Реферат: Fermentation Essay Research Paper AimsAim 1To find

Kinetic Theory

The kinetic theory is a theory, which emphasises on pressure, volume and temperature. It states that gases contain particles that are always moving. Gases then exert pressure because their particles are colliding with the wall of the container. If the volume of the gas is decreased, then the particles would hit the wall more often and the pressure would increase.

When a lump of dough, which contains air and carbon dioxide, is heated in the oven, the volumes of the gases increase, resulting in the bread rising. This process can be shown by this word equation: Increase in temperature Volume increases (Gas expands) This is because as the temperature of the gas increases, the particles get more energy. This causes the particles to move faster and collide with each other and the walls of the container. If the gas cannot expand, the pressure would increase. If the pressure is kept constant while the temperature is increased, then the gas will expand. Prediction

I predict that as the temperature increases, the dough will rise more quickly. The effect of the temperature upon the rate of reaction can be predicted by using the collision theory. The theory states that the molecules of glucose must break its bonds to form atoms of carbon dioxide, hydrogen and oxygen and then rejoin to form molecules of ethanol (carbon dioxide, oxygen and hydrogen) and carbon dioxide. However, before the atoms of carbon dioxide, hydrogen and oxygen join together, they must collide with each other. A fixed amount of energy must be reached if the products are to form. If the collisions produce enough energy (collide fast and in the right direction) a reaction would take place. Not all collisions would result in a reaction.

I predict that increasing the temperature would speed up the reaction. This is because when the mixture of glucose and yeast is heated, the molecules would gain energy and move faster and travel a greater distance, which would result in more collisions. Also, the particles are moving faster therefore a large proportion of the collisions would exceed the activation energy, thus speeding the rate of reaction.

I also predict that by doubling the concentration of zymase would double the reaction. Increasing the concentration means that there are more enzymes in a given space, therefore more active sites would be available for a reaction to take place in. Larger quantities of the substrate would enter the active sites, resulting in an increased rate of reaction. I predict that the dough would rise the most at 40ºc because the enzymes consist of protein which work best at body temperature. If the temperature is too high, then the enzymes will not be able to hold the reactant and eventually burst. We say that the enzyme will ‘denature’. At low temperature, the enzymes would be inactivated so the reaction would not take place. I think that 40âC would be the ‘optimum temperature’ because I believe that the reaction would show maximum catalytic activity at that temperature. ApparatusBeakerMeasuring Measuring

cylinder (small)cylinder (large)Filter paperSafety matStirring rod

StopwatchThermometer Bunsen burner10g flour2.5g sugar20cm of yeastWeighing scales Diagram

Method 1.Weigh out 2.5 grams of sugar onto filter paper. Add to beaker.

2.Weigh out 10 grams of flour onto filter paper. Add to beaker.

3.Measure 20cm of yeast in a small measuring cylinder. Stir and add to beaker.

4.Freeze mixture to 0âC.

5.Stir dough and add to the bottom of the large measuring cylinder, making sure it does not touch the sides.

6.Note volume of mixture at zero minutes and then record volumes of mixture every one-minute for twenty minutes.

7.Repeat experiment three times.

8.Change temperature of the mixture to 20âC and do experiment three times.

9.Change temperature of mixture to 40âC and do experiment three times.

10.Change temperature of mixture to 60âC and do experiment three times.

11.Change temperature of mixture to 80âC and do experiment three times.

12.Change temperature of the mixture to 100âC and do experiment three times.

13.Put away equipment. Safety

·Wear safety goggles.

·Be careful of hot water.

·Use safety mat.

·Handle hot beaker with care.

·Beware of cold water. Fair Testing

·Increased temperature of mixture by 20âC each time to get good range of results.

·Measured volume of mixture every minute from zero to twenty minutes to get good range of results.

·Did each experiment three times to get average volume of mixture.