Rates Investigation Report.

Apparatus:

Ice Cream Tub

Conical Flask

100ml Measuring Cylinder

Delivery Tube

Clamp Stand

Clamp

Yeast

2 Placed Scales

20ml Measuring Cylinder

Hydrogen Peroxide

Water

Stop Clock

What we measured to record our results was how long it took for 20ml3 of oxygen to be produced.

What we changed each time we carried out the method was the concentration of Hydrogen Peroxide.

We controlled the concentration of Hydrogen Peroxide, we did this by using different amounts of Hydrogen Peroxide mixed with different amounts of water e.g. to create Hydrogen Peroxide with a concentration of 10 we would use 10ml of Hydrogen Peroxide mixed with 10ml of Water. We controlled this because it was one of the factors, which affected the rate of the decomposition Of Hydrogen Peroxide.

Step by Step Method

• Collect all apparatus listed above
• Set up apparatus as shown in diagram above
• Create concentration of Hydrogen Peroxide
• Place Hydrogen Peroxide into conical flask
• Add 0.5g of yeast to Hydrogen Peroxide
• Time how long it takes for 20ml3 to be collected in measuring cylinder

Preliminary Work

We started our preliminary work by collecting results for our highest concentration of Hydrogen Peroxide, which was 10vol H2O2 and our lowest concentration of Hydrogen Peroxide, which was 2vol H2O2. Here are our results:

Once we had checked that our highest and lowest concentrations were okay to use we were able to begin our full Preliminary Experiment here are our results:

After recording our preliminary results we found a problem with our method. The problem was that as the yeast has shell around it we were only getting half of the catalyst really. To solve this problem we decided to add 5ml of water to the yeast this would liquidize the yeast and therefore releasing the full power of the catalyst.

Results

These were our results using liquidized yeast as the catalyst:

 Graphs

My graphs are on the next page.

Conclusion

My results and graphs tell me that as I increase the concentration of Hydrogen Peroxide the quicker the reaction rate becomes. My graphs help show these results. My first graph time Vs concentration helps show that as you increase the concentration of Hydrogen Peroxide the quicker the reaction rate becomes, it helps show this because it curves downwards showing that the higher the concentration the quicker the reaction. My second graph which is rate Vs concentration also shows that the higher the concentration of Hydrogen Peroxide the quicker the reaction rate, the graph helps show this because it sort of curves upwards showing that the higher the concentration the quicker the reaction rate. My prediction was very accurate because I predicted that the higher the concentration of Hydrogen Peroxide the quicker the reaction rate would be. My results and graphs have proved my prediction to be correct. Scientific reasons for why this happens are that as you increase the concentration of Hydrogen Peroxide the amount of Hydrogen Peroxide particles increase and therefore they move around more often during a certain time and collide more often with each other. At first I thought we may have had an anomalous result when the 2vol concentration of Hydrogen Peroxide took so long to produce 20ml3 of oxygen but as this result repeated itself through our experiments I think that it must be correct.

Evaluation

I am glad that we did our preliminary work otherwise we would not have been able pick up on an error in our method that error was that we had not liquidized the yeast to use its full affect as the catalyst. Further ways to back up our results would be to check our results with another groups just to clarify that our results are along the right lines, although I believe that our evidence is of a high quality anyway.