Magnesium and hydrochloric acid react together readily. Plan and carry out an investigation testing a factor that you think will effect the reaction. You may only use equipment available to you in the science laboratory.

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Carla Jones 11y set 1               Chemistry Assessment    Centre no. 29200

Candidate no.8159                                                                        

Brief

Magnesium and hydrochloric acid react together readily.  Plan and carry out an investigation testing a factor that you think will effect the reaction. You may only use equipment available to you in the science laboratory.  Your plan must be approved before you start the practical work, as must the preliminary work.

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Background information.

In the reaction between hydrochloric acid and magnesium ribbon, the hydrochloric acid will react with the magnesium and produce hydrogen gas. All chemical reactions involve reactants which when mixed may cause a chemical reaction which will make products. In my experiment the reactants are hydrochloric acid and magnesium ribbon. The chemical reaction takes place when the magnesium ribbon is dropped into the hydrochloric acid. The products that are formed during this reaction are hydrogen gas and magnesium chloride. The formula equation for this experiment is:

Mg + 2HCl (r) MgCl2 + H2

Magnesium + Hydrochloric acid (r) Magnesium Chloride + Hydrogen

The rate of reaction between the product and the reactant will increase or decrease depending on certain factors. The factors that may affect the rate of reaction are: - temperature of the Hydrochloric Acid, mass of the magnesium ribbon used, concentration of the Hydrochloric acid, surface area of the magnesium ribbon used, the use of a catalyst and the temperature of the acid.
All of these factors will change the rate of reaction because of the Collision Theory. This is a theory that is used to predict the rate of a reaction. The Collision Theory is based on the idea that for a chemical reaction to take place, it is necessary for the reacting particles to collide with each other with enough energy to break or form new bonds between the other particles, which is called a successful collision. If when they collide and they do not have enough energy to break or form new bonds then they will simple bounce of each other, causing an unsuccessful collision.

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Factors which affect the rate of reaction.

The factors that I could chose to look at are:

The use of a catalyst

Temperature of the reactants

Concentration of the reactants

Surface area of solid reactants

I haven’t yet decided which of these factors I am going to chose to investigate. So I will look at each one in a little more detail.

The use of a catalyst:

A catalyst works by giving the particles which are reacting somewhere that they can collide together, they do this on a surface that is provided by the catalyst that they are able to stick to.  Catalysts are never used up during the procedure this lowers the amount of energy that is needed for successful collisions to take place.  This means that more collisions will take place making the reaction faster.

 Temperature of the reactants:

When the temperature increases, the particles gain more energy and as a result start to move more quickly.  When the particles are moving around at a quicker rate there will be a greater chance of them making collisions.  The more successful collisions that occur, the faster the rate of reaction.

          Low Temperature                                              High temperature

               

Concentration of the reactants

This factor will increase the number of collisions. An increased concentration means that an increased number of particles will be present. This in turn will mean that there will be a greater number of collisions taking place, which will effect the reaction rate – making it faster.

In a gas, increasing the pressure (concentration). Means that the molecules will be more compact so there will be more collisions as a result.

Low Concentration                                                                    High Concentration

Surface area of solid reactants

If any one of the reactants used in the investigation is a solid then breaking it up into smaller pieces will increase its surface area.

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The smaller the pieces the larger the over all surface area, this will result in an increased number of collisions, and an increased reaction time.

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After having looked at all the possible options of what I could look at, I have decided to find out how the concentration of Hydrochloric acid effects the rate of reaction.

Prediction.

I predict that the higher the concentration of the acid, the faster the rate of reaction will be. I predict this because ...

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