The substances that I am going to use in this investigation are Manganese Dioxide and Hydrogen Peroxide. The Manganese Dioxide is a chemical catalyst and will be used to speed up the breaking down of Hydrogen Peroxide. I am using a chemical catalyst because it would give a more accurate result compared to organic or biological catalysts. This because organic and biological catalysts are enzymes, which require a certain temperature and will need to be kept constant as they work best between that temperatures.

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For example, 37 degrees centigrade to 40 degrees centigrade are temperatures when enzymes work best. This is because enzymes are found in the human body and are used for digestion. Also the human body has a body temperature of 37 degrees centigrade, which is why the enzymes work best at that temperature. Enzymes such amylase is found in the mouth breaks down starch in to maltose. In the stomach pepsin is used to break down protein in to polypeptides. In the small intestines using the enzyme peptidase produces amino acids when polypeptides are broken down.

Also this is where the maltose is broken down into glucose using the enzyme called maltase. Hydrogen Peroxide with a chemical equation of H2O2 looks very similar to the equation for water H2O however having an extra Oxygen atom compared to water but this changes the properties of Hydrogen Peroxide. Hydrogen peroxide is a very reactive compound that can be used for a variety of reactions including bleaching and disinfecting minor wounds. Hydrogen peroxide H2O2 is made up of two hydrogen atoms and two oxygen atoms.

Hydrogen Peroxide H2O2 looks like water H2O, but that extra oxygen molecule makes this natural water additive one of the most powerful oxidizers. Hydrogen Peroxide H2O2 has many uses and is used to bleach textiles and paper products. Other industrial uses consist of Oil refining, Food processing, Landfills, etc. The Hydrogen Peroxide is constantly being broken down but at a slow rate. With the help of the catalyst, Manganese Dioxide this will speed up the decomposition of the Hydrogen Peroxide. Hydrogen peroxide typically decomposes to form water and oxygen at the rate of 10% per year.

Here is the word equation for the reaction that I have just described: HYDROGEN PEROXIDE WATER + OXYGEN MANGANESE DIOXIDE Another way of describing this equation is in a balanced chemical equation: 2H2O 2H2O + O2 MnO2 Variables There are many things involved in this investigation, which could affect the speed the speed of this investigation. These called the variables. These variables consist of the surface area, the concentration, and the use of a catalyst, the amount of the catalyst and also the temperature. Heat, light, or a catalyst can accelerate the reaction.

Surface area – If the Manganese Dioxide has a large surface area increases the speed of the reaction because there will be more space covered by the Manganese Dioxide resulting in more of the Manganese Dioxide reacting with the Hydrogen peroxide hence increasing the speed of the reaction. And a smaller surface area will have a slower reaction rate compared to a larger surface area. Concentration of the Hydrogen Peroxide – A high concentration of Hydrogen Peroxide would speed up the rate of decomposition. This because the concentration has an affect on how strong the Hydrogen Peroxide is.

The higher the concentration the stronger the Hydrogen Peroxide is likely to be. So if the Hydrogen Peroxide has a stronger concentration that will mean that it is very reactive. Therefore being reactive means it will react faster and speed up the reaction.  The use of a catalyst – There are two types of catalysts. They are biological catalysts and chemical catalysts. An example of a chemical catalyst is manganese Dioxide. A few examples of biological catalysts are carrots, potatoes and Liver. Catalysts are used to speed up reactions.

Biological catalysts contain enzymes that break down certain substances in to other, easier to break down substances. The enzyme amylase, found in the saliva, breaks down starch into maltose. A disadvantage of using biological catalysts is that they rely on certain temperatures to ensure that they work best. Enzymes in your body work best at 37 degrees centigrade, which is your actual body temperature. When Manganese Dioxide is added to Hydrogen Peroxide, the Hydrogen Peroxide is begins to break down in to two substances. Hydrogen Peroxide breaks down in to Oxygen and water.

To collect data I cannot measure the amount of water produced. This is because it will be very difficult to separate the water produced as it has been dissolved with the hydrogen peroxide. Instead I am going to measure the volume of Oxygen in centimetres cube, as the Oxygen bubbles will not easily dissolve in water. I am going to measure the oxygen by collecting the gas in a measuring cylinder, which is full of water. The theory is that when the gas goes in to the cylinder by a delivery tube, the oxygen gas pushes out the water. This process is called the downward displacement of water.

I have chosen to investigate how the concentration of Hydrogen Peroxide affects its decomposition. Prediction I think that if I increased the concentration of the Hydrogen Peroxide the speed of the reaction will increase. I also think that as I increase the concentration of the Hydrogen Peroxide, more Oxygen will be produced. This will happen because the higher the concentration the more easy it is for the Manganese Dioxide to react with the Hydrogen Peroxide. This because the concentration has an affect on how strong the Hydrogen Peroxide is.