AIM: I aim to find the rate of reaction between catalase and hydrogen peroxide.
Enzymes such as Catalase are protein molecules that are found in living cells. They are used to speed up specific reactions in the cells. Each enzyme just performs one particular reaction so they are all very specific. Catalase enzymes found in living cells e.g. in yeast, potato or liver, speed up (in our case) the breaking down of hydrogen peroxide.
The lock and key analogy…
The lock is the enzyme and its active sight is where you put the key in. The key is like the substrate that comes and bonds to the active site or the key that fits into the lock.
The collision theory
The collision theory explains rates of reaction in terms of the motion of particles in the reactants. For a reaction to happen the reactant particles must collide. Only a certain amount of the total collisions cause chemical change; these are called successful collisions. The successful collisions have enough energy at the moment of impact to break the existing bonds and form new bonds, therefore leading to the products of the reaction
-Temperature. At a higher temperature, reactant particles are moving faster with greater average kinetic energy. Therefore more of them collide with enough energy to cause a successful reaction. -Concentration. At a higher concentration, there is a greater chance of reactant particles colliding with each other with enough energy to cause a successful reaction. Rate of reaction is directly proportional which means if you double the concentration it will double the rate of reaction. -Surface area. Smaller particles, e.g. in powders have a much greater surface area than lumps or crystals. With a greater surface area, more collisions can take place. Rate of reaction therefore doubles if the surface area of the reactant particles double.
I predict that as the substrate concentration of hydrogen peroxide increases the rate of reaction will also increase. I also predict that as the substrate concentration decreases, it will take more time for the oxygen to be produced. However when the enzyme molecules go beyond the number of substrates available in hydrogen peroxide the reaction will no longer increase. This is due to there being more substrate molecules to react with the active site, resulting in more frequent successful collisions. Consequently, when the hydrogen peroxide particles break down faster more oxygen and water can be released meaning a faster reaction can take place
Wear eye protection (goggles) and cover clothing when using hydrogen peroxide (apron). Wash splashes of catalase or hydrogen peroxide off of the skin immediately. Take care inserting the bung in the conical flask- it needs to be a tight fit, so push and twist the bung in with care.
When beginning my experiment I carried out a preliminary test to see what worked best, and gave the most accurate and reliable results. After my preliminary work I decided that I would use the concentrations 1cm³, 2cm³, 3cm³, 4cm³ and 5cm³ as they gave the most accurate reliable results.
- 1 x 250ml conical flask- to hold the solution
- 1 x bung with delivery tube- bung to make sure no oxygen can escape and delivery tube for the oxygen to travel through. - 1 x 100ml measuring cylinder- to contain and measure accurately the distilled water. - 1 x 25ml measuring cylinder- to measure accurately the catalase solution - 1 x 10ml measuring cylinder- to measure accurately the hydrogen peroxide - 1 x plastic tub – to contain the distilled water
- 1 x goggles- for safety purposes.
- 1 x 10ml syringe- to insert the hydrogen peroxide into the conical flask. - 1 x stop watch- to measure accurately the time it takes for the reaction to take place. - Catalase liver solution- the solution we will be investigating - 20 volume of...