Reaction between Magnesium and hydrochloric Acid

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benito segarajasinghe

Reaction between Magnesium and hydrochloric Acid

                           2HCl(aq)+ Mg(s)

           Hydrochloric acid    + Magnesium ribbon

Aim

My experiment will investigate the reaction between hydrochloric acid and magnesium. The aim is to establish the relationship between the concentration of the hydrochloric acid and the rate of reaction.

Since the rate of reaction may also be affected by temperature and volume, to ensure a fair test, these will be kept constant, and only the concentration of hydrochloric acid will be varied.

Prediction

My prediction is that whilst keeping all other variables being constant, the rate of reaction will be proportional to the concentration of hydrochloric acid. The higher the concentration the higher the rate of reaction. This could be due to the number of molecules of hydrochloric acid being proportional to the concentration. The rate of reaction will be proportional to the number of acid molecules that are available to collide and react with the magnesium.

The Collision Theory states that a reaction occurs between chemical reactants when they collide with enough activation energy to break any existing bonds and reform the bonds of the resulting compound. Activation energy is the minimum amount of energy that particles require for a successful collision resulting in a reaction. The conditions affecting rate of reaction are:

  1. Concentration-This determines the relative number of particles available to collide. The higher the concentration the more particles are available, hence the probability of collisions with sufficient activation energy will be increased in proportion to the concentration.
  2. Temperature – According to the Kinetic Theory the temperature of reactant will determine the kinetic energy of the particles. The higher the temperature, the greater the kinetic energy and the greater the vibrations of the molecules, the higher the probability of a collision
  3. Surface area of a solid reactant- for a solid reactant, the greater the exposed surface area, the higher the number of collisions, and the higher the resulting reaction rate. A mass of small particles finely chopped will react more rapidly than the same mass of a solid block.
  4. Mass/Volume- Since the number of active particles is proportional to the mass of the reactants, or volume for a given concentration of reactants, these parameters will also affect the reaction rate.
  5. Catalysts- a catalyst reduces the activation energy needed for a reaction to take place. This means that less energy is needed for the reaction. This catalyst action is shown in the graph below:
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lower concentration                                  small surface area

Higher Concentration

low temperature

Higher

surface area

      higher surface area

Higher temperature

 

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