Investigating the effect of temperature on the rate of reaction of yeast.

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Andy Freeman        Science Coursework        

Investigating the effect of temperature on the rate of reaction of yeast

Introduction

Yeast is a fungus found on the surface of many fruits, including grapes.  It respires the sugars on the fruit, to produce energy for its own needs.  This is called anaerobic respiration.

Glucose        Ethanol + Carbon dioxide

(6C6H1206)        (2C2H5OM + 2CO2)

What I plan to do is have a conical flask with 50cm3 of yeast suspension, 3g of sugar.  This will then react, which will travel down the rubber tube, and into a tub of water.  The bubbles of carbon dioxide, will then come out of the tube, and go inside a measuring cylinder.  I will then be able to measure the amount of carbon dioxide produced.  We will time for 5 Minutes, and then stop.  We will then record the results we get in a table.  The diagram below shows how it is set up:

Plan

The apparatus I will use are:

  • Beaker
  • Conical Flask
  • Thermometer
  • Stop watch
  • Plastic tube
  • Yeast, Sugar and Warm water
  • Rubber Bung & rubber tubes
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The variable of this experiment is going to be the temperature, as this is what I will be changing each time, and the other ingredients will stay the same.

To make the experiment fair, I am going to make sure that I keep the ingredients exactly the same each time I measure out the yeast, sugar and water.  I will also be as close to the set temperature as possible.  This makes sure that the only limiting factor of the investigation will be the temperature.  Although the temperature I use will not stay exactly the same all throughout ...

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