I will use a pair of electric scales, set to two decimal places, to make sure my results are reliable. I will also make sure there are no bubbles in the measuring cylinder; this could cause more volume of gas than there should be. Other factors like making the temperature exact or the results could be anomalous. Accurate reading will be hard, but I decided to measure the results to the top of the meniscus.
To stay safe I will tuck my tie in, take off my blazer and wear safety glasses. I must also remember to follow all the usual lab rules such as: no eating, no running, listen to instructions, etc.
I predict that when I increase the temperature the amount of carbon dioxide will increase to a certain point. After a certain temperature it will stop reacting because it will be too hot and it will kill off all of the yeast.
To make sure this would be the best experiment I decided to do some preliminary experiments. I have included the results for these:
(1g yeast, 1g sugar at room temperature)
(1g yeast, 1g sugar at 60°C)
(1g yeast, 1g sugar at 37°C)
Next I decided t see how sugar would affect these results. I predict that as I increase the amount of sugar, the amount of reaction will increase too. I included results for this as well:
(1g yeast, 2g sugar at room temperature)
I decided this gave me better results than temperature so I changed my method.
I am going to see the effects of amount of sugar over how much carbon dioxide is released. I will measure it at room temperature (22°C) and use the following amounts of sugar: 1g, 2g, 3g, 4g, and 5g. I have chosen these to give me a range of results. I will take three sets of results and also do two repeats. To keep it fair I must not change the amount of yeast or the temperature.
I will put an inverted measuring cylinder into a trough filled with water and clamp it in place. I will put 10ml of water, 1g of yeast and my sugar into a conical flask connected to the beaker using a delivery tube. I will measure the amount of carbon dioxide given off every 30 seconds for two and a half minutes.
I predict that as I increase the amount of sugar the amount of gas released will increase until a certain point, and then either all of the sugar or all of the yeast is used up. This uses the collision theory. Basically once the yeast has totally reacted there won’t be anything left to react with, so the reaction will stop. The same applies with yeast. This is an example of the lock and key theory using enzymes. The enzymes will ‘die out’ at a certain temperature because the enzymes are adapted to live in a certain part of a living organism, where they work. Enzymes have special ‘holes’ where only a certain molecule will fit; these holes are called active sites because this is where the reaction takes place. The substance it breaks down is called a substrate and is broken up to create a product and sometimes two substrates create one product. The reason the rate of reaction goes down is because the molecules get damaged or used up and become unusable.
I will use the following equipment:
- Measuring Cylinders.
- Conical Flask.
- Delivery Tube.
- Trough.
- Spatula.
- Water Bath (for preliminary only).
- Thermometer.
- Water.
- Dried Yeast.
- Granulated sugar.
- Electronic Scales.
