Enzyme Catalysis

Purpose:

In the experiment the purpose was to determine the rate at which a 1.5% H2O2 solution decomposes when catalyzed by the purified catalase extract.

Intro:

In the experiment enzymes play a huge role because they are also known as catalysts. A catalyst affects the rate of a chemical reaction. An enzyme-catalyst reaction occurs when the substrate attaches to the active site of the enzyme, which then causes the reaction. The more time that the enzyme has to catalyze the substrate the less of the 1.5% H2O2 solution will be used.

2B : To begin the experiment we added 10 mL of 1.5% H2O2 into a cup. Then we added 1 mL of H2O, 10 mL of H2SO4 and proceeded to mix it. Then we removed a  5 mL sample and put it into a different cup. After that we used a burette to add one drop at a time of KMnO4 to the solution. After each drop we swirled the solution until the pink or brown color remained.  We ended up getting a baseline of four after putting potassium permanganate into our solution.  Originally, we had four mL of hydrogen peroxide but it took four mL of potassium permanganate to keep the substance at a pink shade making us have a total of 8mL now.  We subtracted the amount we have now to what we started with to get our baseline of four. We put the sulfur in our solution in order to stop the enzymes from catalyzing anymore.  The pH of sulfur is too low for an enzyme to function in and ends up resulting in a denatured enzyme.  Our baseline could have been less considering we were not careful with the amount of potassium permanganate we put into our solution. This could have resulted in an excess amount of potassium permanganate.   

Solution after sulfur was added

2C:

After leaving our solution overnight, we found that 3.5 mL of hydrogen peroxide had been catalyzed.  This means that a total of 12.5% of the solution was catalyzed overnight.  This could have been altered by our setting of the room however.  The temperature of the room could have made it harder for the hydrogen peroxide to catalyze as it may not have been in its optimal temperature.   

2D:

After performing this experiment, our results ended up all over the place.  The amount of hydrogen peroxide was catalyzed using varied  time intervals.  At times, we received a positive result and at others a negative.  However, there was no pattern to our data.  This could be because of the way we handled the potassium permanganate in an uncontrolled manner.  Instead of carefully adding drop after drop, we let a stream flow into our beaker perhaps resulting in an excess of potassium permanganate.  We should have noticed that as the time interval increased, the amount of hydrogen peroxide used increased as well.  This is because the enzyme should have catalyzed the hydrogen peroxide into water and oxygen gas.  As the time increased, the enzyme had more time to do this.   

Hydrogen peroxide before potassium permanganate was added.