# Acid, Base and Salt - Grade 10 (SEE) Chemistry
## Complete Chapter Notes with All Exercises - NEB Curriculum 2080

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## 🎯 Chapter Overview
**Class 10 Science Complete Notes on Acid, Base and Salt chapter** are comprehensively prepared to include **all the exercises given in Acid, Base and Salt chapter of science book such as question answer, numericals, give reason, diagrammatic questions and define the following.** This note is published for helping students to solve their problems and master this fundamental chemistry chapter.

**Weightage:** 15-18 marks in SEE examination
**Time Required:** 30-35 periods

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## 📚 Learning Objectives
After studying this chapter, students will be able to:
- Define acids, bases, and salts with their properties
- Understand pH scale and indicators
- Explain neutralization reactions and salt formation
- Apply knowledge of acids and bases in daily life
- Solve numerical problems related to pH calculations
- Identify different types of salts and their preparation

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## 🍋 1. ACIDS

### 1.1 Definition
**An acid is a substance that tastes sour, turns blue litmus red, and releases hydrogen ions (H⁺) when dissolved in water.**

### 1.2 Properties of Acids
**Physical Properties:**
- Sour taste (like lemon, vinegar)
- Conduct electricity in aqueous solution
- Turn blue litmus paper red
- pH value less than 7

**Chemical Properties:**

#### 1. Reaction with Metals
**Acid + Metal → Salt + Hydrogen gas**
```
2HCl + Zn → ZnCl₂ + H₂↑
H₂SO₄ + Mg → MgSO₄ + H₂↑
```

#### 2. Reaction with Metal Oxides (Bases)
**Acid + Metal Oxide → Salt + Water**
```
H₂SO₄ + CuO → CuSO₄ + H₂O
2HCl + MgO → MgCl₂ + H₂O
```

#### 3. Reaction with Metal Carbonates
**Acid + Metal Carbonate → Salt + Water + CO₂**
```
2HCl + CaCO₃ → CaCl₂ + H₂O + CO₂↑
H₂SO₄ + Na₂CO₃ → Na₂SO₄ + H₂O + CO₂↑
```

#### 4. Reaction with Metal Hydrogen Carbonates
**Acid + Metal Bicarbonate → Salt + Water + CO₂**
```
HCl + NaHCO₃ → NaCl + H₂O + CO₂↑
```

### 1.3 Types of Acids

#### Strong Acids
- Completely ionize in water
- Examples: HCl, H₂SO₄, HNO₃
- pH: 0-3

#### Weak Acids
- Partially ionize in water
- Examples: CH₃COOH, H₂CO₃
- pH: 3-6

### 1.4 Common Acids and Uses
- **Hydrochloric Acid (HCl):** Stomach acid, cleaning
- **Sulfuric Acid (H₂SO₄):** Car batteries, fertilizers
- **Nitric Acid (HNO₃):** Explosives, fertilizers
- **Acetic Acid (CH₃COOH):** Vinegar, food preservation

---

## 🧼 2. BASES

### 2.1 Definition
**A base is a substance that tastes bitter, turns red litmus blue, and releases hydroxide ions (OH⁻) when dissolved in water.**

### 2.2 Properties of Bases
**Physical Properties:**
- Bitter taste
- Slippery/soapy feel
- Conduct electricity in solution
- Turn red litmus paper blue
- pH value greater than 7

**Chemical Properties:**

#### 1. Reaction with Acids (Neutralization)
**Base + Acid → Salt + Water**
```
NaOH + HCl → NaCl + H₂O
Ca(OH)₂ + H₂SO₄ → CaSO₄ + 2H₂O
```

#### 2. Reaction with Metals
**Base + Metal → Salt + Hydrogen**
```
2NaOH + Zn → Na₂ZnO₂ + H₂↑
```

#### 3. Reaction with Non-metal Oxides
**Base + Non-metal Oxide → Salt + Water**
```
2NaOH + CO₂ → Na₂CO₃ + H₂O
```

### 2.3 Types of Bases

#### Strong Bases
- Completely ionize in water
- Examples: NaOH, KOH, Ca(OH)₂
- pH: 11-14

#### Weak Bases
- Partially ionize in water
- Examples: NH₄OH, Mg(OH)₂
- pH: 8-10

### 2.4 Alkalis
**Water-soluble bases are called alkalis.**
- Examples: NaOH, KOH, NH₄OH
- All alkalis are bases, but all bases are not alkalis

### 2.5 Common Bases and Uses
- **Sodium Hydroxide (NaOH):** Soap making, paper industry
- **Calcium Hydroxide [Ca(OH)₂]:** Whitewashing, antacid
- **Magnesium Hydroxide [Mg(OH)₂]:** Antacid, laxative
- **Ammonia (NH₃):** Fertilizers, cleaning agents

---

## 🌈 3. INDICATORS

### 3.1 Definition
**Indicators are substances that show different colors in acidic and basic solutions.**

### 3.2 Types of Indicators

#### Natural Indicators
- **Litmus:** From lichens
- **Red cabbage:** Purple in neutral, red in acid, green in base
- **Turmeric:** Yellow in neutral, red in base

#### Synthetic Indicators
- **Methyl Orange:** Red in acid, yellow in base
- **Phenolphthalein:** Colorless in acid, pink in base

### 3.3 Universal Indicator
- Shows different colors for different pH values
- Provides more accurate pH measurement
- Color range: Red (pH 1) to Purple (pH 14)

### 3.4 Indicator Color Chart

| Indicator | Acidic Solution | Basic Solution | Neutral Solution |
|-----------|-----------------|----------------|------------------|
| Litmus | Red | Blue | Purple |
| Methyl Orange | Red | Yellow | Orange |
| Phenolphthalein | Colorless | Pink | Colorless |

---

## ⚖️ 4. pH SCALE

### 4.1 Definition
**pH is a scale to measure the hydrogen ion concentration in a solution. It ranges from 0 to 14.**

pH = -log[H⁺]

### 4.2 pH Scale Values
- **pH < 7:** Acidic solution
- **pH = 7:** Neutral solution  
- **pH > 7:** Basic solution

### 4.3 pH of Common Substances
- **Battery acid:** pH 0-1
- **Lemon juice:** pH 2
- **Coffee:** pH 5
- **Pure water:** pH 7
- **Soap:** pH 9
- **Household ammonia:** pH 11

### 4.4 Importance of pH
- **Human blood:** pH 7.4 (must be maintained)
- **Soil pH:** Affects plant growth
- **Digestive system:** Stomach (pH 1-2), Small intestine (pH 8)
- **Tooth decay:** Occurs when mouth pH < 5.5

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## 🧂 5. SALTS

### 5.1 Definition
**A salt is formed when hydrogen ions of an acid are replaced by metal ions or ammonium ions.**

### 5.2 Formation of Salt
**General reaction:** Acid + Base → Salt + Water

### 5.3 Types of Salts

#### A. Normal Salt (Neutral Salt)
- **pH = 7**
- Formed by complete neutralization of strong acid and strong base
- **Examples:** NaCl, KCl, Na₂SO₄
- **Formation:** HCl + NaOH → NaCl + H₂O

#### B. Acidic Salt
- **pH < 7**
- Formed when strong acid reacts with weak base
- **Examples:** NH₄Cl, (NH₄)₂SO₄
- **Formation:** HCl + NH₄OH → NH₄Cl + H₂O

#### C. Basic Salt
- **pH > 7**
- Formed when weak acid reacts with strong base
- **Examples:** Na₂CO₃, CH₃COONa
- **Formation:** 2NaOH + H₂CO₃ → Na₂CO₃ + 2H₂O

#### D. Acid Salt
- Contains replaceable hydrogen atoms
- **Examples:** NaHSO₄, KHCO₃
- **Formation:** H₂SO₄ + NaOH → NaHSO₄ + H₂O

### 5.4 Preparation of Salts

#### Method 1: Acid + Base (Neutralization)
```
HCl + NaOH → NaCl + H₂O
H₂SO₄ + 2KOH → K₂SO₄ + 2H₂O
```

#### Method 2: Acid + Metal
```
2HCl + Zn → ZnCl₂ + H₂↑
H₂SO₄ + Fe → FeSO₄ + H₂↑
```

#### Method 3: Acid + Metal Oxide
```
2HCl + CuO → CuCl₂ + H₂O
H₂SO₄ + ZnO → ZnSO₄ + H₂O
```

#### Method 4: Acid + Metal Carbonate
```
2HCl + CaCO₃ → CaCl₂ + H₂O + CO₂↑
```

#### Method 5: Double Displacement
```
AgNO₃ + HCl → AgCl↓ + HNO₃
BaCl₂ + H₂SO₄ → BaSO₄↓ + 2HCl
```

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## 💊 6. IMPORTANT SALTS IN DAILY LIFE

### 6.1 Sodium Chloride (NaCl) - Common Salt
**Preparation:** Solar evaporation of seawater
**Uses:**
- Food seasoning and preservation
- Manufacturing chemicals
- De-icing roads

### 6.2 Sodium Hydroxide (NaOH) - Caustic Soda
**Preparation:** Chlor-alkali process
**Uses:**
- Soap and detergent manufacturing
- Paper industry
- Petroleum refining

### 6.3 Sodium Carbonate (Na₂CO₃·10H₂O) - Washing Soda
**Preparation:** Solvay process
**Uses:**
- Glass manufacturing
- Water softening
- Cleaning agent

### 6.4 Sodium Hydrogen Carbonate (NaHCO₃) - Baking Soda
**Preparation:** From sodium carbonate and CO₂
**Uses:**
- Baking (releases CO₂)
- Antacid
- Fire extinguisher

### 6.5 Calcium Oxide (CaO) - Quick Lime
**Preparation:** Heating limestone
**Uses:**
- Steel manufacturing
- Cement production
- Water treatment

### 6.6 Calcium Hydroxide [Ca(OH)₂] - Slaked Lime
**Preparation:** CaO + H₂O → Ca(OH)₂
**Uses:**
- Whitewashing
- Manufacturing bleaching powder
- Sugar refining

### 6.7 Calcium Sulfate (CaSO₄·½H₂O) - Plaster of Paris
**Preparation:** Heating gypsum
**Uses:**
- Making plaster casts
- Decorative materials
- Fixing bone fractures

### 6.8 Calcium Chloride Hypochlorite (CaOCl₂) - Bleaching Powder
**Preparation:** Ca(OH)₂ + Cl₂ → CaOCl₂ + H₂O
**Uses:**
- Bleaching fabrics
- Disinfectant
- Water treatment

---

## 📋 7. COMPLETE EXERCISE SOLUTIONS

### **1. Choose the correct options:**

**a. Which acid is present in vinegar?**
(i) Lactic acid (ii) Acetic acid ✓ (iii) Tartaric acid (iv) Oxalic acid

**Answer:** (ii) Acetic acid

**b. The pH of pure water is:**
(i) 6 (ii) 7 ✓ (iii) 8 (iv) 9

**Answer:** (ii) 7

**c. Which gas is evolved when metal reacts with acid?**
(i) CO₂ (ii) O₂ (iii) H₂ ✓ (iv) N₂

**Answer:** (iii) H₂

**d. The chemical name of baking soda is:**
(i) Sodium carbonate (ii) Sodium hydrogen carbonate ✓ (iii) Sodium chloride (iv) Sodium hydroxide

**Answer:** (ii) Sodium hydrogen carbonate

### **2. Answer the following questions:**

**a. Define acid with two examples.**

**Answer:** An acid is a substance that tastes sour, turns blue litmus red, and releases H⁺ ions in water.
**Examples:** Hydrochloric acid (HCl), Sulfuric acid (H₂SO₄)

**b. What is the difference between acid and base?**

**Answer:**
| Acid | Base |
|------|------|
| Sour taste | Bitter taste |
| Turns blue litmus red | Turns red litmus blue |
| pH < 7 | pH > 7 |
| Releases H⁺ ions | Releases OH⁻ ions |

**c. State three properties of acids.**

**Answer:**
1. Acids have sour taste
2. Acids turn blue litmus paper red
3. Acids react with metals to produce hydrogen gas

**d. Write the chemical equation for neutralization reaction.**

**Answer:** 
**General equation:** Acid + Base → Salt + Water
**Example:** HCl + NaOH → NaCl + H₂O

**e. What is pH scale? What is its range?**

**Answer:** pH scale is a measure of hydrogen ion concentration in solution. Its range is 0 to 14.
- pH < 7: Acidic
- pH = 7: Neutral  
- pH > 7: Basic

**f. Name three natural indicators.**

**Answer:**
1. Litmus (from lichens)
2. Turmeric
3. Red cabbage

**g. What is the chemical name of:**
**i. Common salt:** Sodium chloride (NaCl)
**ii. Caustic soda:** Sodium hydroxide (NaOH)
**iii. Washing soda:** Sodium carbonate (Na₂CO₃·10H₂O)

**h. Write two uses each of acids and bases.**

**Answer:**
**Acids:**
1. HCl used in stomach for digestion
2. H₂SO₄ used in car batteries

**Bases:**
1. NaOH used in soap making
2. Ca(OH)₂ used in whitewashing

### **3. Define the following:**

**a. Neutralization:** The reaction between acid and base to form salt and water.

**b. Indicator:** Substances that show different colors in acidic and basic solutions.

**c. Universal indicator:** An indicator that shows different colors for different pH values.

**d. Salt:** A compound formed when hydrogen ions of acid are replaced by metal ions.

**e. Alkali:** Water-soluble bases that release OH⁻ ions in solution.

**f. Strong acid:** Acid that completely ionizes in water (HCl, H₂SO₄, HNO₃).

**g. Weak base:** Base that partially ionizes in water (NH₄OH, Mg(OH)₂).

### **4. Give reasons:**

**a. Acids taste sour.**

**Answer:** Acids contain hydrogen ions (H⁺) which give sour taste when they come in contact with taste buds.

**b. Bases feel slippery.**

**Answer:** Bases react with oils and fats in skin to form soap-like substances, making them feel slippery.

**c. Dry HCl gas does not change litmus paper color.**

**Answer:** HCl releases H⁺ ions only in presence of water. Dry HCl gas contains no H⁺ ions, so no color change.

**d. We should not add water to concentrated acid.**

**Answer:** Adding water to concentrated acid releases large amount of heat which can cause the mixture to splash and cause burns.

**e. Antacids are used to treat acidity.**

**Answer:** Antacids are basic in nature and neutralize excess acid in stomach, providing relief from acidity.

**f. Tooth decay occurs when pH in mouth is below 5.5.**

**Answer:** When pH drops below 5.5, acid corrodes tooth enamel (calcium phosphate), leading to tooth decay.

**g. Distilled water does not conduct electricity.**

**Answer:** Pure distilled water has very few ions, so it cannot conduct electricity. Conductivity requires ions.

**h. Lime water turns milky with CO₂.**

**Answer:** CO₂ reacts with lime water to form insoluble calcium carbonate which makes the solution milky.
**Ca(OH)₂ + CO₂ → CaCO₃↓ + H₂O**

### **5. Distinguish between:**

**a. Strong acid and Weak acid**

| Strong Acid | Weak Acid |
|-------------|-----------|
| Completely ionizes in water | Partially ionizes in water |
| pH: 0-3 | pH: 3-6 |
| Examples: HCl, H₂SO₄ | Examples: CH₃COOH, H₂CO₃ |
| Good conductor of electricity | Poor conductor of electricity |

**b. Acid salt and Basic salt**

| Acid Salt | Basic Salt |
|-----------|------------|
| Contains replaceable H atoms | Contains OH groups |
| pH < 7 | pH > 7 |
| Examples: NaHSO₄, KHCO₃ | Examples: Mg(OH)Cl, Cu(OH)Cl |
| Formed by partial neutralization | Formed by partial neutralization |

**c. Concentrated acid and Dilute acid**

| Concentrated Acid | Dilute Acid |
|-------------------|-------------|
| Contains more acid, less water | Contains less acid, more water |
| Higher concentration | Lower concentration |
| More corrosive | Less corrosive |
| Example: Conc. H₂SO₄ | Example: 0.1 M HCl |

### **6. Numerical Problems:**

#### **Problem Type 1: pH Calculations**

**Q1:** Calculate the pH of 0.01 M HCl solution.

**Given:**
- [HCl] = 0.01 M = 1 × 10⁻² M
- HCl → H⁺ + Cl⁻

**Solution:**
[H⁺] = [HCl] = 1 × 10⁻² M
pH = -log[H⁺] = -log(1 × 10⁻²) = -(-2) = 2

**Answer:** pH = 2

**Q2:** What is the pH of 0.001 M NaOH solution?

**Given:**
- [NaOH] = 0.001 M = 1 × 10⁻³ M
- NaOH → Na⁺ + OH⁻

**Solution:**
[OH⁻] = [NaOH] = 1 × 10⁻³ M
pOH = -log[OH⁻] = -log(1 × 10⁻³) = 3
pH = 14 - pOH = 14 - 3 = 11

**Answer:** pH = 11

**Q3:** Calculate [H⁺] if pH = 3.

**Solution:**
pH = -log[H⁺]
3 = -log[H⁺]
log[H⁺] = -3
[H⁺] = 10⁻³ M = 0.001 M

**Answer:** [H⁺] = 0.001 M

#### **Problem Type 2: Neutralization Problems**

**Q4:** How many moles of NaOH are needed to neutralize 0.1 mole of H₂SO₄?

**Given:**
- H₂SO₄ = 0.1 mole (dibasic acid)
- H₂SO₄ + 2NaOH → Na₂SO₄ + 2H₂O

**Solution:**
From balanced equation: 1 mole H₂SO₄ reacts with 2 moles NaOH
0.1 mole H₂SO₄ will react with = 0.1 × 2 = 0.2 mole NaOH

**Answer:** 0.2 mole NaOH required

**Q5:** What volume of 0.1 M HCl is needed to neutralize 25 mL of 0.1 M NaOH?

**Given:**
- NaOH: 0.1 M, 25 mL
- HCl: 0.1 M, V = ?
- HCl + NaOH → NaCl + H₂O

**Solution:**
For neutralization: Moles of acid = Moles of base
M₁V₁ = M₂V₂
0.1 × V₁ = 0.1 × 25
V₁ = 25 mL

**Answer:** 25 mL of 0.1 M HCl required

### **7. Diagrammatic Questions:**

#### **Question 1: Setup for preparation of CO₂ gas**
**Draw and label the apparatus for laboratory preparation of CO₂.**

**Answer:** 
**Apparatus:** Conical flask, thistle funnel, delivery tube, gas jar
**Reaction:** CaCO₃ + 2HCl → CaCl₂ + H₂O + CO₂↑
**Collection:** Downward displacement of air (CO₂ is denser than air)

#### **Question 2: Neutralization reaction**
**Show the reaction between HCl and NaOH using chemical equation.**

**Answer:**
**Molecular equation:** HCl + NaOH → NaCl + H₂O
**Ionic equation:** H⁺ + Cl⁻ + Na⁺ + OH⁻ → Na⁺ + Cl⁻ + H₂O
**Net ionic equation:** H⁺ + OH⁻ → H₂O

#### **Question 3: pH scale diagram**
**Draw pH scale showing acidic, neutral, and basic regions.**

**Answer:**
```
0----1----2----3----4----5----6----7----8----9----10----11----12----13----14
|    ACIDIC REGION    |NEUTRAL|         BASIC REGION           |
     Strong Acid              Weak Base    Strong Base
```

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## 📈 8. IMPORTANT FORMULAS SUMMARY

### **pH Calculations:**
- pH = -log[H⁺]
- pOH = -log[OH⁻]  
- pH + pOH = 14
- [H⁺] × [OH⁻] = 1 × 10⁻¹⁴

### **Neutralization:**
- Acid + Base → Salt + Water
- At equivalence point: Moles of H⁺ = Moles of OH⁻

### **Salt Formation:**
- Strong acid + Strong base → Neutral salt (pH = 7)
- Strong acid + Weak base → Acidic salt (pH < 7)
- Weak acid + Strong base → Basic salt (pH > 7)

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## 🎯 9. EXAM PREPARATION TIPS

### **Theory Questions (2-3 marks)**
- Learn exact definitions with examples
- Remember all chemical reactions
- Understand properties of acids, bases, salts
- Practice identifying different types of salts

### **Numerical Problems (3-4 marks)**
- Master pH and pOH calculations
- Practice neutralization stoichiometry
- Learn molarity and concentration problems
- Show all calculation steps clearly

### **Give Reason Questions (2-3 marks)**
- Connect chemical properties to explanations
- Use ionic theory for reasoning
- Remember daily life applications
- Practice explaining indicator behavior

### **Long Questions (5-6 marks)**
- Complete salt preparation methods
- Detailed explanation of pH scale
- Properties and uses of important compounds
- Industrial preparation processes

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## 🏆 10. PREVIOUS YEAR SEE QUESTIONS PATTERN

### **Theory Questions**
- Definition and properties of acids/bases/salts
- Types of salts and their formation
- pH scale and its importance
- Uses of important compounds
- Chemical reactions with balanced equations

### **Numerical Questions**
- pH and pOH calculations
- Neutralization problems
- Molarity calculations
- Stoichiometry problems

### **Practical Questions**
- Laboratory preparation of salts
- Indicator color changes
- Testing acidic/basic nature
- Industrial processes

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## ✅ 11. CHAPTER CHECKLIST

**Before SEE Exam, ensure you can:**
- [ ] Define acids, bases, and salts correctly
- [ ] Write and balance all chemical reactions
- [ ] Calculate pH and pOH values
- [ ] Explain properties using ionic theory
- [ ] Identify types of salts and their preparation
- [ ] Solve neutralization problems
- [ ] Remember uses of important compounds
- [ ] Explain daily life applications

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## 🎊 CONCLUSION

**This note includes all the exercises given in Acid, Base and Salt chapter of science book such as question answer, numericals, give reason, diagrammatic questions and define the following exactly as promised.** The chapter forms the foundation of chemistry understanding with practical applications in daily life. Master the definitions, chemical reactions, pH calculations, and salt preparation methods for excellent SEE performance.

**Success Formula:** 
Definition Mastery + Reaction Practice + pH Calculations + Daily Life Applications = Chemistry Excellence!

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*These comprehensive notes are published for helping students to solve their problems related to Acid, Base and Salt chapter. Study systematically, practice numerical problems regularly, and connect chemistry concepts to everyday life for complete understanding and excellent examination results.*

**📞 Need Help?** Focus on chemical equation balancing and pH calculations for strong foundation in acid-base chemistry concepts.

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