Inorganic Compounds and Their Properties

3.1 Introduction

• Inorganic compounds are all compounds that do not contain carbon (except simpler carbon compounds like oxides, carbonates, and carbides).
• They consist of minerals from the earth and are found in nonliving things.
• Compounds in living organisms are organic in nature.
• Most metal compounds are inorganic.
• Common inorganic compounds in nature include silicates, oxides, carbonates, sulphides, sulphates, chlorides, nitrates, etc.

3.2 Oxides

• Formation: Oxides are formed by the reaction between metals, non-metals, or metalloids and oxygen.
• Chemical Reaction:
  • $ext{Metal/Non-metal/Metalloid} + O_2 o ext{Oxides}$

A. Acidic Oxides

• Formed by oxygen with nonmetals from Groups 14-17 (non-metal oxides).
• Examples:
  • $ext{CO}<em>2$, $ext{NO}</em>2$, $ext{SO}_2$
• Some acidic oxides (e.g., $ext{SiO}_2$) do not react directly with water but can form acids by other methods.

Chemical Properties

1. Dissolve in water, forming acidic solutions:
   • $ext{Acid anhydride} + ext{Water} o ext{Acid}$
     • $ext{CO}<em>2 + ext{H}</em>2O o ext{H}<em>2 ext{CO}</em>3$
2. React with basic or metallic oxides to form salt:
   • $ext{Acidic oxide} + ext{Basic oxide} o ext{Salt}$
3. React with bases to form salt and water (neutralization):
   • $ext{Acidic oxide} + ext{Base} o ext{Salt} + ext{Water}$

Basic Oxides

• Composed of metals and oxygen.
• Examples: $ext{Li}<em>2 ext{O}$, $ext{Na}</em>2 ext{O}$, $ext{K}_2 ext{O}$, $ext{MgO}$, $ext{CaO}$, $ext{BaO}$, $ext{CuO}$.

Chemical Properties

1. Dissolve in water, forming alkaline solutions:
   • $ext{Basic oxide} + ext{Water} o ext{Base (Alkali)}$
2. React with acidic oxides to form salts.
3. React with acids to form salt and water (neutralization).

C. Amphoteric Oxides

• Characterized by showing both acidic and basic behavior.
• Examples: $ext{Al}<em>2 ext{O}</em>3$, $ext{ZnO}$, $ext{PbO}$, $ext{SnO}_2$.

D. Neutral Oxides

• Do not react with acids or bases.
• Examples: Water ($ext{H}<em>2 ext{O}$), carbon monoxide ($ext{CO}$), dinitrogen monoxide ($ext{N}</em>2O$).

E. Peroxides

• Contain $ext{O}_2^{2-}$ : Oxidation number of oxygen is -1.
• Examples: $ext{H}<em>2 ext{O}</em>2$, $ext{Na}<em>2 ext{O}</em>2$.

Chemical Properties

1. Powerful oxidizing agents that react by losing oxygen.
2. React with acids to form hydrogen peroxide.

F. Superoxides

• Oxidation number of oxygen is -0.5 (containing $ext{O}_2^{-}$).
• Examples: $ext{KO}<em>2$ and $ext{RbO}</em>2$.

3.3 Acids

General Properties

• Taste: Sour, e.g., vinegar contains acetic acid.
• Indicators: Change litmus from blue to red.
• React with metals to produce hydrogen gas. e.g., $2 ext{HCl}(aq) + ext{Mg} o ext{MgCl}<em>2(aq) + ext{H}</em>2(g)$.

Classification of Acids

A. Based on Ionizable Hydrogen Ions

• Monoprotic: One ionizable H (e.g., $ext{HCl}$).
• Diprotic: Two ionizable H (e.g., $ext{H}<em>2 ext{SO}</em>4$).
• Triprotic: Three ionizable H (e.g., $ext{H}<em>3 ext{PO}</em>4$).

B. Based on Elements

• Binary acids: Two elements (e.g., $ext{HCl}$).
• Ternary acids: Three elements, usually including oxygen (e.g., $ext{H}<em>2 ext{SO}</em>4$).

C. Based on Strength

• Strong acids: Completely dissociate (e.g., $ext{HCl}, ext{HNO}_3$).
• Weak acids: Partially dissociate (e.g., $ext{CH}_3 ext{COOH}$).

3.5 Salts

• Formed from the neutralization of an acid and base.
• Names derived from metals and acids, following specific naming conventions:
  • Oxygen-free acids: Hydro- prefix dropped, ending -ic changes to -ide (e.g., $ext{NaCl}$).
  • Oxyacids: Ending -ic changes to -ate, -ous to -ite (e.g., $ext{KNO}_3$ to potassium nitrate).

Precautions in Handling Acids and Bases

• For Acids: Wear goggles, gloves, wash spills, dilute acid in water, seek medical help for spills.
• For Bases: Use protective gear, rinse spills, wash affected areas immediately.

pH Measurement

• pH is the measure of acidity in a solution, scale 0-14.
• Neutral water has a pH of 7.
• pH can be calculated using:
  • $ext{pH} = - ext{log}[ ext{H}^+]$
  • $ext{pH} + ext{pOH} = 14$.

Examples of Reactions Leading to Preparation of Acids

• Reaction of oxides with water, direct combination of nonmetals, heating salts with non-volatile acid.