Topic 1: Stoiciometric Relationships

• Matter


  • Made up of particles – atoms, molecules, or ions
  • Particles are in constant motion
  • Has a mass
  • Occupies a volume in space
• Changes of state


  1. Melting

  2. Boiling

  3. Evaporation

  4. Condensation

  5. Freezing

  6. Sublimation

  7. Deposition
• Melting and boiling are endothermic processes, condensation and freezing are exothermic processes
• Element


  Contains atoms of only one type
• Compound


  Atoms of elements combine in a fixed ratio to form molecules or ions
• Types of matter


  • Elements
  • Compounds
  • Mixtures
• Homogeneous mixture


  Has uniform composition and properties throughout
• Heterogeneous mixture


  Has non-uniform composition and varying properties
• Chemical symbols and equations are a universal language that requires no translation
• IUPAC develops and monitors a system of standardized nomenclature for organic and inorganic compounds
• Homogeneous mixture


  Has both uniform composition and properties throughout, e.g. salt water, metal alloys
• Heterogeneous mixture


  Has non-uniform composition and varying properties, e.g. salad dressing, paint, garden soil
• Element


  Made up of atoms that each have the same atomic number, e.g. lead, Pb, mercury, Hg, bromine, Br
• Compound


  Made up of a combination of atoms or ions in a fixed ratio and having different properties from the constituent elements, e.g. water, H2O, carbon dioxide, CO2, sodium chloride, NaCl
• Pure substance


  Has a definite and constant composition
• Proust's law of definite composition (1806) stated that compounds have distinct properties and the same elemental composition by mass
• An ion is a charged species. Anions are negatively charged and cations are positively charged
• Common polyatomic ions


  • ammonium ion, NH4+
  • phosphate(V) ion, PO4^3-
  • carbonate ion, CO3^2-
  • phosphonate ion, PO3^3-
  • hydrogencarbonate ion, HCO3-
  • sulfate(VI) ion, SO4^2-
  • hydroxide ion, OH-
  • sulfate(IV) ion, SO3^2-
  • nitrate(V) ion, NO3-
  • ethanedioate ion, C2O4^2-
  • nitrate(III) ion, NO2-
  • peroxide ion, O2^2-
• Common acids


  • hydrochloric acid, HCl
  • nitric(V) acid, HNO3
  • phosphoric(V) acid, H3PO4
  • sulfuric(VI) acid, H2SO4
  • ethanoic acid, CH3COOH
• A reaction may be described in terms of starting materials and products. The process of transforming these words into a balanced chemical equation starts with the construction of chemical formulae
• Naming anions


  • -ide
  • -ate
  • -ate
• How to balance chemical equations

  1. Step 1: Balance the metallic element

  2. Step 2: Balance any elements that occur in only one formula

  3. Step 3: Balance the remaining elements if necessary
• Butane, C4H10 is mixed with other hydrocarbons such as propane to create the fuel liquefied petroleum gas (LPG)
• Methylpropane (also called isobutane) is an isomer of butane and is used as a refrigerant, replacing the CFCs that were previously used for this purpose
• CFCs undergo reactions with the ozone in the stratosphere, causing it to break down, leading to the 'ozone hole'
• Types of chemical reactions

  • Combination or synthesis reactions
  • Decomposition reactions
  • Single displacement reactions
  • Double displacement reactions
• The combustion of butane is an exothermic reaction
• Balancing the equation for the combustion of butane

  1. Step 1: Balance the carbon atoms

  2. Step 2: Balance the hydrogen atoms

  3. Step 3: Balance the oxygen atoms
• Atom economy


  Looks at the level of efficiency of chemical reactions by comparing the molecular mass of atoms in the reactants with the molecular mass of useful compounds
• The atom economy is important in the discussion of Green Chemistry
• Atom economy


  Measure of the efficiency of chemical reactions by comparing the molecular mass of atoms in the reactants with the molecular mass of useful compounds
• Atom economy is important in the discussion of Green Chemistry
• In an ideal chemical process the amount of reactants = amounts of products produced. So an atom economy of 100% would suggest that no atoms are wasted
• Nucleophilic substitution reaction


  CH3(CH2)3OH + NaBr + H2SO4 → CH3(CH2)3Br + H2O + NaHSO4
• SO3(g) + H2O(l) → H2SO4(aq)
• NCl3(g) → N2(g) + Cl2(g)
• CH4(g) + O2(g) → CO2(g) + H2O(g)
• Al(s) + O2(g) → Al2O3(s)
• KClO3(s) → KCl(s) + O2(g)
• C3H8(g) + O2(g) → CO2(g) + H2O(g)