chemistry

• Producing hydrated zinc nitrate crystals

  1. Pour 50 cm3 of dilute nitric acid into a beaker

  2. Add a spatula of zinc powder to the acid

  3. Add more zinc until it is in excess

  4. Filter the mixture

  5. Obtain crystals of zinc nitrate from the filtrate

  
• Filtering the mixture


  To separate the solid zinc nitrate crystals from the liquid

  
• Obtaining pure, dry hydrated zinc nitrate crystals

  1. Filter the mixture

  2. Evaporate the filtrate to obtain the crystals

  3. Dry the crystals

  
• Equation for the formation of hydrated zinc nitrate

  
• Bromine


  Liquid at room temperature
• Solid iodine


  Dark purple
• Test for chlorine gas

  1. Damp litmus paper turns red

  2. Bleaches damp litmus paper
• Comparing reactivity of chlorine and iodine

  1. Add chlorine solution to sodium iodide solution

  2. Observe colour change (chlorine is more reactive than iodine)

  
• Limewater changes appearance during combustion of liquid hydrocarbons


  Limewater turns cloudy/milky
• Mass of pure water collected is less than 2.16 g
• Physical test to show water is pure

  1. Water boils at 100°C

  2. Water freezes at 0°C

  
• Process that occurs when a crystal of substance X is added to water

  Dissolution (X(s) → X(aq))

  
• Substance X is a soluble ionic compound
• Stirring the mixture helps dissolve the ammonium nitrate
• Initial temperature of water = 20.0°C, minimum temperature of solution = 16.1°C

  
• Test to show ammonium ions are present

  Add sodium hydroxide solution, observe release of ammonia gas
• Dissolving anhydrous copper(II) sulfate in water is an endothermic process
• The Group 1 metal that reacts faster than sodium and produces a lilac flame is lithium
• Repeating heating and cooling steps until mass is constant ensures all water is removed from the hydrated barium chloride
• Symbol Δ


  Represents heating
• Using hydrated copper(II) sulfate to show a liquid contains water


  1. Heat the hydrated compound

  2. Observe water vapour being produced

  
• Identifying an unknown iron compound

  1. Add sodium hydroxide solution, observe colour of precipitate

  2. Add dilute hydrochloric acid, observe colour change

  3. Test with litmus paper

  
• Litmus turns red in the acidic solution of iron(III) chloride
• The ion that causes the acidic solution is Fe3+
• Test for oxygen is a glowing splint relights
• Identifying unknown salt solutions

  1. Add sodium hydroxide solution, observe colour of precipitate

  2. Add dilute hydrochloric acid, observe colour change

  3. Test with litmus paper

  
• Calcium nitrate decomposition


  1. Calcium nitrate

  2. Decompose when heated

  
• Colourless salt solutions


  • Calcium bromide
  • Calcium chloride
  • Sodium chloride
  • Sodium sulfate
• Identifying colourless salt solutions

  Perform a series of tests

  
• Mixing lead(II) nitrate and potassium chloride

  Lead(II) chloride precipitate forms

  
• Investigating precipitate height


  1. Pour 15.0 cm3 potassium chloride

  2. Add 2.0 cm3 lead(II) nitrate

  3. Allow precipitate to settle

  4. Measure precipitate height

  5. Repeat with up to 14.0 cm3 lead(II) nitrate

  
• Anomalous result


  Circled on graph
• Lines of best fit

  • First 4 points
  • Last 3 points
  • Lines cross
• Possible mistakes causing anomalous result
• First line of best fit should pass through origin
• Lithium reaction with water

  • Lithium floats
  • Vigorous reaction
• Methyl orange colour change


  Indicates basic solution
• Testing for lithium carbonate

  Perform tests to identify white powder
• Ionic bonding


  Formed by the electrostatic attraction between oppositely charged ions
• Testing for carbon dioxide

  Add limewater to apparatus