Lecture Notes: Preparation for Board Examinations

Introduction

• Always smile, hide your sorrow.
• Board exams are near, avoid demotivation and work hard.
• Like, attendance, and check Telegram updates.
• Today's chapter: Acids, Bases, and Salts

Attendance & Engagement

• Students asked about attendance and enthusiasm levels.
• Requested students' feedback and engagement for videography.
• Notes and other materials made available via links in the description on Telegram.

Acids, Bases, and Salts Overview

• Very simple chapter that, once understood, ensures ease until finals.
• The entire chapter will be covered in one and a half to two hours.

What is an Acid?

• Definition: Hydrogen-containing substance capable of donating protons.
• Example: H2SO4, HNO3, HCl
• Properties: Turns blue litmus red, sour taste.
• Examples in real life: Lactic acid in muscles.

What is a Base?

• Definition: Substances that release hydroxide ions (OH-) in water.
• Properties: Bitter taste, turns red litmus blue.
• Examples: NaOH, KOH.

Alkalies

• Soluble bases in water are called alkalies.
• Examples: NaOH, KOH, Ca(OH)2.

What is a Salt?

• Produced when acid reacts with a base: Salt and Water.
• Can be acidic or basic.

Reactions with Acids

• Acid + Metal → Salt + Hydrogen gas.
• Acid + Metal Oxide → Salt + Water.
• Acid + Metal Carbonate/Bicarbonate → Salt + Water + CO2.

Identifying Acids/Bases Using Indicators

• Litmus Test: Blue litmus turns red in acid, red litmus turns blue in base.
• Turmeric Indicator: No change with acid, red with base.
• Phenolphthalein Indicator: Colorless with acid, pink with base.
• Methyl Orange Indicator: Red with acid, yellow with base.
• Universal indicators and pH scale: Measures acidity or basicity.

pH Scale

• 0-14 scale, 7 is neutral.
• Below 7: Acidic.
• Above 7: Basic.

Properties and Uses of Specific Compounds

Sodium Hydroxide (NaOH)

• Preparation: Electrolysis of brine solution.
• Uses: Soap making, paper making, artificial fibers.

Hydrochloric Acid (HCl)

• Cleaning steel, making ammonium chloride, in medicines and cosmetics.

Bleaching Powder

• Formula: Ca(OCl)2.
• Preparation: Reaction of chlorine with calcium hydroxide.
• Uses: Bleaching cotton, as an oxidizing agent, disinfecting water.

Baking Soda (NaHCO3)

• Preparation: Reaction of brine solution with ammonia and CO2.
• Uses: Antacid, baking powder, cleaning agent.

Washing Soda (Na2CO3·10H2O)

• Formed by heating NaHCO3.
• Uses: Removing permanent water hardness, cleaning agent in laundry.

Plaster of Paris (CaSO4·1/2H2O)

• Preparation: Heating gypsum (CaSO4·2H2O) at 373K.
• Uses: Building material, making ornaments, fire protection.

Water of Crystallization

• Water molecules in a crystalline substance.
• Example: CuSO4·5H2O.

Recap & Conclusion

• Importance of understanding basics for better performance.
• Encouragement to solve practice problems and revision regularly.

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