In this investigation I will be trying to find out if the rate of a reaction changes if the concentration of the substance is altered. This will happen if the Hydrogen peroxide is decompostured.

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Rates of Reaction Coursework – Hydrogen Peroxide and Catalase

My Investigation

                    In this investigation I will be trying to find out if the rate of a reaction changes if the concentration of the substance is altered. This will happen if the Hydrogen peroxide is decompostured.

                    Hydrogen peroxide (H202) is a clear poisonous liquid, which is produced during respiration. If this builds up inside the body it can kill, so an enzyme called CATALASE stops this from happening by breaking down the build up. More about Hydrogen Peroxide will be explained in my knowledge. The decomposition of Hydrogen peroxide looks like this:

                

2H2 O2         Catalase         2H2O+02

                   

Prediction

                     I think that the higher the concentration of Hydrogen Peroxide, the more bubbles will come out. The purer the Hydrogen Peroxide, the quicker the reaction rate. Because I am going to change the concentration of Hydrogen Peroxide after each experiment, I think that fewer bubbles will come out. This is because there will be less Hydrogen Peroxide in the beaker so there will be less to decompose.

                     I also think that if I double the Concentration, I will see twice the number of bubbles, and if I divide the Concentration by 2, I expect to see half the number of bubbles (e.g.-Concentration 2 molar, 36 bubbles, Concentration 1 molar, 18 bubbles). This can be seen in the graph below.

                     

My Knowledge

Reactions happen all the time all around us e.g. a balloon bursting, a cake baking, an apple ripening and lighting a fire. Some of them are very slow, while some are very fast. Different reactions have different rates. The rate of a chemical reaction is the speed or time taken for it to happen.

The majority of chemical reactions are faster when the concentration is

higher. This is because at a higher concentration, the molecules in a substance have more kinetic energy, which means they will move around quicker. This makes it easier for them to react together.  When more water is added, the liquid will become dilute. In this case, it also means that if the concentration is higher, there will be less water particles to block the hydrogen peroxide particles to meet up with the potatoes surface. Usually, if you double the concentration, you will half the reaction rate.

Hydrogen Peroxide

                Hydrogen Peroxide is a chemical compound of hydrogen and oxygen. As explained in ‘My Investigation’, its scientific formula is H2O2. If this solution has not been altered and is pure and anhydrous, it is colourless, slightly thick and has a gravity of 1.44. Although I do not think anyone would taste it, hydrogen peroxide has a metallic taste and will blister the skin. Concentrated solutions are unstable, and, if the liquid is still pure, it can explode when heated above a temperature over 100°C. Concentrations of hydrogen peroxide higher than 50 per cent can cause serious burns. Such factors as light, heat, chemical catalysts, dirt, and rust may cause hydrogen peroxide to decompose into water, oxygen, and heat. It is soluble in water. To keep hydrogen peroxide from decomposing, it is kept in dark bottles and at low temperatures.

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Hydrogen peroxide is widely used in industry.  It is manufactured in huge quantities by the electrolysis of aqueous solutions of sulfuric acid or of potassium bisulfate or ammonium bisulphate. Solutions containing 3 to 6 per cent hydrogen peroxide are used as antiseptics and germicides and as a skin cleanser.  Higher concentrations are used in the manufacture of many chemical compounds.  They also serve as bleaching agents for textiles and paper pulp, and as rocket propellants.

Hydrogen peroxide acts as both an oxidizing and reducing agent, because the oxygen freed in decomposition readily combines with other substances. Its oxidizing ...

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