Acids, Bases and Salts: Properties, pH Scale & Reactions Explained

Acids, Bases and Salts — Properties, pH Scale & Everyday Examples

Acids and bases are everywhere in your daily life—from the lemon juice in your daal to the soap you use for washing clothes. Understanding their properties helps you understand chemistry, cooking, cleaning, and even your body's health.

In this guide, we'll explore acids, bases, and salts with properties, the pH scale, and real-world examples that matter for CBSE, ICSE, and IB examinations.

What Are Acids?

An acid is a substance that:

• Tastes sour
• Turns blue litmus paper red
• Releases hydrogen ions (H⁺) in solution
• Reacts with metals to produce hydrogen gas
• Reacts with bases to form salts and water

Properties of Acids

1. Sour taste (but never taste lab chemicals!)
2. Turn blue litmus red
3. Conduct electricity (because they contain ions)
4. Corrosive (can damage materials and skin)
5. React with metals: Acid + Metal → Salt + Hydrogen gas

Example: Zn + 2HCl → ZnCl₂ + H₂↑

Common Acids and Examples

Acids in Indian Context

Nimbu (Lemon): Contains citric acid; used in Indian cuisine

Tamarind: Contains tartaric acid; souring agent in chutneys

Buttermilk & Yogurt: Contain lactic acid

Vinegar (Sirka): Acetic acid; used in Indian cooking and preservation

Stomach acid: Hydrochloric acid aids digestion

What Are Bases?

A base is a substance that:

Tastes bitter (never taste lab chemicals!)

Turns red litmus paper blue

Releases hydroxide ions (OH⁻) in solution

Feels slippery

Reacts with acids to form salts and water

Properties of Bases

Bitter taste (but again, don't taste in lab!)

Turn red litmus blue

Conduct electricity (contain ions)

Slippery feeling (don't touch strong bases!)

React with acids: Base + Acid → Salt + Water

Example: 2NaOH + H₂SO₄ → Na₂SO₄ + 2H₂O

Common Bases and Examples

Bases in Indian Context

Chuna (Lime/Calcium hydroxide): Used to whitewash walls, traditionally in betel nut preparations

Chawal ka maal (Rice bran): Slightly basic; used in traditional beauty treatments

Neem leaves: Slightly basic; used in ayurvedic medicine

Wood ash: Contains potassium hydroxide; used in traditional soap making

Baking soda: Used in Indian cooking and cleaning

Alkalis: A Special Type of Base

An alkali is a base that's soluble in water. Not all bases are alkalis—for example, calcium hydroxide is a base, but it's slightly soluble (not a true alkali).

Common alkalis: NaOH, KOH, NH₃ (all dissolve in water)

What Are Salts?

A salt is the product formed when an acid reacts with a base. General reaction: Acid + Base → Salt + Water

Examples of Salts

Properties of Salts

May be acidic, basic, or neutral (depends on acid and base used)

Crystalline solids (usually)

Don't change litmus (neutral salts)

Conduct electricity when dissolved

Various tastes (NaCl is salty, others may be bitter)

Salts in Indian Daily Life

Namak (Salt): Essential in cooking; prevents deficiency disorders

Chuna (Calcium hydroxide): In betel nut mixtures

Alum (Phitkari): Traditional water purification, textile dyeing

Turmeric + salt: Antiseptic for wounds (traditional remedy)

The pH Scale: Measuring Acidity and Basicity

The pH scale measures how acidic or basic a solution is.

CODEBLOCK0

Understanding pH Values

pH = 0-6: Acidic (H⁺ concentration is high)

pH = 7: Neutral (equal H⁺ and OH⁻)

pH = 8-14: Basic/Alkaline (OH⁻ concentration is high)

Formula: pH = -log[H⁺]

Everyday pH Examples

pH in Human Body

Your body maintains very specific pH values:

Blood: pH 7.35-7.45 (slightly basic)

Stomach: pH 1.5-3.5 (very acidic for digestion)

Small intestine: pH 7-8 (slightly basic, to neutralize stomach acid)

Skin: pH 4.5-5.5 (slightly acidic, protective barrier)

Disruption in these pH levels can cause health problems.

Indicators: How to Detect Acids and Bases

Indicators are substances that change color based on pH.

Common Indicators

Natural Indicators from Indian Kitchen

Turmeric: Yellow in acids, brown/black in bases (natural!)

Red cabbage: Color changes dramatically across pH range

Hibiscus flower: Pink in acids, becomes colorless in strong bases

Henna: Changes color with pH

These work surprisingly well for simple pH testing!

Neutralization Reaction

When an acid and base react, they neutralize each other, producing a salt and water.

Equation: Acid + Base → Salt + Water Example: CODEBLOCK1

Real-Life Neutralization Examples

Indigestion: Stomach acid (HCl) is neutralized by antacids like sodium bicarbonate (baking soda)

CODEBLOCK2

Mosquito bites: Bee venom is acidic, ammonia (basic) helps neutralize the sting

Soil amendment: Acidic soil is neutralized with lime (calcium hydroxide) for farming

Lake acidification: Limestone (calcium carbonate) is added to acidic lakes to neutralize them

Types of Salts Based on pH

Not all salts are neutral! Some are acidic or basic:

Neutral Salts

Sodium chloride (NaCl) from HCl + NaOH

Potassium sulfate (K₂SO₄) from H₂SO₄ + KOH

Acidic Salts

Ammonium chloride (NH₄Cl) from HCl + NH₃

Iron(III) chloride (FeCl₃)

Why acidic? The cation (NH₄⁺ or Fe³⁺) hydrolyzes, releasing H⁺ ions.

Basic Salts

Sodium carbonate (Na₂CO₃) from H₂CO₃ + NaOH

Sodium acetate (CH₃COONa) from CH₃COOH + NaOH

Why basic? The anion (CO₃²⁻ or CH₃COO⁻) hydrolyzes, releasing OH⁻ ions.

Quick Recap: Acids vs Bases vs Salts

Try This: Practical Experiments

Make a natural indicator: Boil red cabbage, cut into pieces. The water turns purple. Add drops of acid (lemon juice) or base (baking soda solution) and observe color changes.

Neutralization demo: Add baking soda to vinegar. Observe the fizzing (CO₂ gas) and temperature change.

Test household pH: Using litmus paper or red cabbage indicator, test the pH of lemon juice, milk, soap solution, and water. Record results.

Exam Questions: CBSE/ICSE Pattern

Q1: What is the pH of pure water?

A: pH = 7 (neutral). Equal concentration of H⁺ and OH⁻ ions.

Q2: Write the reaction when an acid reacts with a base.

A: Acid + Base → Salt + Water Example: HCl + NaOH → NaCl + H₂O

Q3: How would you distinguish between an acid and a base using litmus paper?

A: Acids turn blue litmus red. Bases turn red litmus blue.

Q4: Name three natural indicators used to test pH.

A: Red cabbage, turmeric, hibiscus, henna (any three).

Q5: Why is pH control important in agriculture?

A: Different crops grow best at specific pH values. Acidic soil requires lime (calcium hydroxide) to neutralize. Basic soil requires sulfur additions. Maintaining proper pH ensures nutrient availability and crop growth.

FAQ: Acids, Bases and Salts

Q: Is water acidic or basic?

A: Pure water is neutral (pH 7). However, rainwater is slightly acidic (pH ~5.6) because it dissolves CO₂ from the atmosphere, forming weak carbonic acid.

Q: Can a salt be acidic?

A: Yes! Salts formed from weak bases and strong acids are acidic. For example, ammonium chloride (NH₄Cl) is acidic because NH₄⁺ hydrolyzes to release H⁺.

Q: Why do antacids work?

A: They contain bases (like Mg(OH)₂ or Al(OH)₃) that neutralize excess stomach acid (HCl). The neutralization reaction reduces acidity.

Q: What happens if you mix a strong acid with a strong base?

A: They neutralize each other completely, producing a neutral salt and water. If quantities are equal, the resulting solution has pH 7.

Q: Are all bases called alkalis?

A: No. Alkalis are bases that dissolve in water. For example, NaOH is an alkali (soluble base), but Ca(OH)₂ is a base but not a strong alkali (less soluble).

Next Steps

Now that you understand acids, bases, and salts, explore related topics:

Chemical Reactions and Equations – How acids and bases participate in reactions

Periodic Table – How group position predicts acid/base properties

Practice with The Practise Ground chemistry quizzes for more exam-style questions!

Acids and bases are fundamental to chemistry, biology, and everyday life. Understanding them opens doors to understanding medicine, cooking, agriculture, and environmental science. Master this topic, and you'll have a strong foundation for all advanced chemistry.