Investigating a factor that affects the rate of reaction

Aim - To investigate the effect of concentration on the rate of reaction

- To investigate the reaction between hydrochloric acid and magnesium


1) -I predict that the higher the concentration of hydrochloric acid the faster the time will be for the magnesium to dissolve.

2) -I predict that the higher the molar of hydrochloric acid, the more hydrogen gas will be given off.

3) -I predict that the higher the concentration of hydrochloric acid the faster the rate of reaction. This will therefore mean that the rate of reaction will be faster.

4) - I predict that when I double the concentration, I would expect the rate of reaction to double with the concentration.


Rates of Reaction measures different reaction rates and tells us things that affect the speed of a reaction.

Seven factors that affect how fast a reaction takes place are:

- Temperature

- Catalyst

- Pressure

- PH

- Surface area

- Concentration

- Light

We can change speeds of reactions in three ways-

- Increasing the surface area

- Increasing concentration

- Raising the temperature

- Adding a catalyst

There are three ways to measure the speed of a reaction and these are precipitation, change in mass and the volume of gas given off.

The four things that are suitable for the magnesium reaction to affect how fast it takes place are -

- Temperature

- Turbulence

- Concentration

- Surface area

Concentration is the best factor to for this magnesium and hydrochloric acid reaction because it is easy to undertake.

In this experiment between hydrochloric acid and magnesium ribbon. The hydrochloric acid will dissolve the magnesium strip. This should produce hydrogen gas.

The chemical equation for this reaction is

Mg (s) + 2HCL (aq) Mg Cl (aq) + H (g)

This chemical reaction involves reactants which when mixed may cause a chemical reaction. This in turn may produce different products.

What I am expecting to see in the beaker is the magnesium and hydrochloric acid reacting together to form fizzing in the solution and I think I will also see bubbles, which I may see slowly or fast depending on the amount of concentration. Magnesium will eventually break away and eventually dissolve.

The concentration of the hydrochloric solution affects the rate of the reaction. If the concentration is too high, there will be more collisions between the enzymes, which will also increase the rate of reaction. On the other hand, if the concentration is to low then the collisions of enzymes with substrates will slow down or stop making the rate of reaction slower. This means that there will be less frequent collisions between the atoms. When there are more particles (reactants) present, the more likely a collision, and so the higher the reaction rate. Source - (GCSE Bitesize chemistry, by David Smith)

These factors will affect the rate of reaction. This is because of the collision theory. The collision theory shows us that it is necessary for the reacting particles to collide with each other particles. This is so there is enough energy to form or break bonds between the particles. If however, the particles do not have enough energy then the particles will bounce back not causing a collision. The minimum amount of energy needed for a collision to take place between the particles is called the activation energy. Source - (GCSE chemistry revision guide, by Ian Lee)

The Maxwell Boltzmann curve is a graph that predicts the probability that the different particles will collide with each other at different temperatures. On the graph shown below the dark shaded area shows the particles that have enough energy to collide with each other. The very light shaded area is the particles that do not have enough energy to collide because they do not have enough energy. The line on the graph showing the activation energy is the minimum amount of energy that is needed for the particles to collide. This Maxwell Boltzmann curve can be related to the reaction between magnesium and hydrochloric acid because the graph shows us how much energy is needed for the particles to make and break new bonds. The Maxwell Boltzmann curve is shown below -

The equation K[a] shows the number of variables that are