Rate of Reaction Investigation

Rate of Reaction Investigation

Aim:

To find out how altering the concentration of Sodium Thiosulphate

affects the rate of reaction with Hydrochloric Acid.

Background Information:

Chemical reactions rely on molecules colliding with each other. For

products to be made bonds need to be broken and then bond made. The

energy needed to cause these collisions is called the activation

energy. If the energy given to the reaction is too low, then it will

not proceed - this is the reason why heating often increases rate of

reaction (as heating increases the molecules energy).

The factors that will affect the experiment, with the reasons for

them, are below. All are based on collision theory, which says

reactions can only occur when the reactant molecules collide with each

other.

Concentration.If the concentration of one or both of the reactant

solutions is increased, the likelihood of a collision increases. The

more molecules of reactant there are in a given volume, then the

higher the probability of a collision.

Temperature. Because the molecules in the solutions will move faster

when they are hot, higher temperatures also lead to faster reaction

rates. It is the same as children in a confined playground - they take

up more space every second if they move fast, so are more likely to

collide.

Stirring.Because stirring moves the molecules around faster, they are

more likely to collide and therefore react. This reason is similar to

the last.

Beaker Type. When monitoring a reaction where you judge how far a

reaction has gone by how cloudy the mixture has become, then putting

the same volume into a beaker with a larger area base would mean that

you were looking through less depth of liquid than before. The liquid

would not appear as cloudy, and the rate of reaction would seem to be

less than if a smaller beaker had been used.

Prediction:

I predict that the rate of the reaction will increase when the

concentration of Sodium Thiosulphate is increased.