F336-hydrogen peroxide individual investiation

Contents

An investigation to show the effects of Manganese (IV) Oxide catalyst (MnO2) and Catalase on the decomposition of Hydrogen Peroxide (H2O2)

Planning

Using two catalysts at two different temperatures, Manganese (IV) Oxide and Catalase, I can then determine which is the most effective catalyst by examining the different activation enthalpies

Hydrogen peroxide is made by quite a few enzymes in the body. Hydrogen Peroxide is a poisonous by-product of metabolism, this can kill cells. In particular, some enzymes breaking down certain amino acids and fatty acids (D-amino acid oxidase and acyl-CoA oxidase) make significant amounts of hydrogen peroxide. Since hydrogen peroxide can be damaging to normal tissue, these enzymes are kept inside specialized organelles inside cells called peroxisomes. The peroxisomes also contain large amounts of catalase to breakdown the hydrogen peroxide before it can escape.

Catalase is also found in food such as potato and liver. Catalase breaks down the Hydrogen Peroxide molecule because the shape of the molecule matches the active site of the catalase enzyme. The equation below is the breaking down of Hydrogen Peroxide into water and Oxygen.

2H2O2 (aq) → 2H2O (l) + O2 (g)

Hydrogen Peroxide is also broken down by inorganic catalysts such as Manganese (IV) Oxide-

MnO2 (s) + 2H2O2 (aq) --> MnO2 (s) + O2 (g) + 2H2O (l)

The type of catalysts that I am going to be using in this decomposition reaction are-

Heterogeneous- is where the catalyst is in a different phase to the reactants. The Hydrogen Peroxide solution is in a aqueous state and the Manganese(IV) Oxide catalyst is in a solid state. 2

For a successful collision to occurs the particles have to collide at enough energy for the reaction to occur, only a fraction of the particles have enough energy for the reaction to occur. The particles also need to collide at a right orientation at the moment of impact to break existing bonds and form new ones. The minimal amount of energy required is called the activation energy.

The surface area also affects the rate of reaction, the larger the surface area the higher the reaction rate. More surface area means more reactions therefore speeding the reaction up. I’m going to be using Manganese(IV) Oxide which is a powder, meaning it has a larger surface area for the reactions to take place.

The image above shows how different concentrations affect the rate of reaction. On the left, there is a low concentration of reactant so there are fewer collisions as there are fewer particles which decrease the chances of successful collision meaning the reaction rate will decrease.

Whereas on the right, there is a much higher concentration of reactant particles, so there are higher chance of collision so this increases the chances of successful collision meaning the reaction rate will increase.3

The equipment I will need for this reaction is: