Chemical Reactions

Chemical Reactions

Definition: Process where reactants form products (REACTANTS → PRODUCTS)Example: 2 hydrogen (H2) + oxygen (O2) → 2 water (H2O)

Types of Reactions

• Exothermic: Release thermal energy (e.g., Sodium + water → sodium hydroxide + hydrogen)

• Endothermic: Absorb thermal energy (e.g., Ice melting, cold packs)

• Combustion: Fuel reacts with oxygen (e.g., Carbon + oxygen → carbon dioxide)

• Oxidation: Combines with oxygen (All combustion reactions are oxidation but not vice versa)

Reactions in Lab

• Common examples: Sodium hydroxide + hydrochloric acid → sodium chloride + water; Acetic acid + sodium bicarbonate → sodium acetate + carbon dioxide + water

• Record initial and final temperatures.

Rusting of Metals

• Reaction: Iron + oxygen → iron oxide (rust); Water needed, salt accelerates rusting.

• Prevention: Painting, oil coating, galvanization, chrome plating.

Reactions with Water

• General: Metal + water → metal hydroxide + hydrogen; Example: Potassium + water → potassium hydroxide + hydrogen.

Reactivity of Metals

• Reactivity Series: Potassium reacts vigorously; Gold does not react with acids.

• Mnemonic: Helps remember reactivity order.