Rate of Reaction

PLANNING
I am going to investigate how the concentration of an acid affects the rate of reaction. The rate or speed of a chemical reaction is a measure of how fast the reaction takes place. There are a few factors that affect the rate of reaction: concentration, surface area, temperature and using a catalyst.

Concentration – as you know, particles in a solution move about, they bump into one another, this is the collision theory. If the concentration of the acid is increased, the number of ions moving about in the solution is increased, and therefore there will be an increase in the number of collisions. However not all of these collisions will have enough energy to react because they do not have enough energy to cross the activation energy barrier. Nonetheless, the more often that particles with enough energy to collide, the more chemical reaction will take place. I think that the rate of chemical reaction will increase if the concentration of reactants increased. I f the concentration of reactants is decreased; the rate of reaction will decrease.

When pieces of magnesium are placed in a boiling tube containing hydrochloric acid, bubbles of hydrogen are seen as the magnesium dissolves and magnesium chloride is formed. If the acid is very dilute then only a few bubbles are seen. If more concentrated acid is poured onto a similar quantity of magnesium two things happen; more bubbles of hydrogen is seen and the reaction stops after a shorter period of time. From these observations, it can be said that increasing the concentration of a substance will increase the rate at which it reacts.

Surface Area – in a solid a reaction can only take place on the surface of the metal. If in this reaction we use smaller pieces the reaction will happen faster. The diagram shows a piece of magnesium, as well as the same piece cut up into smaller pieces. Eventually a powder is produced. By cutting it up the amount of surface area has been increased that is available for the... [continues]

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