Study sheet: 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

Property	Acids	Bases
Taste	Sour	Bitter
Blue litmus	Turns red	No effect
Red litmus	No effect	Turns blue
Aqueous electrical conductivity	Conducts electricity	Conducts electricity