen b) Water c) Carbon dioxide d) Hydrogen gas
5. Which of the following has a pH value greater than 7?
a) Lemon juice b) Vinegar c) Soap d) Stomach acid
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