Factors that Affect the Rate of Yeast of Activity

Mr 198.17

Molecular mass of glucose 198.17

- X 20ml = 3.9g = 1 molar

1000

3.9 x 2 = 7.9g › 20ml, 2 molar

My five different temperatures will be 0ºc, room temperature, 30ºc, 40ºc and 50ºc. The first five experiments will be used to see the effect that different temperatures have on the yeast.

We are going to measure the amount of carbon dioxide given off. Ideally we want to measure the quantity of alcohol produced but this would require a hydrometer, which we do not have.

The second set of experiments will see how the results change when molarity of the substrate (glucose) is changed. In these five experiments the temperature will be constant at 40ºc, which is yeast's optimum level. I know this from the research I have previously done. The water in each beaker will also be kept the same, 50ml. The yeast will be kept the same as it was in the first five experiments. The molarities of glucose will be 9.9g, 19.8g, 29.7g, 39.6g and 49.5grams.

Our final five experiments will be a control. We are having these five with 50ml of water, at room temperature and keeping the glucose at 2% molar. The beakers will not have any yeast in them. We are making sure that we do these five to be certain that we keep the investigation as fair as possible and that we have a comparison at the end of our project.

Apparatus

5 beakers/test tubes

Glucose

Yeast

Water bath

Conical flasks

Water

Retort stands

Tom Francis