Investigate the effect of changing the hydrogen peroxide concentration on the rate of reaction of the break down of hydrogen peroxide by catalase.

∙Measuring/ Observing

        In this investigation I am looking to see if the rate of reaction changes. Measuring the total volume of oxygen produced in each experiment will give me a good indication to how much the reaction rate is taking place. So the main measurement I have to make is the volume of oxygen. I will do this by

∙Apparatus

        The apparatus I am going to write down I will use for each change of concentration I do. I equipment I will need for me to receive the most accurate data will be:

        ∙ Distilled water

        ∙ Catalase (yeast)

        ∙ Hydrogen peroxide         

          ∙ Burette and stand

        ∙ 11 * beaker 50cm3

        ∙ 3 * beaker 250cm3

        ∙ Conical flask 250cm3

        ∙ 3 * syringe 5cm3

        ∙ Measuring cylinder 5cm3

        ∙ 4 * thermometers

        ∙ 2 * water containers

        ∙ Delivery tube

        ∙ Stopper

        ∙ Stop clock

        ∙ Marker pen

∙ Pipette

∙ Safety goggles

∙Method

1. Before I do anything I will put my safety goggles on, and will keep them on through out the whole experiment.
2. First I will place all the equipment I will need to use on a tidy bench so I know where everything is when I need it. This will also make things safer.
3. Pour the yeast, hydrogen peroxide and distilled water into the three 250cm3 beakers. Then make sure the beakers are labelled. Place a thermometer is each beaker, to record the temperature and see if it changes at all.
4. Now I have to make up the concentrations of hydrogen peroxide. The 11 50cm3 beakers will hold the 11 different concentrations. This table will show the concentration of each beaker, also will show how much distilled water and hydrogen peroxide will be in each one.

5. I will table all of the beakers with the concentration the hydrogen peroxide so I know which one is which and also number them. To make up the concentrations in the beakers I will use the two 5cm3 syringes. One for hydrogen peroxide and one for distilled water.
6. I am going to need to use each concentration more than once. So I will triple the volume of the hydrogen peroxide and also the distilled water. So instead of but 0cm3 of distilled water, and 5cm3 of hydrogen peroxide in beaker 1, I will triple it so it will be 15cm3 of hydrogen peroxide. I will do this for each beaker.
7. For each change of concentration of hydrogen peroxide I do, I will also need 5cm3 of catalase. I will use a 5cm3-measuring cylinder to get the right volume. To try and make it as exact as possible I will use a pipette I get the volume even closer to 5cm3.
8. The 5cm3 of catalase I measured out I will poor into the 250cm3 conical flask. This is where the reaction of the break down of hydrogen peroxide by catalase is going to take place.
9. I placed the conical flask in a large water container. This is going to be filled with water and have a thermometer in it. This will act as a water bath to try and keep the temperature of the solutions constant.
10. The burette is turned upside down and clicked on to it’s stand, this is where the oxygen produced from the reaction is gong to be collected and record. This is to help me find out how much oxygen is produced in two minutes. (I must make sure the bottom of the burette is closed completely to make sure no oxygen will enter or escape.)
11. The opening of the burette will stand in another container of water. I must make sure the water level is over the top of the opening of the burette or my results will not be reliable. The burette must be filled with water, but again I must make sure the water stops on one of the markers so I can make an exact result of where the starting measurement of the water in the burette will be.
12. A stopper now must be placed on to the conical flask that contains the 5cm3 of catalase. The stopper must be joined to a delivery tube that will go into the container of water and up the burette. This will enable the oxygen produced from the reaction to travel along the delivery tube and up the burette and push the water out giving me a result of how much oxygen is produced.
13. The stopper placed in the conical flask must also have a hole for a 5cm3 syringe to fit in it. This is for the concentration of hydrogen to be mixed with the 5cm3 of catalase. The syringe will measure out 5cm3 0f the 11 different concentrations of hydrogen peroxide from the beakers.
14. The syringe will now be placed in the small hole containing the different concentrations of hydrogen peroxide. I will set the stop clock for two minutes, record where the starting measurement of the water in the burette is, make sure everything is in the right place. Then is will squirt the 5ml3 of hydrogen peroxide concentration into the conical flask and start the stop clock. I must make sure I keep the syringe in the hole to block it so none of the oxygen produced will escape.
15. When the two minutes is over I will record where the finishing measurement of the water in the burette is. Then empty out the burette, clean the conical flask out. Then I am able to repeat it all over again with a different concentration.
16. I must do the experiment two times s I get two results for each concentration I have so then I am able to find the average of the two of them and get more accurate results.  

∙Diagram of Apparatus

        Please see separate sheet.

∙Precautions

        The precautions I will take to make my experiment as safe and accurate as possible are: I will make sure I thoroughly wash out the conical flask after each time I use it to prevent any contamination which will causes my results not to be as accurate. To prevent contamination as well I will use separate syringes for each substance I use. To try and get the measurement as exact as possible to 5cm3 for the yeast I shall use a pipette, which is more accurate and precise than just poring the yeast into a measuring cylinder.

        For my safety and others around me I am going to make sure everything is clean and tidy and I know were everything thing is that I will need. I will table everything thing so I know exactly what everything is to prevent any accidents. Though out the whole experiment I will make sure I keep my safety goggles on to prevent anything going into my eyes. I will also have my hair tied back to stop it getting in the way, or even knocking some the equipment over.

∙Result tables

 Table 1 – This shows the results for the first experiment I did. The ‘stating measurement’ and the ‘final measurement’ columns are the raw data, which I received straight from the experiment. While the ‘total oxygen produced’ column is processed data that I had to work out after the experiment using the raw data got.

To find the total amount of oxygen produced, I had to take the stating measurement of the level of water n the burette. Then minus the 5cm3 for the 5cm3 of hydrogen peroxide concentration that is squirted into the conical flask and. Finally minus the final measurement of the water in the burette.

Table 2 – This table shows the results for the second experiment I did. I did everything exactly the same, as well as using all the same equipment and measurements. To find out the process data I used the same formula as in table one, which is;

Starting measurement – 5cm3 – Final measurement = Total oxygen produced

Table 3 – this table shows the averages of tables 1 and 2 on the total oxygen produced for each concentration of hydrogen peroxide.

∙Graph -