To investigate the factors affecting the rate of reaction.

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Tom Green 11px Chemistry

Aim

To investigate the factors affecting the rate of reaction.

Prediction

There are several factors that affect the rate of reaction. Each one will affect the rate in its own way. The things that influence rate are concentration, temperature, catalysts and surface area. They will all affect the rate of reaction by speeding it up not slowing the reaction down. If you double the concentration then the rate of reaction will also double. If we increase the temperature by ten degrees then the rate of reaction will double.

I predict that if the concentration of the sodium thiosulphate increases then the rate of reaction will also increase meaning the cross under the beaker will disappear quicker. Also this will work the opposite way round if the concentration is lowered. This means that the graph drawn up in my analysis will have a positive correlation, and will probably be curved as the increase in rate of reaction will not be exactly the same as the concentration is increased.

Scientific Knowledge

The starting materials of a chemical reaction are called the reactants the finishing materials are called the products. Depending on whether the reactants change to the products quickly or slowly determines if the reaction is quick or slow. (If the reactant turns to a product slowly means it’s a slow reaction and visa versa). There are many factors that can change how fast a normal reaction between chemicals occurs. These factors can be the reactants size of particle, the concentration of reactants in solution, temperature, surface area, and pressure, presence of light and the addition of a catalyst. The factor in this experiment that I will be investigating is the concentration of the sodium thiosulphate. Concentration means how much water is combined with the substance, concentration can also be known as the molarity.

A reaction takes place when two particles from different chemicals are moving around as they have kinetic energy and then they collide. If the particles have enough energy between them there is a successful collision resulting in a reaction. If the particles do not have enough kinetic energy and therefore not enough energy they bounce apart and no reaction take place. When various reactions take place, different minimum energy levels are needed to make a successful collision resulting in a reaction.

When you increase the concentration the amount of particles will increase. This means there will be more collisions so the probability of successful reaction increases. All this means is the rate of reaction will be quicker.

In the diagram it shows the concentration being increased meaning there are more particles to create collisions. This means the rate of reaction will be doubled.

If you increase the temperature the particles gain more energy. This then means they have more kinetic energy so they move around quicker. If they move around quicker they will bounce into other particles more frequently and more particles will have the activation energy that is needed for a successful reaction. This once again speeds up the rate of reaction.

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If you add a catalyst to a reaction this will also speed up the reaction. The important factor about using a catalyst is they do not use up after being added to a reaction. Catalysts work because they lower the activation energy, which is the minimum energy to bring about a reaction. If you lower the energy level more particles will have the minimum level that is needed. This doesn’t mean there will be more collisions it just means they are more likely to be successful. Examples of using a catalyst are the ‘cracking’ of hydrocarbons using broken pottery and ...

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