Class 10th Science Chapter:- 2 Acids,Bases and Salt

              Class 10th Science Chapter :- 2

                      Acid, Base, and Salt:-

1. Acid

An acid is a substance that increases the concentration of hydrogen ions (H⁺) or hydronium ions (H₃O⁺) in an aqueous solution. Acids have a sour taste, turn blue litmus paper red, and react with bases to form salts and water.

Key Characteristics of Acids:

• pH value: Less than 7
• Taste: Sour
• Effect on Litmus: Turns blue litmus red
• Conductivity: Conducts electricity in solution
• Reaction with Metals: Produces hydrogen gas (H₂)
• Reaction with Bases: Forms salt and water (Neutralization reaction)

Examples of Acids:

• Hydrochloric acid (HCl) – Found in stomach acid
• Sulfuric acid (H₂SO₄) – Used in car batteries
• Nitric acid (HNO₃) – Used in fertilizers
• Acetic acid (CH₃COOH) – Found in vinegar
• Citric acid (C₆H₈O₇) – Found in citrus fruits

Types of Acids:

1. Strong Acids – Completely ionize in water (e.g., HCl, H₂SO₄)
2. Weak Acids – Partially ionize in water (e.g., CH₃COOH)
3. Organic Acids – Contain carbon and are weak acids (e.g., citric acid)
4. Inorganic Acids – Do not contain carbon and can be strong or weak (e.g., HCl, H₂SO₄)

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2. Base

A base is a substance that increases the concentration of hydroxide ions (OH⁻) in an aqueous solution. Bases have a bitter taste, turn red litmus paper blue, and react with acids to form salts and water.

Key Characteristics of Bases:

• pH value: Greater than 7
• Taste: Bitter
• Feel: Soapy or slippery
• Effect on Litmus: Turns red litmus blue
• Conductivity: Conducts electricity in solution
• Reaction with Acids: Forms salt and water (Neutralization reaction)

Examples of Bases:

• Sodium hydroxide (NaOH) – Used in soap making
• Potassium hydroxide (KOH) – Used in alkaline batteries
• Calcium hydroxide (Ca(OH)₂) – Used in cement
• Ammonium hydroxide (NH₄OH) – Used in household cleaners

Types of Bases:

1. Strong Bases – Completely ionize in water (e.g., NaOH, KOH)
2. Weak Bases – Partially ionize in water (e.g., NH₄OH)
3. Alkalis – Bases that are soluble in water (e.g., NaOH, KOH)
4. Non-Alkali Bases – Bases that are insoluble in water (e.g., Cu(OH)₂, Fe(OH)₃)

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3. Salt

A salt is a compound formed when an acid reacts with a base in a neutralization reaction, producing water as a byproduct. Salts are ionic compounds made up of positively charged cations (metal or ammonium ion) and negatively charged anions (non-metal or polyatomic ion).

Key Characteristics of Salts:

• Usually neutral (pH ≈ 7), but some salts can be acidic or basic
• Generally soluble in water, but some are insoluble
• Can be crystalline solids
• Conduct electricity when dissolved in water (electrolytes)

Formation of Salt (Neutralization Reaction):

$$\text{Acid} + \text{Base} → \text{Salt} + \text{Water}$$

Examples of Salts:

• Sodium chloride (NaCl) – Table salt, formed from HCl and NaOH
• Potassium nitrate (KNO₃) – Used in fertilizers, formed from HNO₃ and KOH
• Calcium sulfate (CaSO₄) – Used in plaster, formed from H₂SO₄ and Ca(OH)₂
• Ammonium chloride (NH₄Cl) – Used in dry cells, formed from HCl and NH₄OH

Types of Salts:

1. Neutral Salts – Formed from a strong acid and strong base (e.g., NaCl)
2. Acidic Salts – Formed from a strong acid and weak base (e.g., NH₄Cl)
3. Basic Salts – Formed from a strong base and weak acid (e.g., CH₃COONa)
4. Double Salts – Contain two different cations (e.g., Potash alum – K₂SO₄·Al₂(SO₄)₃·24H₂O)

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Summary Table

Property	Acid	Base	Salt
Definition	Produces H⁺/H₃O⁺ ions	Produces OH⁻ ions	Formed from acid-base reaction
pH	< 7	> 7	~7 (can vary)
Taste	Sour	Bitter	Varies
Litmus Test	Turns blue litmus red	Turns red litmus blue	No effect (usually)
Reaction with Metals	Produces H₂ gas	No reaction	No reaction
Reaction with Acids/Bases	Neutralizes bases	Neutralizes acids	Formed from acid and base

Indicators: Detailed Definition and Explanation

What is an Indicator?

An indicator is a substance that changes color in response to a change in pH, helping to determine whether a solution is acidic, basic, or neutral. Indicators are widely used in chemistry, biology, and environmental science for qualitative analysis of substances.

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Types of Indicators

Indicators can be classified into different types based on their sources and working principles:

1. Acid-Base Indicators (pH Indicators)

These indicators change color at different pH levels and are used to identify whether a solution is acidic or basic.

Examples of Acid-Base Indicators:

Indicator	Acidic Solution (pH < 7)	Neutral Solution (pH = 7)	Basic Solution (pH > 7)
Litmus	Red	Purple	Blue
Methyl Orange	Red	Orange	Yellow
Phenolphthalein	Colorless	Colorless	Pink
Bromothymol Blue	Yellow	Green	Blue
Universal Indicator	Red/Orange	Green	Blue/Violet

• Litmus Paper: Made from natural dyes and turns red in acidic solutions and blue in basic solutions.

• Universal Indicator: A mixture of indicators that shows different colors over a wide pH range.

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2. Natural Indicators

These indicators are obtained from natural sources, such as plants, and change color in response to pH.

Examples:

• Turmeric: Yellow in acids, turns reddish-brown in bases.

• Red Cabbage Extract: Red in acids, purple in neutral solutions, and green/yellow in bases.

• China Rose (Hibiscus): Dark pink in acids, green in bases.

• Beetroot Juice: Pink in acids, yellow in bases.

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3. Olfactory Indicators (Smell Indicators)

These indicators change their odor in acidic or basic solutions.

Examples:

• Vanilla Extract: Loses its smell in a basic solution but retains it in an acidic solution.

• Onion Extract: Loses its strong smell in a basic solution but retains it in an acidic solution.

• Clove Oil: Loses its characteristic smell in a basic solution.

Types of Acids and Bases (For Class 10) – Detailed Explanation

Acids and bases can be classified based on different factors such as strength, source, and composition. Let’s break them down into categories.

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Types of Acids

Acids can be classified based on:

1. Strength (Strong or Weak Acids)
2. Source (Organic or Inorganic Acids)
3. Basicity (Monobasic, Dibasic, or Tribasic Acids)
4. Concentration (Dilute or Concentrated Acids)
5. Volatility (Volatile or Non-Volatile Acids)

1. Classification Based on Strength

(a) Strong Acids: These acids completely ionize in water, releasing a high concentration of H⁺ ions.
Examples:

• Hydrochloric Acid (HCl) – Found in stomach acid
• Sulfuric Acid (H₂SO₄) – Used in car batteries
• Nitric Acid (HNO₃) – Used in fertilizers

(b) Weak Acids: These acids partially ionize in water, releasing fewer H⁺ ions.
Examples:

• Acetic Acid (CH₃COOH) – Found in vinegar
• Carbonic Acid (H₂CO₃) – Present in soft drinks
• Citric Acid (C₆H₈O₇) – Found in citrus fruits

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2. Classification Based on Source

(a) Organic Acids: These acids are derived from living organisms (plants or animals). They are usually weak acids.
Examples:

• Acetic Acid (CH₃COOH) – Vinegar
• Citric Acid (C₆H₈O₇) – Found in lemons and oranges
• Lactic Acid (C₃H₆O₃) – Found in curd

(b) Inorganic (Mineral) Acids: These acids are derived from minerals and are usually strong.
Examples:

• Hydrochloric Acid (HCl) – Found in gastric juice
• Sulfuric Acid (H₂SO₄) – Used in batteries
• Phosphoric Acid (H₃PO₄) – Used in fertilizers

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3. Classification Based on Basicity (Number of H⁺ Ions Released)

(a) Monobasic Acids: Acids that release only one H⁺ ion per molecule in solution.
Examples:

• Hydrochloric Acid (HCl)
• Nitric Acid (HNO₃)

(b) Dibasic Acids: Acids that release two H⁺ ions per molecule.
Examples:

• Sulfuric Acid (H₂SO₄)
• Carbonic Acid (H₂CO₃)

(c) Tribasic Acids: Acids that release three H⁺ ions per molecule.
Examples:

• Phosphoric Acid (H₃PO₄)
• Citric Acid (C₆H₈O₇)

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4. Classification Based on Concentration

(a) Dilute Acids: Contain a small amount of acid dissolved in water.
Example: Dilute HCl, Dilute H₂SO₄

(b) Concentrated Acids: Contain a large amount of acid and very little water.
Example: Concentrated HCl, Concentrated H₂SO₄

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5. Classification Based on Volatility

(a) Volatile Acids: These acids easily evaporate at room temperature.
Examples:

• Hydrochloric Acid (HCl)
• Nitric Acid (HNO₃)

(b) Non-Volatile Acids: These acids do not evaporate easily.
Examples:

• Sulfuric Acid (H₂SO₄)
• Phosphoric Acid (H₃PO₄)

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Types of Bases

Bases can also be classified based on:

1. Strength (Strong or Weak Bases)
2. Solubility (Alkalis or Insoluble Bases)
3. Acidity of the Base (Monoacidic, Diacidic, or Triacidic Bases)
4. Concentration (Dilute or Concentrated Bases)

1. Classification Based on Strength

(a) Strong Bases: These bases completely ionize in water, releasing a high concentration of OH⁻ ions.
Examples:

• Sodium Hydroxide (NaOH) – Used in soap making
• Potassium Hydroxide (KOH) – Used in alkaline batteries
• Calcium Hydroxide (Ca(OH)₂) – Used in cement

(b) Weak Bases: These bases partially ionize in water, releasing fewer OH⁻ ions.
Examples:

• Ammonium Hydroxide (NH₄OH) – Used in household cleaners
• Magnesium Hydroxide (Mg(OH)₂) – Used as an antacid (Milk of Magnesia)

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2. Classification Based on Solubility

(a) Alkalis (Soluble Bases): Bases that dissolve in water and release OH⁻ ions.
Examples:

• Sodium Hydroxide (NaOH)
• Potassium Hydroxide (KOH)

(b) Insoluble Bases: Bases that do not dissolve in water.
Examples:

• Copper Hydroxide (Cu(OH)₂)
• Iron (III) Hydroxide (Fe(OH)₃)

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3. Classification Based on Acidity of the Base (Number of OH⁻ Ions Released)

(a) Monoacidic Bases: Bases that release one OH⁻ ion per molecule.
Examples:

• Sodium Hydroxide (NaOH)
• Potassium Hydroxide (KOH)

(b) Diacidic Bases: Bases that release two OH⁻ ions per molecule.
Examples:

• Calcium Hydroxide (Ca(OH)₂)
• Magnesium Hydroxide (Mg(OH)₂)

(c) Triacidic Bases: Bases that release three OH⁻ ions per molecule.
Examples:

• Aluminum Hydroxide (Al(OH)₃)
• Ferric Hydroxide (Fe(OH)₃)

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4. Classification Based on Concentration

(a) Dilute Bases: Contain a small amount of base dissolved in water.
Example: Dilute NaOH, Dilute KOH

(b) Concentrated Bases: Contain a large amount of base and very little water.
Example: Concentrated NaOH, Concentrated KOH

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