Study guide: Acids Bases and Salts

📋 Course Outline

1. Acid and Base Concepts
2. Bronsted-Lowry Proton Transfer
3. Strength and Dissociation
4. Alkalis and Metallic Bases
5. Characteristic Acid Reactions
6. Characteristic Base Reactions
7. Metal Oxides and Acid Rain

📖 1. Acid and Base Concepts

🔑 Key Concepts & Definitions

• Arrhenius acid: Svante Arrhenius, 1887 — a substance that ionizes in water to produce H+ ions
• Arrhenius base: Svante Arrhenius, 1887 — a substance that ionizes in water to produce OH− ions

📝 Essential Points

• Aqueous solutions of acids contain H+ ions, while aqueous solutions of bases contain OH− ions and conduct electricity.

• Acids turn blue litmus red and generally taste sour, whereas bases turn red litmus blue and generally taste bitter.

💡 Memory Hook

Acids donate or produce H+, whereas bases accept protons or produce OH−.

📖 2. Bronsted-Lowry Proton Transfer

🔑 Key Concepts & Definitions

• Bronsted-Lowry acid: a proton donor
• Bronsted-Lowry base: a proton acceptor

📝 Essential Points

📌 In the reaction $HCl + H_2O \longrightarrow H_3O^+ + Cl^-$, HCl is the proton donor and acid, while H2O is the proton acceptor and base.

📌 Water is amphoteric because it can donate a proton in one reaction and accept a proton in another.

💡 Memory Hook

Donate proton → negative conjugate ion; accept proton → positive conjugate ion.

📖 3. Strength and Dissociation

🔑 Key Concepts & Definitions

• Strong acid: ionizes completely, or 100%, in aqueous solution; examples include HCl, HNO3, and H2SO4
• Weak acid: ionizes only partially in aqueous solution; ethanoic acid ionizes up to 5% in water
• Strong base: ionizes completely, or 100%, in aqueous solution; examples include NaOH, KOH, and Ca(OH)2
• Weak base: ionizes only to a small extent in aqueous solution and produces fewer OH− ions; examples include Al(OH)3 and NH3

💡 Memory Hook

Strong acids and bases dissociate completely, whereas weak ones dissociate partially.

📖 4. Alkalis and Metallic Bases

🔑 Key Concepts & Definitions

• Alkali: a base that is soluble in water, so every alkali is a base but not every base is an alkali
• Amphoteric oxide: behaves like both an acid and a base in chemical reactions; examples include aluminium oxide and zinc oxide

📝 Essential Points

• Examples of insoluble bases are:
  • Copper hydroxide
  • aluminium hydroxide
  • ferric hydroxide

💡 Memory Hook

Every alkali is a base, but not every base is an alkali.

📖 5. Characteristic Acid Reactions

🔑 Key Concepts & Definitions

• Neutralization reaction: occurs when an acid reacts with a base to produce a salt and water

★ Must-know

• Acids react with metals to form a salt and hydrogen gas.

• Acids react with metal carbonates to form a salt, water, and carbon dioxide.

Further detail

• Hydrochloric acid reacts with sodium hydroxide to form sodium chloride and water: $HCl + NaOH \rightarrow NaCl + H_2O$.

💡 Memory Hook

Acid + metal → hydrogen; acid + carbonate → carbon dioxide; acid + base → water.

📖 6. Characteristic Base Reactions

★ Must-know

📌 Bases neutralize acids to form salt and water.

• Bases decompose ammonium salts on heating and liberate ammonia gas.

Further detail

• Bases have a bitter taste, turn red litmus blue, and their aqueous solutions have a slippery touch.

• Sodium hydroxide reacts with ammonium chloride to form sodium chloride, ammonia, and water: $NaOH + NH_4Cl \rightarrow NaCl + NH_3 + H_2O$.

💡 Memory Hook

Base + acid → salt and water; base + ammonium salt → ammonia.

📖 7. Metal Oxides and Acid Rain

🔑 Key Concepts & Definitions

• Acid rain: rain made more acidic when acid oxides enter the atmosphere; it contains dissolved nitric and sulphuric acids

★ Must-know

📌 Because of their corrosive nature, acid rain can damage structures, buildings, and statues containing metals and metal carbonates.

• Metal oxides form when metals react with oxygen, and metal oxides react with water to form metal hydroxides.

Further detail

• Sodium oxide reacts with water to form sodium hydroxide: $Na_2O + H_2O \rightarrow 2NaOH$.

• Examples of amphoteric hydroxides include aluminium hydroxide, Al(OH)3, and zinc hydroxide, Zn(OH)2.

💡 Memory Hook

Acid oxides enter the atmosphere → rain becomes more acidic → structures are damaged.

📊 Synthesis Tables

Acid and Base Comparisons