🧪 Class 10 Chemistry — Acids, Bases and Salts FULL MASTER NOTES
CBSE Board 2026 | NCERT Based | Detailed Notes + Equations + PYQs + MCQs + Tricks
📖 INTRODUCTION
Many substances around us are acidic or basic in nature.
- Lemon tastes sour because it contains acid.
- Soap feels slippery because it is basic.
- Toothpaste is basic and helps prevent tooth decay.
- Acids, bases and salts are very important in industries, medicines and daily life.
🌟 ACIDS
Substances that produce hydrogen ions (H⁺ ions) in aqueous solution are called acids.
🌟 Characteristics of Acids
- Sour in taste
- Turn blue litmus red
- Conduct electricity in aqueous solution
- React with metals to produce hydrogen gas
- pH value less than 7
🌟 Examples of Acids
| Acid | Found In |
|---|---|
| Citric acid | Lemon, orange |
| Acetic acid | Vinegar |
| Hydrochloric acid | Stomach |
| Lactic acid | Curd |
| Tartaric acid | Tamarind |
| Formic acid | Ant sting |
🌟 BASES
Substances that produce hydroxide ions (OH⁻ ions) in aqueous solution are called bases.
🌟 Characteristics of Bases
- Bitter in taste
- Soapy or slippery touch
- Turn red litmus blue
- Conduct electricity
- pH value more than 7
🌟 Examples of Bases
| Base | Common Name |
|---|---|
| Sodium hydroxide (NaOH) | Caustic soda |
| Calcium hydroxide [Ca(OH)₂] | Slaked lime |
| Magnesium hydroxide [Mg(OH)₂] | Milk of magnesia |
| Ammonium hydroxide (NH₄OH) | Household cleaner |
🌟 ALKALIS
Bases that dissolve in water are called alkalis.
Examples
- Sodium hydroxide
- Potassium hydroxide
- Ammonium hydroxide
🌟 INDICATORS ⭐ VERY IMPORTANT
Indicators are substances that show different colours in acidic and basic solutions.
🌟 Types of Indicators
| Indicator | In Acid | In Base |
|---|---|---|
| Litmus | Red | Blue |
| Phenolphthalein | Colourless | Pink |
| Methyl orange | Red | Yellow |
🌟 OLFACTORY INDICATORS
Indicators whose smell changes in acidic or basic medium.
Examples
- Onion
- Vanilla
- Clove oil
🌟 NATURAL INDICATORS
| Natural Indicator | Acidic Medium | Basic Medium |
|---|---|---|
| Turmeric | Yellow | Reddish brown |
| China rose | Dark pink | Green |
| Red cabbage | Red | Greenish yellow |
🌟 CHEMICAL PROPERTIES OF ACIDS
🧪 1. Reaction with Metals
Acids react with metals to produce salt and hydrogen gas.
Example
🌟 Observation
- Bubbles of hydrogen gas are formed.
- Hydrogen burns with a pop sound.
🧪 2. Reaction with Metal Carbonates
Acid + Metal Carbonate → Salt + Water + Carbon dioxide
Example
🌟 Observation
Carbon dioxide gas is evolved.
🧪 3. Reaction with Metal Bicarbonates
Acid + Metal Bicarbonate → Salt + Water + Carbon dioxide
Example
🧪 4. Reaction with Bases (Neutralization)
Acid + Base → Salt + Water
Example
🌟 NEUTRALIZATION REACTION ⭐
A reaction in which an acid reacts with a base to form salt and water is called neutralization reaction.
Example
🌟 USES OF NEUTRALIZATION
- Antacids reduce stomach acidity.
- Farmers treat acidic soil using quicklime or slaked lime.
- Factory wastes are neutralized before disposal.
🌟 CHEMICAL PROPERTIES OF BASES
🧪 Reaction with Metals
Bases react with certain metals like zinc and aluminium to produce hydrogen gas.
Example
🌟 IMPORTANT NCERT POINT ⭐
Acids and bases conduct electricity because they produce ions in water.
Dry acids like dry HCl gas do not conduct electricity because ions are absent without water.
🌟 pH SCALE ⭐ VERY IMPORTANT
 |
| Ph scale |
pH scale measures acidity or basicity of a solution.
🌟 pH Range
| pH Value | Nature |
|---|---|
| Less than 7 | Acidic |
| Equal to 7 | Neutral |
| More than 7 | Basic |
🌟 IMPORTANCE OF pH IN DAILY LIFE
1. pH in Digestive System
- Stomach produces hydrochloric acid for digestion.
- Excess acid causes indigestion and pain.
- Antacids neutralize excess acid.
2. Tooth Decay
- Tooth enamel dissolves below pH 5.5.
- Basic toothpaste prevents tooth decay.
3. Self Defence by Animals
- Bee sting contains formic acid.
- Baking soda gives relief because it is basic.
4. Soil pH
Plants require suitable soil pH for healthy growth.
🌟 SALTS
Salts are formed when acids react with bases.
Example
🌟 COMMON SALT
- Chemical name: Sodium chloride
- Formula: NaCl
🌟 Uses of Common Salt
- Food preservation
- Cooking
- Raw material in industries
🌟 CHEMICALS OBTAINED FROM COMMON SALT
- Sodium hydroxide
- Bleaching powder
- Baking soda
- Washing soda
🧪 CHLOR-ALKALI PROCESS ⭐
Process used to obtain sodium hydroxide from brine solution.
Equation
Products Formed
- Sodium hydroxide
- Chlorine gas
- Hydrogen gas
🌟 BLEACHING POWDER
- Chemical formula: CaOCl₂
- Chemical name: Calcium oxychloride
🌟 Preparation
🌟 Uses of Bleaching Powder
- Bleaching cotton and paper
- Disinfecting drinking water
- Used in textile industries
🌟 BAKING SODA
- Chemical name: Sodium hydrogen carbonate
- Formula: NaHCO₃
🌟 Preparation of Baking Soda
🌟 Uses of Baking Soda
- Baking cakes and bread
- Antacid
- Soda-acid fire extinguishers
🌟 WASHING SODA
- Chemical name: Sodium carbonate decahydrate
- Formula: Na₂CO₃·10H₂O
🌟 Preparation
🌟 Uses of Washing Soda
- Cleaning agent
- Removing permanent hardness of water
- Glass and soap industries
🌟 PLASTER OF PARIS (POP)
- Chemical name: Calcium sulphate hemihydrate
- Formula: CaSO₄·½H₂O
🌟 Preparation of POP
🌟 Uses of POP
- Making statues
- Orthopedic plaster
- Decorative materials
- Chalks and toys
🔥 IMPORTANT DIFFERENCES
🌟 Acids vs Bases
| Acids | Bases |
|---|---|
| Sour taste | Bitter taste |
| Turn blue litmus red | Turn red litmus blue |
| pH less than 7 | pH greater than 7 |
| Produce H⁺ ions | Produce OH⁻ ions |
🌟 Baking Soda vs Washing Soda
| Baking Soda | Washing Soda |
|---|---|
| NaHCO₃ | Na₂CO₃·10H₂O |
| Mild base | Stronger base |
| Used in baking | Used in cleaning |
🌟 Strong Acid vs Weak Acid
| Strong Acid | Weak Acid |
|---|---|
| Completely ionized | Partially ionized |
| Example: HCl | Example: Acetic acid |
🎯 MOST IMPORTANT BOARD QUESTIONS WITH ANSWERS
Q1. What is neutralization reaction?
Answer:
A reaction in which an acid reacts with a base to form salt and water is called neutralization reaction.
Example
Q2. Why do acids conduct electricity?
Answer:
Acids conduct electricity because they produce ions in aqueous solution.
Q3. What is pH scale?
Answer:
pH scale is used to measure acidity or basicity of a solution.
Q4. Write uses of baking soda.
Answer:
- Baking cakes and bread
- Antacid
- Fire extinguishers
Q5. What is bleaching powder? Write its uses.
Answer:
Bleaching powder is calcium oxychloride (CaOCl₂).
Uses:
- Disinfecting water
- Bleaching cotton and paper
🧠 SUPER TRICKS
🌟 Indicators Trick
“LiPMo”
- Li → Litmus
- P → Phenolphthalein
- Mo → Methyl orange
🌟 pH Trick
- Acid → Less than 7
- Neutral → 7
- Base → More than 7
🌟 Common Chemicals Trick
“BBWP”
- B → Bleaching powder
- B → Baking soda
- W → Washing soda
- P → POP
✍️ MOST IMPORTANT DIAGRAMS & ACTIVITIES
- pH scale diagram
- Reaction of acid with metal
- Preparation of hydrogen gas
- Chlor-alkali process
- POP preparation
- Litmus test activity
🎯 DEEP STUDY FRIENDLY MCQs ⭐
1. Which ion is produced by acids in water?
A) OH⁻
B) H⁺
C) Cl⁻
D) Na⁺
✅ Answer: B) H⁺
2. Which indicator turns pink in basic solution?
A) Litmus
B) Methyl orange
C) Phenolphthalein
D) Turmeric
✅ Answer: C) Phenolphthalein
3. Tooth decay starts below which pH?
A) 7
B) 6
C) 5.5
D) 8
✅ Answer: C) 5.5
4. Which gas is evolved when acid reacts with metal?
A) Oxygen
B) Hydrogen
C) Nitrogen
D) Carbon dioxide
✅ Answer: B) Hydrogen
5. Formula of baking soda is:
A) Na₂CO₃
B) NaHCO₃
C) CaCO₃
D) NaOH
✅ Answer: B) NaHCO₃
6. Which substance is used in fire extinguishers?
A) Washing soda
B) Baking soda
C) Bleaching powder
D) POP
✅ Answer: B) Baking soda
7. Which process produces sodium hydroxide from brine?
A) Neutralization
B) Chlor-alkali process
C) Distillation
D) Filtration
✅ Answer: B) Chlor-alkali process
8. Which acid is present in vinegar?
A) Citric acid
B) Acetic acid
C) Formic acid
D) Lactic acid
✅ Answer: B) Acetic acid
9. Which salt removes hardness of water?
A) POP
B) Baking soda
C) Washing soda
D) Bleaching powder
✅ Answer: C) Washing soda
10. POP is used for:
A) Cooking
B) Making statues
C) Toothpaste
D) Fertilizers
✅ Answer: B) Making statues
🔥 IMPORTANT NCERT POINTS
- Acids and bases produce ions only in water.
- pH below 7 is acidic.
- Tooth decay begins below pH 5.5.
- Common salt is an important industrial chemical.
- Baking soda is used in fire extinguishers.
- POP is used in orthopedic casts.
🎯 EXPECTED BOARD QUESTIONS 2026
- Explain neutralization reaction with equation.
- Define pH scale and explain its importance.
- Differentiate between acids and bases.
- Explain chloro-alkali process.
- Write preparation and uses of bleaching powder.
- Explain uses of baking soda and washing soda.
- What are indicators? Explain different types.
- Explain importance of pH in daily life.
