Optimal Alkaline pH Sodium Hydroxide Felicia, Brunette, Shaelyn

Purpose Discover the optimal Alkaline pH of NaOH, in which enzymes would catalyse the reaction best.

Materials Test tube rack Pipette 40 ml beaker Two 100 ml beakers 6 Paper discs Stop watch Tweezers 1.0 M Sodium Hydroxide(NaOH) solution Peroxide(H 2 O 2 ) solution 1% concentration Tap water(H 2 O) Pre-made Potato Puree

Procedure Experiment: 1.Obtain a test tube rack with six test tubes. 2.Label test tubes 1 to 6. 3.Take test tube 1, and add 1ml of 0.1M NaOH solution, using a pipette. 4.Add 9 ml of water to test tube 1, using pipette 5.Add 1 ml of diluted test tube 1 solution to test tube 2, using pipette 6.Add 9 ml of water to test tube 2, using pipette 7..Add 1 ml of diluted test tube 2 solution to test tube 3, using pipette 8.Add 9 ml of water to test tube 3, using pipette 9.Add 1 ml of diluted test tube 3 solution to test tube 4, using pipette 10.Add 9 ml of water to test tube 4, using pipette 11.Add 1 ml of diluted test tube 4 solution to test tube 5, using pipette 12.Add 9 ml of water to test tube 5, using pipette 13.Add 5 ml of peroxide to test tubes 1 to 5 14.Add 10 ml of water to test tube 6, using a pipette (controlled group) 15.Using tweezers, soak paper disc in potato puree for 5 seconds, and place in test tube 1 16.Using a stop watch, measure the time it takes the paper disc to rise back to the top 17.Repeat steps 15 and 16 for test tubes 2 to 6 18.Repeat steps 15 to 17 two more times, to calculate an average time 19.Record paper disc observations in a table 20.Clean up Preparing Solutions: 1.Obtain the potato enzyme prepared by your teacher, and place in 40 ml beaker, using pipette. 2.Place 50 ml of water in a 100 ml beaker, using a pipette. 3.Place 50 ml of H 2 O 2 in another 100 ml beaker, using a pipette 4.Place 5 ml of NaOH in a 40 ml beaker, using a pipette

Observations

Rate of Reaction vs pH

Analysis  Potato puree was used in this experiment due to the fact that it acts like an enzyme. This is useful as it speeds up chemical reactions. The purpose of this lab was to discover the optimal Alkaline pH of NaOH, in which the enzyme would catalyse the reaction best. During the lab performed, 6 test tubes were set up. The first 5 test tubes were filled with diluted basic solutions. From the 1st test tube with a pH of 14 to the 5th with a pH of 8. The 6th test tube was a negative control as it was filled with water. After completing the experiment, the results were obtained and the average time it took for the paper disc to rise up to the top of the test tube was calculated. The results showed that the enzyme worked best at a pH level approximate to 10, seeing as the paper disc in test tube 3 rose at a rate which was indicated by a graph to be the optimal alkaline pH. This proved that pH changes affected the enzyme activity. The 6th test tube did not react because it was a negative control as water’s pH is neutral. This showed that enzyme activity is inhibited by substances of neutral pH. The sources of errors that could have altered the results are as follows; errors in recording time, wrong calculations of the averages and dilution of the enzyme. The time would have changed the optimal pH of the enzyme. Diluting the enzyme would inhibit its ability to catalyse a reaction; the catalyst cannot be consumed in a reaction.