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 Methods 2 POTATO / KNIFE / ICE BATH WITH Ice TABLE SALT (Na Cl) 6-10 gram so 1% HYDROGEN PEROXIDE / Distilled Water (200 ml each) o 1-1000 ml BEAKER / 8-SMALL BEAKERS (40 ml) o 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. RESULT SAt 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 grams, again decreased the oxygen displacement at 30 seconds by 5 ml.
At 60 seconds the decreased change was at 6 ml. 90 second mark changed the displacement by 7 ml. and the 120 second mark decreased the oxygen to 10 ml. The final beaker (#4) with 3 grams of sodium chloride surprisingly increased the oxygen displacement at 30 seconds by 1 ml.
At 60 seconds and 90 seconds marks the oxygen raised 2 ml. each. The 120 seconds mark the oxygen increased by 1 ml. This surprised outcome will be explained furthermore in the discussion section. To summarize, the average decreased oxygen displacement between Beaker#1 with no sodium chloride and Beaker#2 with 1 gram of sodium chloride was 9. 75 ml.
between 30 seconds and 120 seconds. The oxygen displacement average between Beaker#2 with 1 gram of sodium chloride and Beaker#3 with 2 grams of sodium chloride was 7 ml. of oxygen between 30 seconds and 120 seconds. And lastly the oxygen displacement average difference between Beaker#3 with 2 grams of sodium chloride and Beaker#4 with 3 grams of sodium chloride was 1. 5 ml.
increase of oxygen. The greatest difference of the displacement was between Beaker#1 with no additional sodium chloride and Beaker #2 with 1 gram of sodium chloride. DISCUSSION The results of this experiment revealed and supported my hypothesis that salt concentration (Na Cl) does affect the enzyme activity. The salt concentration affected the behavior of enzymes in couple ways. First, sodium chloride can have an effect on the equilibrium constant for the reaction being catalyzed, which does not occupy the enzyme but does prompt the conclusion of the enzyme activity.
Second, the increased sodium chloride decreased the effect of the enzyme chemistry. If salt concentration is very low as in Beaker#1, the enzyme will bond together and interaction will produce displacement of oxygen due to high rate of reaction. If the salt concentration is high, normal interaction will be blocked and lower levels of oxygen will be the outcome. Extremes of salt concentration can inactivate an enzyme. Salt concentration in every enzyme has a paramount salt concentration in which it can catalyze reaction. Too high too low a salt concentration will denature the enzyme.
Too high concentrate might also have a reversed impact meaning forward and reverse reactions occur as what occurred with Beaker #4. Beaker#4 with 3 grams of sodium chloride definitely surprised us because our assumption was the more sodium chloride equals more displacement of oxygen. To continue with this experiment the things I would do differently is to repeat this whole experiment again if time permitted that way the results would not be biased. Furthermore, I would increase the concentration of the sodium chloride past 3 grams and verify whether the high concentration would provide further reverse reactions possible equilibrium as Beaker#4. CONCLUSION 1.
The displacement of oxygen decreased by at least 5 ml. as 1 gram of Na Cl was added to each solution. 2. Reverse reaction of oxygen displacement would occur if 3 grams of Na Cl is added to the solution..