Chemical Reactions and Equations
1. Chemical Reactions and Equations Chemical Reaction A process in which new substances are formed with different properties. Indicators of Chemical Reaction: ∙ Change in color ∙ Evolution of gas ∙ Formation of precipitate ∙ Change in temperature ∙ Change in state Chemical Equation Symbolic representation of a chemical reaction. ∙ Unbalanced equation: Zn + HCl → ZnCl₂ + H₂ ∙ Balanced equation: Zn + 2HCl → ZnCl₂ + H₂ Types of Chemical Reactions: 1. Combination Reaction Two or more substances combine to form a single product. ∙ Example: CaO + H₂O → Ca(OH)₂ ∙ Example: C + O₂ → CO₂ 2. Decomposition Reaction A single substance breaks down into two or more products. ∙ Thermal decomposition: 2FeSO₄ →(heat) Fe₂O₃ + SO₂ + SO₃ ∙ Electrolytic decomposition: 2H₂O →(electricity) 2H₂ + O₂ ∙ Photochemical decomposition: 2AgCl →(sunlight) 2Ag + Cl₂ 3. Displacement Reaction A more reactive element displaces a less reactive element from its compound. ...