Investigating the Effect of Concentration on Rate of Reaction

Investigating the Effect of Concentration on Rate of Reaction

Aim

The investigation is about the effect of concentration on the rate of

chemical reaction. In this experiment I am going to investigate the

rate of reaction of sodium litho sulphate with hydrochloric acid. The

reaction that I will use is:

Sodium litho sulphate + Hydrochloric Acid

Na2S2O3 + 2HCl

Variables

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I will change the concentration of hydrochloric acid each time. I will

use hydrochloric acid 0.1M, 0.25M, 0.50M, 0.75M and 1M.

I will keep the same the amount of hydrochloric acid and sodium litho

sulphate concentrations used.

I will be measuring the time it takes the sodium litho sulphate to

react with hydrochloric acid to form sulphur (a cloudy white colour).

Prediction

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What I think might happen is that the concentrations will mix together

and then the concentration will turn to a cloudy colour after it has

been mixed. So the smaller the concentration is, the slower the

reaction will happen.

My reasons for thinking this are that chemical reactions only occur

when reacting particles collide with each other. For a reaction to

occur particles have to collide with each other. Only a small percent

result in a reaction. This is due to the energy barrier to overcome.

Only particles with enough energy to overcome the barrier will react

after colliding. The minimum energy that a particle must have to

overcome the barrier is called the activation energy, or Ea. The size

of this activation energy is different for different reactions. If the

frequency of collisions is increased the rate of reaction will

increase. However the percent of successful collisions remains the

same. An increase in the frequency of collisions can be achieved by

increasing the concentration, pressure, or surface area.

Concentration - If the concentration of a solution is increased there

are more reactant particles per unit volume. This increases the

probability of reactant particles colliding with each other.

Pressure - If the pressure is increased the particles in the gas are