RP5 - the effect of pH on the rate of reaction

• What does amylase break down?

  Starch into maltose
• how can we easily detect starch?

  using iodine solution - turns from browny-orange to blue-black
• what is the first step when investigating how pH affects amylase activity?

  put a drop of iodine solution into every well of a spotting tile
• what should you do after putting iodine in the spotting tile?

  place a Bunsen burner on a heat-proof mat and a tripod and gauze over it
• what should you do after setting up the Bunsen burner?

  put a beaker of water on top of the tripod and heat the water until it is 35 degrees (using a thermometer) - try to keep the water constant throughout the whole experiment
• what should you do after heating the water?

  use a syringe to add 1cm$^3$of a buffer solution with a pH of 5 to a boiling tube - use test tube holders to put the tube into the beaker of water and wait five minutes
• what should you do after waiting for five minutes?

  use a different syringe to add 5cm$^3$of a starch solution to the boiling tube
• what should you do after putting the starch solution in the boiling tube?

  immediately mix the contents of the boiling tube and start a stop clock
• what should you do to record how long it takes for the amylase to break down all of the starch?

  use continuous sampling - use a dropping pipette to take a fresh sample from the boiling tube every 30 seconds and put a drop into a well in the spotting tile
• when do you know starch is no longer present?

  when the iodine solution remains browny - orange