Hydrogen Peroxide,
Chemical compound of hydrogen and oxygen with the formula H2O2. Pure, anhydrous hydrogen peroxide is a colourless, syrupy liquid with a relative density of 1.44. It blisters the skin and has a metallic taste. The liquid solidifies at -0.41° C (31.4° F). Concentrated solutions are unstable, and the pure liquid may explode violently if heated to a temperature above 100° C (302.4° F). It is soluble in water in all proportions, and the usual commercial forms are a 3 per cent and a 30 per cent aqueous solution. To slow the decomposition of the peroxide into water and oxygen, organic substances, such as acetanilide, are added to the solutions, and they are kept in dark bottles at a low temperature.
Diagram
Prediction
I predict that the greater the surface area of the potato, the faster a set amount of gas will accumulate in the burette. I think this will happen because more particles in the hydrogen peroxide will successfully collide with the enzyme, catalyse particles in the potato to create a reaction.
Preliminary Investigation
Method
- Set up the apparatus as shown above
- Cut the potato into cuboids with a combined surface area of the required surface area
- Put the potato pieces into the conical flasks
- Insert the bung into the conical flask and start the stopwatch
-
Stop the stopwatch when 4.5 cm3 has been displaced from the burette
- Record the time on the stopwatch
Variables
Surface area of potato
Temperature of solution
Concentration of solution
Volume of gas produced
Fair Test
To make this investigation a fair test I kept all the variables the same apart from the one we were examining, surface area. The other variables that would effect the reaction are the concentration of hydrogen peroxide, temperature of the hydrogen peroxide and the volume of potato.
Safety Precautions
To make this investigation as safe as possible we wore goggles at all times and cut the potato on a cutting tile.
Results
Graph
Anomalous Results:
Analysis
I can see from my graph that there is a direct correlation between surface area and time taken for 4.5 cm3 of hydrogen to be produced. This means my prediction was correct. There were some anomalous results but temperate fluctuations or human error probably caused these. If the temperature flux was positive then it would take less time.
Evaluation
Allow my results were fairly accurate I could improve my results by using a water bath to keep a constant temperature and using a computer to collect the gas. To then extend my work I would then investigate other factors like temperate and concentration.
