Investigating the effect of a concentration on the rate of reaction.

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Investigating the effect of a concentration on the rate of reaction

The rate of reaction tells us how quickly a chemical reaction happens. The rate is measured in time and can be useful to find out how much of the product is created in a certain amount of time, which can be useful in industry. The rate is measured from when the reactants are placed together, until they have finished reacting and created a product.

Collision theory: chemical reactions only occur when reacting particles collide with each other with sufficient energy to react.

(The essentials of AQA chemistry, Mary James)

Activation energy: the energy needed to start a reaction

Catalyst: a substance which speeds up a chemical reaction. At the end of the reaction, the catalyst is chemically unchanged. It lowers the activation energy.

(Chemistry for You, Lawrie Ryan)

Planning

I have chosen to pursue and experiment to investigate the rates of reaction between Calcium Carbonate and Hydrochloric Acid.

2HCl + CaCO3 → Ca(Cl2)+ H2O + CO2

Hydrochloric acid + calcium carbonate → calcium chloride + water + carbon dioxide

There are four factors which I considered; each of them will affect the rate of reaction:

  1. Temperature

I think that the temperature of a solution will affect the rate of reaction. If it is at a higher temperature, then the particles in the solution are applied with more energy from the heat and move around more quickly and cause more collisions. These collisions are the cause of reaction. The higher the temperature gets, there more collisions, so the quicker the experiment will react. A higher temperature increases the rate of reaction.

  1. Concentration (Pressure for gases)

I think that the concentration of the solution will affect the rate of reaction because if there is a higher concentration, the more particles it contains, meaning more collisions will occur, causing the experiment to react more quickly. A greater concentration increases the rate of reaction.

  1. Catalyst

I think that adding a catalyst will affect the rate of reaction, as the catalyst provides the activation energy for the experiment to start reacting, the more efficient the catalyst, and the more of it added, the quicker the reaction can start, so the rate of reaction is faster than without adding a catalyst. A catalyst increases the rate of reaction.

  1. Surface area

I think that the surface area will affect the rate of reaction as if there is a greater amount of surface area on the reactant, there is more of it exposed so the particles of the other reactant can collide with it and case reactions to take place. The rate of reaction increases when there is a larger surface area.

Same amount of marble chips- different surface areas

The thick line shows where the acid can react with the marble chip, the diagram on the right shows that the increase in surface area means there is more surface for the acid to react with., so the reaction can take place more quickly.

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Prediction

I evaluated each of the factors and I have chosen to pursue the experiment by investigating the effect of a concentration on the rate of reaction. I chose to investigate the concentration because this experiment is easier to pursue than the others because it takes less time, resources and is easier to keep the variables controlled than in experiments investigating the other factors, which will hopefully give more accurate results.

I think that as the concentration increases the rate of reaction will also increase. I think this because as the concentration increases, it means there are more particles ...

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