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===Meaning===
Investigate the effect of [[pH]] on the rate of reaction for an [[enzyme]].
===Method===
*[[Independent Variable]] - [[pH]] of the buffered [[pH]] [[solution]].
*[[Dependent Variable]] - Time taken for the colour change to take place.
*[[Control Variable]]s - The temperature of all solutions. The volume of all solutions.
#Place test tubes containing amylase solution, starch solution and a range of [[pH]] buffer solutions from [[pH]] 1-13 in a water bath at a temperature of 25°C and wait until all [[solution]]s reach that temperature.
#Use a pipette to place one drop of Iodine Solution into each depression in a spotting tile.
#Use a clean pipette to place 2cm<sup>3</sup> of each [[pH]] buffer into seperate depressions of the spotting tile, ensuring the pipette is rinsed each time to prevent contamination.
#Use a clean pipette to place 2cm<sup>3</sup> of starch solution into a depression on the spotting tile.
#Time how long it takes for the colour to turn from blue-black to orange.
#Repeat steps 4 and 5 until all [[pH]] buffers have been tested.
#Plot a graph with [[pH]] on the x-axis and time taken on the y-axis.