Chemical Reactions

• Alkali


  A type of soluble base
• Common (household) acids and bases / alkalis


  • Battery/sulfuric acid, citric acid, acid rain, stomach/hydrochloric acid, vinegar/ethanoic acid
  • Soap flakes, washing up liquid, cleaning products - oven cleaner
• Common lab acids


  • Hydrochloric acid
  • Sulfuric acid
  • Nitric acid
• Indicator


  A substance that changes colour depending on how acidic or alkaline another substance is
• Indicator examples


  • Red cabbage, litmus, universal indicator, methyl orange, phenolphthalein
• Problem with using litmus paper

  It only shows if something is an acid or base/alkali not the strength
• pH of a strong acid

  pH 1
• pH of washing up liquid

  pH 8/9
• Acid + alkali reaction


  Salt + water
• Neutralisation


  The reaction between an acid and an alkali
• Separating products of acid-alkali reaction

  1. Evaporate off the water to leave crystals of the salt behind (crystallisation)

  2. Allow distil off and collect the water leaving the salt behind
• Salt


  A compound in which the hydrogen in an acid being replaced by a metal
• Metal oxide (base) + acid reaction


  Salt + water
• Other product formed when metal carbonate reacts with acid

  Carbon dioxide
• Salt formed when sodium hydroxide reacts with hydrochloric acid


  • Sodium chloride
• Salt formed when sodium hydroxide reacts with sulfuric acid


  • Sodium sulfate
• Acid to use to make sodium nitrate salt


  Nitric acid
• Atoms are not created or destroyed. They rearrange themselves during a chemical reaction
• Zinc + copper sulfate

  1. zinc sulfate

  2. copper
• Ways to indicate a chemical reaction has taken place


  • Temperature change
  • pH change
  • Bubbling/effervescence/gas given off
  • Colour change
• A new product is always formed in a chemical reaction
• Oxidation


  Type of reaction where magnesium + oxygen -> magnesium oxide
• Physical change


  • Change of state e.g. ice -> water -> steam
  • Iron -> liquid iron -> gaseous iron
• Methane (fuel) + oxygen

  1. Carbon dioxide

  2. Water
• Combustion


  Type of reaction where hydrocarbon + oxygen -> carbon dioxide + water
• Energy is also produced during the combustion reaction
• Rust


  Iron + oxygen -> iron oxide
• Exothermic reaction


  A reaction that transfers heat to the surroundings / gives out heat
• Endothermic reaction


  A reaction that results in a fall in temperature
• Uses of endothermic reactions


  • Sports injury packs
• Magnesium + oxygen


  1. 2 magnesium

  2. 1 oxygen

  3. 2 magnesium oxide
• No mass is lost or gained during a chemical reaction when the reactants turn into products. The total number of atoms is the same.
• 123g of copper carbonate produces 79g of copper oxide and 44g of carbon dioxide
• Thermal decomposition


  When a substance breaks down into at least 2 other substances when heated
• Copper carbonate


  1. Copper oxide

  2. Carbon dioxide
• You would see a colour change (copper carbonate is green, copper oxide is black) to indicate a chemical reaction has taken place
• Metals


  Left side of the periodic table
• Groups of elements

  • Group 1 - Alkali metals
  • In between group 2 & 3 - Transition metals
  • Group 7 - Halogens
  • Group 0 - Noble gases
• Properties of metals


  • Good conductors of energy
  • Good conductors of electricity
  • Strong & tough
  • Shiny
  • Sonorous
  • Malleable
  • Ductile
  • High melting and boiling points
  • High densities
  • Can make alloys
  • Magnetic
• Property of metals

  Use and how it links to the property