Chemistry Investigation

Investigate A Factor Which Affects the Rate Of Fermentation Of Yeast

This experiment is investigating one of the factors which affects the rate of fermentation of yeast.

Several factors affect the rate of reaction:

 Increasing the concentration. (See the lock and key theory.) If the substrate (glucose) is increased, then there would be more keys for the locks, therefore an increase in reactant concentration leads to an increase in reaction rate.

 The surface area, the bigger the surface area, the faster the reaction time is, as the reactant can reach more parts.

 The temperature, an increase in temperature leads to an increase in reactant rate. Generally, as the temperature is increased, the particles get more energy, so they bump into one another more, therefore speeding up the reaction time. This is called the collision theory, which I will discuss in greater depth later.

 Whether or not there is a catalyst. A catalyst speeds up the rate of reaction and remains chemically unchanged by the end of the experiment. A catalyst lowers the activation energy. This is the energy needed to start a reaction.

The variable that I have decided to change is the temperature. I have decided to alter the temperature of the yeast and time the amount of carbon dioxide that will be given off at different temperatures. I have decided to time how much carbon dioxide is given off in five minutes.

Throughout the investigation, I will keep the temperature the same as I have specified for each reading. For example, if I am taking a reading in which the temperature must be 5 degrees, I will make sure that the yeast is kept at this temperature. When I am altering the temperature of the yeast, I will place it in a water bath of the specified temperature, which makes the temperature much more accurate. For example, if I heat up the yeast using a Bunsen burner, I could heat it up too much, thereby denaturing the enzymes and ruining the experiment. After the enzymes have been denatured, they can no longer react.

It will also be important not to agitate the solution at all, because this would cause collisions between particles, speeding up the reaction time and making the test unfair.

While doing an experiment such as this, it is vital to be safe at all times. You should stand up at all times, making sure that stools are firmly under desks.