The rate of reaction changes Essay
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Fair Testing In this investigation I will keep constant the following to make a fair test: The volume of Hydrogen Peroxide in each experiment. The mass of catalyst used in the preliminary work but this will be the independent variable in the second part to the investigation. The same equipment as there may be minor changes in the size of each piece of equipment or the readings on the side of the equipment. Use the same method for each experiment so there will not be any major differences.
Only change the mass of catalyst used in the second part of experiment.
Measure temperature in the room with a thermometer. Ensure that the side-arm conical flask is washed out properly every time you finish an experiment to stop contamination. Use the substances from the same bottle because if you use a different bottle the concentration maybe slightly different which could affect your results. Obtaining Evidence Safety Whilst this experiment is relatively safe, there are still some safety considerations to be adhered to: We wore eye goggles when we used Hydrogen Peroxide in case some of it splashed up into our eyes because it is dangerous and can cause burns.
We had to be careful that if any Hydrogen Peroxide got onto our hands we had to wash it off straight away with water because it is corrosive. We had to be careful how we held the gas syringe because there was a danger that the sliding bit could slip out. We also had to make sure that it did not fall out of the end of the syringe when the experiment was going on. We also had to be careful with all equipment that was made out of glass in case it breaks. Results Time (secs) Mass MnO2 0. 05g (cm3 O2) Mass MnO2 0. 10g (cm3 O2) Mass MnO2 0. 15g (cm3 O2) Mass MnO2 0. 20g (cm3 O2) Mass MnO2 0.
Analysing Information The table above shows that the most Oxygen was produced with 0. 3 grams of Manganese Oxide. It also shows that the amount of Oxygen produced increased gradually with the mass of the Manganese Oxide. With these results we were able to work out the rate of reaction for each set of results:
Rate of Reaction = volume of gas Time Mass The rate of reaction also increased with an increase in the mass of Manganese Oxide. The rate of reaction gradually increased with each different mass of the catalyst except from 0. 15g to 0. 20g where there is a large jump in the results. Also the rate of reaction goes down from 4. 5cm3/s to 4. 0cm3/s from 0. 2g to 0. 25g. This is a mistake in the results and could have occurred in many ways.
Probably the most likely answer is that we were slow in putting the bung on the conical flask so some Oxygen might have escaped out of the top. Another possible answer could be that we made mistakes in measuring the amount of Oxygen given out at exactly every five seconds. Most of the results are as we expected from the beginning in that the rate of reaction will increase with the more mass of Manganese Oxide. This is because there is more surface area of the catalyst for the Hydrogen peroxide to react with as said in the collision theory. Evaluating Information The experimental procedure is simple, but effective.
It worked very well but we could have made a few improvements in the procedure. One improvement we could have made was that we could have some sort of electrical device which would measure the amount of Oxygen given off and display it every five seconds digitally. Another problem we were having is that it was difficult to get exactly the right mass of Manganese Oxide every time. Another thing is that sometimes it would take quite a lot of time to pour the Hydrogen Peroxide into the conical flask and then by the time we put the bung on, the reaction had started and we would loose some Oxygen through the top.
This is important because the results at the beginning are the most important to work out the rate of reaction. All together our results were very successful but we did have on anomalous result with 0. 25g of Manganese Oxide, which was slower than the 0. 20g result. The reasons for this I have already discussed above. We could have got better results by repeating the experiments maybe a few more times so we could get lots of results and then get a better average from those results. This would give us more accurate results and maybe not have the anomalous result.
We could also have extended the preliminary work by trying out more catalysts to see if we could have got a better one than Manganese Oxide.
Bibliography “Chemistry For You” by Lawrie Ryan “The Essentials of GCSE Chemistry” by Mary James 1 Show preview only The above preview is unformatted text This student written piece of work is one of many that can be found in our GCSE Patterns of Behaviour section.