Unit 1: Introduction, Laboratory Safety and Waste Management

• Types of matter

  • Substances
  • Mixtures
  • Elements
  • Compounds
• Substance


  A form of matter that has a definite composition and distinct properties
• Mixture


  A combination of two or more substances in which the substances retain their distinct identities
• Homogeneous mixture


  Composition is the same throughout
• Heterogeneous mixture


  Composition is not uniform
• Mixtures can be separated by physical means into pure components without changing the identities of the components
• Element


  A substance that cannot be separated into simpler substances by chemical means
• Compound


  Composed of atoms of two or more elements chemically united in fixed proportions
• Compounds can be separated only by chemical means into their pure components
• States of matter

  • Solid
  • Liquid
  • Gas
• Physical property


  Can be measured and observed without changing the composition or identity of a substance
• Examples of physical properties

  • Color
  • Melting point
  • Boiling point
• Chemical property


  Characteristic of a substance observed during a reaction in which the chemical composition or identity of the substance is changed
• All measurable properties of matter fall into extensive or intensive properties
• Extensive property


  Depends on how much matter is being considered
• Examples of extensive properties

  • Mass
  • Length
  • Volume
• Intensive property


  Does not depend on how much matter is being considered
• Examples of intensive properties

  • Color
  • Odor
  • Taste
  • Density
  • Temperature
• Chemical reaction


  A process in which a substance is changed into one or more new substances
• Chemical equation


  A shorthand method of representing chemical reaction using chemical symbols and formulas
• Reactants are the starting materials in a chemical reaction
• Products are the substances formed as a result of a chemical reaction
• In a chemical equation, reactants are conventionally written on the left and products on the right of the arrow
• Law of Conservation of Mass


  In chemical reactions, atoms are neither created nor destroyed
• r solid, and aq for aqueous
• Knowing the states of the reactants and products is especially useful in the laboratory
• When potassium bromide (KBr) and silver nitrate (AgNO3) react in an aqueous environment


  A solid, silver bromide (AgBr), is formed
• Reaction of KBr and AgNO3

  1. KBr(aq) + AgNO3(aq)

  2. KNO3(aq) + AgBr(s)
• If the physical states of reactants and products are not given, an uninformed person might try to bring about the reaction by mixing solid KBr with solid AgNO3
• These solids would react very slowly or not at all
• Every compound has a formula which cannot be altered
• A chemical reaction must account for every atom that is used
• Completing and Balancing Chemical Equations

  1. Write correct formulas

  2. Decide type of reaction

  3. Write correct formula(s) for products

  4. Balance the equation
• Types of Chemical Reactions

  • Combination Reactions
  • Decomposition Reaction
  • Displacement Reaction
  • Metathesis (Double Displacement Reaction)
  • Neutralization Reaction
  • Combustion Reaction
• Combination Reactions

  • Two or more substances combine to form one product
• Combination Reaction General Form

  1. A + B

  2. AB
• Combination Reaction Patterns

  • Metal + Nonmetal → Binary compound
  • Nonmetal + oxygen → Nonmetal oxide
  • Metal oxide + water → Metal hydroxide
  • Nonmetal oxide + H2O → Oxyacid
  • Metal oxide + Nonmetal oxide → Salt
• Decomposition Reaction


  • A compound decomposes to form two or more substances
• Decomposition Reaction General Form

  AB → A + B
• Decomposition Reaction Patterns

  • Hydrates → Salt + Water
  • IA bicarbonates → Carbonates + H2O + CO2
  • IIA bicarbonates → Metal oxide + H2O + CO2
  • Carbonates → Metal oxide + CO2
  • Chlorates → Chloride + Oxygen
  • Metal oxide → Metal + Oxygen
  • H2O → H2 + O2