CHEMISTRY

• temperature change in chemical reactions


  1) measure 25cm3 of hydrochloric acid into a polystyrene cup.

  2) measure and record temp of hydrochloric acid.

  3) measure 5cm3 of sodium hydroxide and add to cup.

  4) quickly put a lid on cup and gently stir the solution with thermometer through hole in lid.

  5) when reading on thermometer stops changing and becomes fairly constant, record temperature.

  6) repeat steps 3 and 4 to add further 5cm3 amounts of sodium hydroxide to cup.

  7) repeat steps 1-6 to ensure reliability.

  8) calculate mean maximum temp reach for each of the sodium hydroxide volumes.
• crystallisation.


  1) measure 20cm3 of sulfuric acid into measuring cylinder and pour into beaker.

  2) heat gently.

  3) add small amounts of insoluble base.

  4) filter using filer paper and funnel to remove excess.

  5) pour solution into evaporating basin.

  6) evaporate solution using water bath until crystals start to form.

  7) leave in cool place for at least 24 hours.
• electrolysis


  1) add about 50cm3 of copper chloride solution to beaker.

  2) add the lid and insert electrodes through holes.

  3) attach crocodile leads to electrode and connect the rods to the DC terminal to power supply.

  4) set power supply to 4V and turn on.

  5) hold litmus paper near positive electrode.

  6) after a few mins turn the supply power off and observe neg electrode.