Biology Project

Title To investigate the effect of temperature on enzymes activity in a solution with washing powder.

Why we conduct this experiment? One day,when we were watching TV,we saw a commercial of a washing powder. The company claims that the enzyme in the washing powder help washing a lot! As we have learnt before that temperature affects the activity of enzyme. We want to know that will temperature affect the washing effect of the powder

Principle 1) Temperature 2) Ions in the solution vibrate faster 3) Frequency of collision 4) Chance of forming the enzymes-substrate complex Therefore, rate of reaction on the removal of milk increases as temperature increases. By measuring the amount of light absorbance by the solution, we can know how much chocolate milk has gone to the solution.

Principle Temperature is too high enzymes will be denatured preventing the forming of enzyme-substrate complex. Temperature is too low enzymes will be inactive rate of reaction stays low

Apparatus Computer x 1 Calorimeter x 1 Boiling tube x 10 Beakers x 5 Measuring cylinder x 2 Lighter x 1 2x2cm 3 cloth x 10 Forceps x 1 Bunsen Burner x 1 Stop-watch x 1 Electronic balance x 1 Stirrer x 1 A pack of Washing powder Thermometer x 5 A pack of chocolate milk

Preparation for the control solution 1. Weigh 0.2g of washing powder by using electronic balance and dissolve them into 120 cm 3 of water. 2. Then, boil the solution to denature the enzymes in the washing powder. 3. Measure 20 cm 3 of solution to each of the hive boiling tubes.

Preparation for the experimental set up 1. Weigh 0.2g of washing powder by using electronic balance and dissolve them into 20 cm 3 of water for each test tube

Preparation for the colorimeter 1. Connect the colorimeter to the computer. 2. Calibrate the colorimeter by distilled water. Preparation of cloth with chocolate milk 1. Cut 10 pieces of 2 cm*2 cm cloth, then soaked them into chocolate milk 2. Dry the cloth thoroughly.

Preparation for the water bath 1.Prepare water bath of 0 ∘ C, Room temperature, 45 ∘ C, 70 ∘ C, 90 ∘ C by mixing hot water with ice.

Set up 1. Put one boiling tube with enzymes and one with denatured enzymes into a water bath of 0 ∘ C. 2. Wait until the solution obtains the temperature of that of the water bath. 3. Measure the initial colour intensity of the solution of the experiment one and the control one by using the colorimeter.

4. Put the cloth in the tubes for 90 seconds. 5. Take the cloth out with a forceps and shake the solution inside the tubes gently. 6. Measure the final colour intensity of the solution. 7. Repeat the experiment in different temperature of water bath

Result

Discussion color absorbance in the y-axis = amount of dirt being removed = the degree of effectiveness of the washing powder (3 0 C to 45 0 C ) the washing ability of the cleaning powder with enzyme is higher than that without enzymes.

Discussion Cleaning ability of the washing powder is enhanced by the enzymes reaction. The washing powder is most effective at 45 0 C = optimum temperature of the enzymes. Effectiveness remains nearly the same in both graphs from 75 0 C onwards because the enzymes has been denatured.

Conclusion As temperature increase,the enzymes activity of the washing powder increases. Thus the washing power is greater. As we see from the result that without enzyme,the washing power still increase with temperature. there are other factors affecting the washing power.And the enzymes only speed up the reaction.

Errors: The degree of dissolution of the washing powder may be different in different temperature. Some of the chocolate milk in the cloth was being squeezed out when the cloth was removed by the forceps. Some water evaporates during denaturation of the enzymes

Errors: The enzymes in the washing powder are not evenly distributed. Improvement: Larger amount of washing powder solution should be used.

Errors: For the two tubes in 0 ∘ C, water vapour blurred the container of the colorimeter when taking the reading. Improvement: Place the container with low temperature in the environment so that the vapour will not condense on the surface

Errors: The temperature cannot be keep constant throughout the experiment. Improvement: We cannot found any suggestion for improvement.

Group members: Margaret Chung (11) Janice Mok (17) Reiko Tse (22) Connie Wong (25) Emily Yum (31)