How am I going to measure the amount of gas given off?
To measure the rate of reaction I am going to measure the speed at which at which the gas is given off. I can do this in three ways, the first being to count how many bubbles are given off, the second is to measure the change in mass as the gas is let off, and the third is to use a gas syringe to measure the volume of gas given off in total.
I have decided to choose the gas syringe method, as it will give me more accurate results and will basically be a lot easier to do. I did not choose the counting how many bubbles were given off, as if it was a fast reaction the bubbles would be given off to more quickly and I wouldn’t be able to count them. I also did not choose the change in mass from start to finish, as I will only be able to measure a certain amount.
The Apparatus list:
The apparatus I am going to use are:
Heat proof mat
- Tripod
- Gauze
- Bunsen burner
- Conical flask
- Tile
- Clamp
- Gas syringe
- Thermometer
- Scales
- Stop clock
- Knife
- Goggles
- Potato
- Hydrogen peroxide
Here is a lay out of the apparatus I am going to use:
Method
- Collect and set up all the apparatus I will be using.
- Cut up the potato, and measure it to make sure it is 10 grams.
- Measure out the Hydrogen peroxide, and make sure it is 50cm and place in the conical flask.
- Heat the hydrogen peroxide to the temperature needed, on the Bunsen burner.
- Add the potato too the hydrogen peroxide, place the rubber bung on and start the timer.
- Stop the timer after 100cm of oxygen has been produced.
I will use five different temperatures, and I will repeat each one three times. I will do this so that I can average out my results, to make them more accurate. I will then put all my results in to a table and from that I will draw a graph.
Is it a fair test?
It is very important that I keep this experiment a fair test, otherwise my results will come out totally wrong. To make sure my experiment is a fair test, I will make sure that only the property changing is the temperature and nothing else. I will do this by making sure that at the start of every test I measure the hydrogen peroxide and potato accurately. As if one of them is not the right measurement, I may get anomaly result.
Prediction
I predict that in this experiment, as the temperature increases so will the rate of reaction. I know this because from previous knowledge, I know that as the temperature increases so will the rate of reaction to a certain temperature. So I also predict that once the temperature reaches about fifty, the reaction will dramatically slow down and even stop as the enzymes will become denatured.
Results:
Results for 5 different temperatures, using potato and hydrogen peroxide:
Analysis:
From my results you can clearly see that the rate of reaction increases as the temperature does, to a certain temperature. You can clearly see this in Graph 2.
Graph 1 tells me how long it takes for 100cm to be made for temperature from 10°c to 50°c. From graph 1, I can tell that at a lower temperature it takes longer to produce gas. But at 40°c, the most gas is produced in the shortest amount of time, which means that this is the enzymes optimum level. Also that at 50°c the amount of time it takes for gas to be produced starts to slow down, as the enzymes start to become denatured.
Graph 2 tells me how much gas is produced every second for temperatures 10°c to 50°c. From Graph 2, I can tell that at temperatures 10°c and 20°c, the gas production per second is very low which means the enzymes is not very active. I can tell this because on the graph the numbers plotted are very small. I can also tell that at the temperature 30°c, the enzymes are becoming more active. I can tell this because from temperatures 20°c to 30°c the tilt of the graph is very steep and the range between 20 and 30 is much greater than between 10 and 20. But at 40°c, the enzymes are at their optimum level (highest rate of reaction). I can tell this from the graph, because at 40°c the amount of gas produced per second is the biggest amount produced in the graph. Then at 50°c, the enzymes are becoming denatured and slowing down. I can tell this from the graph, by the fact that between 40°c to 50°c, the rate of reaction drops so dramatically.
I did not have enough time to do a test for 60°c, but from the results I have so far. I can tell that at 60°c, the enzymes would have become totally denatured. I can tell this by the way the graphs slope/line decreases very steeply after 40, so from this I would think it would continue on decreasing at a rate like this.
The prediction I made has been proved correct, from the evidence in my table and in graph 2. In my prediction I said that as the temperature increased, so would the rate of reaction, but when the temperature reached about fifty, the reaction will dramatically slow down and even stop as the enzymes will become denatured. Although I did not have time to do any experiments over 50°c, I can see from graph 2 that at 60°c the line would have dropped so much that it is very unlikely that a reaction will take place after 60°c. So all in all my prediction was right.