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DESCRIPTIVE TITLE

The Effect of Different Amounts of Sodium Chloride on the displacement of oxygen.

INTRODUCTION

The dependability of the rate of an enzyme-mediated reaction is based on two factors: the substrate concentration and the concentration and action of the enzyme that catalyzes the reaction (Vander, et. al., 2001). Enzymes are catalysts that produce chemical reactions in cells. Enzymes which are large proteins perform a reaction which acts upon a substance known as a substrate. When combined, the substrate bonds to the active site on the enzyme creating an enzyme-substrate complex. It is from this complex that specific products are created.

Sodium Chloride is a compound known commonly as table salt. This compound is used for many things, including food flavoring, a means of preservation and to aid or inhibit a chemical reaction. Saline concentrations have been shown to affect certain enzymes by a process known as denaturing. This process can change the shape of the enzymes active site, possibly minimizing the ability of the substrate to bond to that specific enzyme (Starr and Taggart, 2001).

When specific enzymes are combined with hydrogen peroxide as a substrate, the resulting products are water and oxygen (Mader, Sylvia, 1998). By introducing sodium chloride, the predicted outcome would be the decreased production of oxygen as a product. By denaturing the enzyme, the reaction rate will decrease because sodium chloride will prevent the hydrogen peroxide from binding to the active site on a given number of the enzymes. This decrease in binding will inhibit the production of water as well as oxygen.

MATERIALS AND METHOD

* 2 POTATOS / KNIFE / ICE BATH WITH ICE

* TABLE SALT (NaCl) 6-10 grams

* 1% HYDROGEN PEROXIDE / Distilled Water (200ml each)

* 1-1000ml BEAKER / 8-SMALL BEAKERS (40ml)

* 1-STOPPER / 1- RUBBER HOSE / 1-GAS BOTTLE

* 1-INVERTED GRADUATED CYLINDER / 1-PLASTIC TUBE

* 1-WEIGHT SCALE / 1-WATER PAN / 1-BLENDER

We started by cutting the potato in pieces and weighing them until they weighed at 200 grams. While the potatoes were being done, we filled the blender with 2 handfuls of ice and 200 ml. of cold distilled water. Then we mixed the potato pieces, ice and 200 ml. of cold distilled water for about 15-20 seconds at high speed. I then grabbed the 1000 ml. beaker so I could pour the solution from the blender and place it in the ice bath. Next we took the 4-40 ml. beakers and labeled them A-D. The other 4-40 ml beakers were marked as 1-4. We measured 40 ml. of the potato extract and poured it in each beaker labeled A-D. Next we poured 40 ml. of hydrogen peroxide in each beaker labeled 1-4. The water pan should be filled with tap water or distilled water so we could invert the graduated cylinder so you have captured enough water in the cylinder to conduct the experiment.

The more water captured the better of you are. As we practiced inverting the cylinder, another person prepared the hose by placing one end of the hose underwater in the pan and underneath the cylinder. The other end of the hose was connected through the stopper. Now we were ready to start the trials. We added the hydrogen peroxide first to the gas bottle and made sure that one of us was the time keeper to notify the others of 30

seconds intervals. The other person who is either not as busy has less to do then others should pour the catalyst (potato extract) into the gas bottle and place the rubber stopper on the bottle with the clock starting. The one thing that we remembered was that if we noticed any foam appearing to be in the hose we had to stop and remove the hose, clean out the foam by rinsing it and restarting the experiment from the very beginning.

RESULTS

At the conclusion of the experiment we summarized and calculated our results of the oxygen produced in ml. versus the concentration of the sodium chloride. The first beaker, which did not include any additional sodium chloride provided, other what the hydrogen peroxide and catalyst had already, generated the most significant displacement of oxygen. The second beaker with catalase, hydrogen peroxide and 1 gram of sodium chloride lowered the oxygen output. At the half of minute mark, the oxygen output decreased by 5 ml. 1 minute mark reflected decrease of 10 ml. And at both 90 and 120 seconds marks, the oxygen displacement decreased by 12 ml. each. The third beaker with the sodium chloride at 2