Chemistry Coursework - the Dissappearing Cross

CHEMISTRY COURSEWORK- "THE DISSAPPEARING CROSS"

PLANNING

Background Information:

During a chemical reaction the reacting particles must collide with each other, however, collision alone does not guarantee that the reaction will start. Reaction will only occur if the colliding particles have sufficient combined energy to get over the energy barrier between reactants and products. This minimum amount of energy that is required is called the activation energy.

* Changing the Temperature: As we increase the temperature in the reaction the particles will move more quickly and will collide more often with greater kinetic energy and more collisions will be successful. In general, an increase of 10 Kelvin causes the rate of reaction to double.

* Changing the Concentration: As the concentration of the particles increase they are more likely to collide giving more frequent collisions. The rate of reaction will increase.

* Changing the Surface Area: This can only take place in solids. Large particles have small surface area. Fewer particles are exposed and available for reaction. For example, powdered magnesium produces hydrogen more quickly than magnesium ribbon when reacted with hydrochloric acid.

* Catalysts: A catalyst is a substance that increases the rate of reaction by lowering the activation energy. Catalysts do not get used up during the reaction, i.e. they remain unchanged.

Aim:

My ain is to investigate how concentration affects the rate of reaction between Sodium Thiosulphate and Hydrochloric Acid.

Prediction:

I think that as I increase the concentration of Sodium Thiosulphate the rate of reaction will also increase.