Science-chemistry practical-To find out how the concentrations of the reactants affect the rate of reaction

Essay by marcecko72 March 2005

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Aim:

To find out how the concentrations of the reactants affect the rate of reaction

Variables:

Possible variables that could speed up the rate of a reaction are;

Temperature

Catalyst

Surface area

Concentration

Chosen Variable= Concentration=Independent Variable

Scientific knowledge:

Reactions can go at all sorts of different rates e.g. a slow reaction would be the rusting of iron and a really fast reaction is an explosion. The speed of a reaction can be observed either by how quickly the reactants are used or how quickly the products are forming. For this experiment I will be observing how quickly the reactants are forming (how quickly the solution turns milky white), this is because this method is a lot easier to measure. This is called the precipitation method. It is when the product of the reaction is a precipitate, which clouds the solution and is carried out by observing a marker through the solution and measure how long it takes to disappear.

Other methods include finding out the change in mass by using a mass balance and working out the volume of gas given off with the use of a gas syringe.

Reaction rates are explained by the Collision Theory, which explains that the rate of reaction depends on how often and how hard the reacting particles collide with each other. The particles have to collide with each other, hard enough in order to react. Therefore more collisions increase the rate of reaction. The factors that affect rate of reaction include temperature, increasing the temperature makes the particles move quicker and collide more. At a higher temperature there will be more particles colliding with enough energy to make the reaction happen. The initial energy is known as the activation energy and it's needed to break the initial bonds. However in this...