Chemistry AS 3

• Deflection of a stream of liquid from a burette

  Indicates polarity or lack of polarity within a molecule
• Molecules are non-polar if they do not contain polar bonds
• Non-polar molecules which are liquids will not be deflected by a charged rod
• Some molecules which contain polar bonds are non-polar if the polar bonds are arranged symmetrically
• Molecules which contain polar bonds which are not arranged symmetrically are polar
• Polar molecules which are liquids will be deflected by a charged rod
• Procedure


  1. Fill a burette with one of the liquids provided

  2. Place an empty 250 cm³ beaker under the burette to collect the jet of liquid

  3. Charge the plastic rod/ruler by rubbing it vigorously with a piece of dry cloth

  4. Open the burette tap so that a jet of liquid flows into the beaker. Bring the plastic rod/ruler towards the jet but do not let them touch. Record which liquids are deflected and identify the liquid which is deflected the most
• Liquids tested


  • Water
  • Propanone
  • Ethanol
  • Cyclohexane
  • Methylbenzene
• The liquids which showed deflection when a charged rod was brought near them are water, propanone and ethanol
• The results displayed the greatest deflection secured for water suggesting it's the most polar liquid
• Electrical conductivity


  Substances will conduct electricity if they contain charge carriers, such as ions or electrons, that can move
• Apparatus and materials


  • safety goggles
  • direct current 6 V power supply
  • bulb
  • crocodile clips
  • graphite rods
  • electrical wires
  • 100 cm³ beaker
  • glass rod
  • spatula
  • 50 cm³ measuring cylinder
  • bottle of deionised water
  • Bunsen burner
  • tripod
  • gauze
  • heat mat
  • evaporating basin
  • sodium chloride
  • sucrose
• Procedure for testing electrical conductivity

  1. Place four spatula measures of sodium chloride into a 100 cm³ beaker

  2. Set up a circuit with the electrodes dipped into the sodium chloride, ensuring they don't touch

  3. Switch on the power pack and record observations

  4. Measure 40 cm³ of deionised water, add to the beaker and stir to dissolve

  5. Dip the electrodes into the aqueous solution of sodium chloride and switch on the power pack

  6. Repeat the experiment using sucrose
• Observations on electrical conductivity

  • Solid sodium chloride: bulb doesn't light
  • Aqueous sodium chloride solution: bulb lights
  • Solid sucrose: bulb doesn't light
  • Aqueous sucrose solution: bulb doesn't light
• Solubility


  Chlorine, bromine and iodine have low solubilities in water; they are much more soluble in non-polar solvents such as hexane
• Iodine is the least soluble of the halogens in water, iodine solution is usually iodine dissolved in potassium iodide solution
• Apparatus and materials


  • safety goggles
  • test tubes and a test tube rack
  • boiling tube
  • stoppers/rubber bung
  • plastic dropping pipettes
  • chlorine water
  • bromine water
  • iodine solution
  • hexane
• Procedure for determining solubility of halogens


  1. Place 3 cm³ of each aqueous halogen solution into separate test tubes

  2. Place 3 cm³ of hexane into each test tube

  3. Stopper each tube and shake the mixture

  4. Allow the two layers to settle and observe the colour of the upper layer
• Observations on solubility


  • Chlorine: orange aqueous, yellow-brown in hexane
  • Bromine: red-orange aqueous, brown in hexane
  • Iodine: purple-pink aqueous, violet-purple in hexane
• Reactivity of halogens


  The reactivity of the halogens decreases down the group. This can be demonstrated using displacement reactions.
• Apparatus and materials


  • safety goggles
  • test tubes and a test tube rack or spotting tile
  • plastic dropping pipettes
  • chlorine water
  • bromine water
  • iodine solution
  • potassium chloride solution
  • potassium bromide solution
  • potassium iodide solution
  • hexane
  • deionised/distilled water
• Procedure for determining reactivity order of halogens


  1. Add 1 cm³ of each aqueous halogen solution into separate test tubes

  2. Add 1 cm³ of potassium chloride solution and record any colour change

  3. Repeat with potassium bromide and potassium iodide solutions, adding 1 cm³ of hexane when using potassium iodide
• Halides as reducing agents

  The halogens can act as oxidising agents. The halide ions can therefore act as reducing agents and can be oxidised back to the halogen. The halides' reducing ability increases down the group.
• Apparatus and materials


  • safety goggles
  • test tubes and a test tube rack
  • plastic dropping pipette
  • spatula
  • glass rod
  • filter paper
  • concentrated sulfuric acid
  • concentrated phosphoric acid
  • potassium chloride
  • potassium bromide
  • potassium iodide
  • concentrated ammonia solution
  • acidified potassium dichromate(VI) solution
  • universal indicator paper
  • deionised water
• Procedure for reactions of halides with concentrated acids

  1. Place a spatula measure of potassium chloride in a test tube

  2. Add a few drops of concentrated sulfuric acid and record observations

  3. Test the gas evolved with damp universal indicator paper and a rod dipped in concentrated ammonia solution

  4. Repeat the experiment with potassium bromide and potassium iodide, testing the gases with additional tests

  5. Repeat the experiment using concentrated phosphoric acid instead of sulfuric acid
• Observations on reactions of halides with concentrated acids

  • Potassium chloride with sulfuric acid: misty fumes formed
  • Potassium chloride with phosphoric acid: misty fumes formed
  • Potassium bromide with sulfuric acid: red-brown vapour produced
  • Potassium bromide with phosphoric acid: grey-black solid formed
  • Potassium iodide with sulfuric acid: purple vapour produced
  • Potassium iodide with phosphoric acid: yellow solid produced
• Qualitative tests


  Chemical tests used to identify unknown substances
• Procedure for testing for metal ions

  1. Dip a nichrome wire in concentrated hydrochloric acid

  2. Dip the wire into the solid metal chloride

  3. Hold the wire in the blue Bunsen flame and note the colour of the flame
• Observations on metal ion tests

  • Lithium chloride: crimson flame
  • Sodium chloride: yellow flame
  • Potassium chloride: violet flame
  • Calcium chloride: brick-red flame
  • Copper(II) chloride: blue-green flame
• Procedure for testing for halide ions


  1. Dissolve a spatula measure of potassium halide in dilute nitric acid

  2. Add silver nitrate solution and record observations

  3. Add dilute ammonia solution and record observations

  4. Add excess dilute ammonia solution and record observations

  5. Repeat using concentrated ammonia if precipitate remains
• Procedure for testing for sulfate ions


  1. Dissolve a spatula measure of sodium sulfate in deionised water

  2. Add barium chloride solution and record observations
• Procedure for testing for carbonate/hydrogencarbonate ions

  1. Add dilute nitric acid to a test tube

  2. Add sodium hydrogencarbonate and bubble any gas produced through limewater
• Procedure for testing for ammonium ions

  1. Add sodium hydroxide solution to a test tube

  2. Add ammonium chloride and warm gently

  3. Test any gas evolved with damp universal indicator paper and a glass rod dipped in concentrated hydrochloric acid
• Procedure for testing for iodine

  1. Add iodine solution to a test tube

  2. Add a few drops of starch solution and shake gently
• Unsaturated hydrocarbons


  Contain at least one carbon-carbon double bond or carbon-carbon triple bond
• Bromine water


  • Yellow/orange/brown in colour
  • Reacts with unsaturated hydrocarbons to become colourless
• Test for unsaturation using bromine water


  1. Add 2-3 cm³ of cyclohexene to a test tube

  2. Add 2-3 cm³ of bromine water to the test tube

  3. Shake the test tube gently and record observations
• Bromine water reacts with unsaturated hydrocarbons and the colour changes to colourless
• Halogenoalkanes


  Organic compounds containing a halogen atom (e.g. Cl, Br, I) attached to an alkyl group
• Prepare a halogenoalkane using the techniques of refluxing, separating with a funnel, removing acidity, drying and distillation


  1. Weigh 10 g of sodium bromide and add to the pear-shaped flask

  2. Measure 7.5 cm³ of butan-1-ol and 10 cm³ of water and add to the pear-shaped flask

  3. Slowly add 10 cm³ of concentrated sulfuric acid dropwise while swirling the flask

  4. Add anti-bumping granules and heat the mixture under reflux for 30 minutes

  5. Rearrange the apparatus for distillation and distil off the crude product between 100-104 °C

  6. Transfer the distillate to a separating funnel, add concentrated hydrochloric acid, shake and separate the layers

  7. Add sodium hydrogencarbonate solution to the organic layer, shake and separate the layers

  8. Add anhydrous sodium sulfate to the organic layer to dry it

  9. Distil the dried 1-bromobutane and collect between 101-103 °C, then weigh the product