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# how change in concentration affects decomposition of hydrogen peroxide

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Introduction

Method At the start of the investigation I regulate the temperature of the water bath; the water bath would be set at 30�C throughout the investigation. After the water bath was regulated I began to fill the burette with water which must be carefully released to insure less chance of spills, which would pose a safety hazard. The burette will then be inverted to allow oxygen to displace the water, in order to stop the water from leaking during inversion, I will place my thumb on the top of the burette to form a watertight seal the burette will then be inverted, this method will stop any loss of water when added into the water bath, The water level in the burette will be sustained when it is added into the water. The burette will then be held in a vertical position to allow the oxygen bubbles to rise, the water level will be measured to the 50 cm3 line for every experiment a retort stand and the meniscus point measured in the burette to 50cm3. In order to prepare the concentrations needed for the experiments a few precautions were taken account to prepare them, so my chances of error were reduced. ...read more.

Middle

By changing the percentage concentration of the hydrogen peroxide I am changing the number of substrates present in the reaction. The volume of oxygen produced indicates the rate of reaction in that the faster the oxygen is produced the faster the rate of reaction, the concentration had a significant effect on the rate of reaction, From my background knowledge I already know that when an enzyme is present in a reaction the rate of reaction increases anyway. for example the average volume of oxygen at 6% concentration the highest concentration is 0.52 (cm3/sec), however at 3% concentration the average is 0.4 (cm3/sec).this proves that the number of substrates present affect the amount of oxygen released, I can tell this because the volume of oxygen released increases due to the increased probability of successful collisions with a hydrogen peroxide molecule increases producing more water and oxygen molecules. my results not only show the trends between the concentration and the rate of reaction, they also show the volume of oxygen collected is not directly proportional to the concentration of hydrogen peroxide as the difference between each concentration when the percentage concentration is increased is not constant, for example, the difference in the volume of oxygen collected between 2% and 3% is 1.2cm3 of oxygen, whereas between 4% and 5% concentration the difference in the volume of oxygen collected is 0.6cm3. ...read more.

Conclusion

I could not start the timer and squirt the hydrogen peroxide at the same time so I worked with a partner, the problem with this squirting the hydrogen peroxide, it takes time to press all the hydrogen peroxide into the flask therefore the timing was a bit inaccurate. That limitation may have meant that the rate of reaction was not recorded at precisely the time that the reaction occurred, Because of this limitation my data may fail to show the correct rate of reaction because the reactions are happening late, the effect this limitation has on my data is my rate of reaction are lower then they should be, because some of the reaction is continuing after the 30 seconds, this would cause my graphs not to reflect the true rate of reaction. It would have been better if I had a syringe that could press all the hydrogen peroxide with less force so the timing with the stop clock would be more accurate this may have improved my results slightly. Seeing as rates of reaction are so sensitive to temperature during the experiment I found that water bath used to keep the temperature equal began to fluctuate as the experiment progressed causing changes in temperature of reactants to decrease, this would have lowered the rate of reaction as the particles would have less kinetic energy. ...read more.

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