Prediction:
I predict that an increase in the surface area and number of cubes will cause the rate of reaction to go faster and an increase in the amount of oxygen evolving because like I said before an increase in surface area will cause more smaller particles to collide with each other causing a increase in the number of collision which will make the rate of reaction more faster and more oxygen to evolve. Also I predict if the concentration is increased that will cause the rate of reaction to go faster the reason for this is because like I said before there will be more number of collision taking place which will cause an increase in the rate of reaction.
Method:
First I will begin by filling up the large beaker with water, then I will put the potato on the tile then I will start cutting the potato with the knife. I will cut each potato into cm cubes with a total area of 6cm squared. For me to cut the potatoes accurately I will be using the ruler. Then I will put on my goggles for safety reasons because next I will be filling the measuring cylinder with up to 30ml of hydrogen peroxide that is dangerous which can cause skin burns and irritates in the eyes. After that is done I will put the hydrogen peroxide solution in the conical flask and I will wash the measuring cylinder to make the test fair because I will be filling that measuring cylinder with water. Then I will put a certain amount of potato cubes in the conical flask. Then I will put the cork with a plastic pipe on the conical flask to cover it. As soon as I do that I will place the measuring cylinder with water up side down inside the large beaker that is also filled with water. Then I will place the plastic pipe in the measuring cylinder which is upside down inside the large beaker that is filled with water. As soon as that is done I will start the time on the stopwatch and I will start of by taking the measurement from 0 min. I will take the reading every four minutes.
List of apparatus:
- Safety goggles
- Potato
- Test tube
- Delivery tube
- Measuring cylinder (large and small)
- Flask
- Hydrogen peroxide
- Tile for cutting potato
- Thermometer
- Knife
- Ruler
- Stop watch
- Pen/pencil.
Safety:
I need to wear safety goggles but before starting. I also did some research on the chemical hydrogen peroxide to see what I’m dealing with. The chemical is corrosive and irritant meaning it can cause skin burns and irritate yours eyes. If the following types of problem occurs than they have to take the following emergency actions:
In Eye:
Gently put water in to your eye and then go hospital immediately.
Swallowed:
Wash out your mouth, drink a glass of water and do not try to vomit and then go hospital immediately.
Spilt on skin:
Wash that area with water and if you still have burns, blisters or rash than go hospital immediately.
Fair testing:
Before starting the experiments I will clean all the apparatus after each experiment, measure the oxygen from the meniscus point, I will cut each potato into exactly 1cm , for each experiment I will add 30ml of hydrogen peroxide solution and all the experiments will last 24 minutes so that I have done fair tests. Also I will be repeating the test 2/3 times to see if my results are correct.
I will also keep the time and temperature same. I will also have to keep the volume of hydrogen peroxide same.
Diagram:
Key factors
The key factors that I will be varying are the surface area which will change the amount of oxygen produced as a result. The key factors that I will keep control of are the volume of the hydrogen peroxide solution, time and temperature. I will take about 5 or 6 readings/observations and repeat the experiment twice to get more reliable results. I have decided to draw graphs to observe a pattern/trend in my results.
Results tables
First set of results:
Second set of results:
Average results:
Conclusion:
I have produced a graph to show the average results including a line of best fit. I found out that as the surface area of the cubes increases the amount of oxygen produced also increases. This conclusion matches up with my prediction. Although the amount of oxygen produced decreased at 36 cm squared of surface area – I have explained why this occurrence has happened on my graph of averages.
There has been some odd results on my first set of experiments where the amount of oxygen produced has decreased because I had to change the hydrogen peroxide and the next bottle I got was colder than the first one, so as I explained in the introduction that the temperature makes a difference to the amount of oxygen produce-‘In order for more collisions to take place the temperature must be increased meaning more heat energy needs to be given off. Like I explained before more collisions will cause the rate of reaction to go faster. Again the more increase there is in collisions and the more temperature there is that will mean the volume of oxygen evolving will evolve faster but there will be no increase in the amount of oxygen evolving.’
On the second set of results it proves my prediction right because as the surface area increases the amount of oxygen produced also increases, and there have not been any odd results on the second set of results because I managed to use only one bottle of hydrogen peroxide through out the second experiment. I had to warm up the bottle of hydrogen peroxide with my hands because to keep the temperature same which I have explained above and also to keep it a fair test.
Evaluation:
I am generally satisfied with my results as they prove right my prediction. The points on my graph are close to the line of best fit which shows that the results are reliable.
The procedure that I carried out was suitable for the experiment and it also shows by looking at my results that it was suitable. I must admit that my results are not 100 percent accurate because I did find it hard to cut the potatoes into exactly 1 cm cubed and also another thing is I found reading the amount of oxygen produced from the measuring cylinder from eye level quite difficult but I did get used to reading it as I did a lot of eye level reading.
To make the results more accurate and reliable could have been achieved by making a machine cut the potatoes exactly into 1cm cubes which can not be achieved by first time human cutters. Also the temperature was not kept constant because I was working with 30 or more students in the same room by which they all emit a little heat from their bodies which add together to give lots of heat in to the potatoes. So it would help if we worked in separate rooms to keep temperature constant.
