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An experiment to measure the volume of oxygen produced with Hydrogen Peroxide and Celery Catalyse reacting at varying temperatures.

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Introduction

#Chemistry Coursework Title: An experiment to measure the volume of oxygen produced with Hydrogen Peroxide and Celery Catalyse reacting at varying temperatures. Aim: The aim of this experiment is to find out how different temperatures of hydrogen peroxide and catalyse will affect the volume of oxygen produced. Diagram Variables: Independent Variable: Temperature Dependant Variable: Volume of Oxygen produced. Control Variables: Light, concentration, volume of hydrogen peroxide and catalyse solution, apparatus, pH, To ensure this experiment is carried out fairly we will use sensible measuring cylinders (i.e. if the measurement is 10cm3 then we will use a 10cm3 cylinder). Also we will use the same person for timing and measuring this will accuracy. A control I will carry out is by doing my experiment at room temperature. Prediction I predict that the more catalyse used will speed up the reaction rate between the catalyse and hydrogen peroxide. On a graph, as the temperature of hydrogen peroxide and the catalyse is increased the rate of reaction will increase forming a series of positively correlated lines, increasing in gradient as the hydrogen peroxide and the catalyse temperature increases. The optimum temperature will be about 35�C. On a graph, the rate of reaction will be directly proportional to the temperature of each hydrogen peroxide and catalyse sample, producing a positively correlated scatter graph with a line of best fit, however after a certain temperature about 40�C the enzymes will denature and the rate of reaction will slow down and soon stop this. The particular enzymes in question are breaking enzymes and they will engulf the substrate and separate it into smaller pieces and release it. The enzymes will not die or be used up and will continue working until all the substrate is reacted with. Predicted Graph Justification of prediction The lock and key hypothesis Enzymes are biological catalysts usually a protein made in living cells. This means that they speed up the chemical reactions in living things. Enzymes are large molecules with hundreds of amino acids. ...read more.

Middle

Thermometer this will measure the temperature of the two reactants; hence the experiment can be carried out at the desired temperature. Temperature (?C) Oxygen produced(cm3)- 1st Attempt Oxygen produced(cm3)- 2nd Attempt Oxygen produced(cm3)- 3rd Attempt Average 10�C 22�C 30�C 35�C 40�C 50�C 60�C 70�C Results Reliability To make my experiment reliable we are going to have only one of us to do measuring and timing. Also we will take care when assembling the equipment this will ensure there are no leaks or other errors. We will also use suitable measuring equipment and by measuring carefully and correctly we will get reliable measurements which will ensure reliable results. The reason for using suitable equipment is because if measuring 10cm3 of liquid and we use a 100cm3 measuring cylinder, even if we read the measurement accurately the cylinder is only accurate to 1 cm3 whereas if we use suitable equipment ( 10cm3 cylinder) it will be fives times more precise hence would give a reading within 0.2 cm3. By taking three readings of each concentration it will be easier to identify anomalies. Finally we will measure all our liquids from the bottom of the meniscus. Changes to Method We had to make changes to our method which may have made our experiment less accurate. Instead of using a gas syringe we used an upturned measuring cylinder as there were not enough for each pair to have one. Also instead of putting only two celery and hydrogen peroxide test tubes in the water bath we put six. This made the experiment efficient and more reliable. Processing Data In order to process our data we measured the gas produce by using the values on the measuring cylinder at the bottom of the meniscus. We pencilled in these values into a blank results table. After completing all three attempts we worked the average by adding all three attempts at each temperature and dividing by three. ...read more.

Conclusion

Looking at the graphs and results there is a clear indication that there is a variation around the optimum temperature. As I did not know the exact optimum temperature before I did the experiment I could only estimate what it could be and this is why I chose to do these temperatures as they gave us a rough idea of the optimum temperature. Therefore on the graph there is a variation around the mean. In future I could do more temperatures i.e. 360c, 370c, 380c etc. This we give us less variation and provide me with a more conclusive optimum temperature. The temperature could be kept more constant by using an electric, thermostatically controlled water bath. This can maintain the temperature to within + or - 0.5C.I could have also used a buffer solution in order to control the pH so it was the same in each experiment as pH affects enzymes and the pH of the mixture may have changed at different temperatures. I could have controlled the pH by adding a set volume of buffer solution every time to the enzyme. I could have made the actual measuring part of my experiment by using a gas syringe controlled by a computer probe; this would make human error very slight. I could have also us I could extend my experiment by investigating how quickly Celery Catalyse is denatured at high temperatures. From my graphs I can see the rate of reaction is greatly decreased at 60-70�C. So I could set up this experiment by having two water baths, in one water bath I would put a test tube to heat to 65�C. Then I would heat hydrogen peroxide in both baths in the same way. Once both solutions had equilibrated I would mix both solutions and measure the volume of gas produced as before. I would do this at different times to see how long catalyse takes to denature. Also I could do my experiment at different temperatures that I didn't try the first time, this would give me more evidence to back up my conclusions. ' By Dipam Patel 4E ...read more.

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