Investigate the rates of reaction, which affect by the change of concentration of the acid.

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HOW THE CONCERNTRATION OF THE HYDROCHLORIC ACID AFFECT THE RATE THE OF REACTION BETWEEN MAGNESIUM AND HYDROCHLORIC ACID

PLANNING:

AIM:

I am going to investigate the rates of reaction, which affect by the change of concentration of the acid.

In this experiment, I am going to look at the reaction between hydrochloric acid and magnesium. They react as the equation below:

Hydrochloric Acid +Magnesium---- Magnesium Chloride + Hydrogen

     2HCL     +    Mg--------    MgCL2       + H2

The product of the reaction in this experiment is Magnesium Chloride and hydrogen. To measure the rate of the reaction, I am going to measure the volume of the hydrogen in order to measure the rate of the reaction.

FAIR TEST:

According to the collision theory, a reaction will only occur where the particles of the reactants meets and combine. This means that the change of the rate of reaction is causes by the amount of particles to collide more often or less often. For instance, the increasing in the reaction must cause more particles to collide harder and make it happen more often.

As the result, there are many ways, which can affect the rate of reaction:

  • Concentration: increase the concentration will increase the rate of reaction. As we increase the concentration, there are more particles in a given volume of solution. Therefore there are more collisions in a given time.
  • Surface area: the surface of the magnesium will affect the rate of reaction. If we increase the surface area of the Mg, the rate of reaction will increase as well. We increase the chances of particles colliding by increasing surface area.
  • Temperature: the particles gain energy and move around more quickly. Therefore we get more collisions in a given time. The collisions are also harder (more energetic) and are more likely to result in a reaction.
  • Pressure: Increasing the pressure will result in an increase in the rate of reaction. I will not test this variable because the school doesn’t have the facility.
  • Using a catalyst: a catalyst will not be used in this reaction.
  • The mass of magnesium: the mass of the magnesium is a way of measure the quantity of Mg is used in the experiment.
  • Volume of acid: this will be amount of hydrochloric acid that be reacted in the experiment.
  • Light intensity: the light intensity has a very small affect on the experiment so I am not going to take account in my experiment.

I have chosen to investigate how concentration affects the rate of reaction, to make a fair test I will have to keep all variables the same except the concentration.

RANGE:

To decide on the values of variables, I am going to calculate approximately how much HCL and Mg is suitable in the experiment. The calculation shows below tell me how much Mg and HCL minimum I need to carry out the experiment.

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1 mode of any gas at room temperature has a volume 24000cm3

The volume of 2 test tubes is about 100cm3

If 1 mole Hydrogen is 24000cm3, then 2 test tubes (100cm3) is about

100cm3/24000 cm3=1/240 mole

From 2HCL + Mg ------ MgCL2 + H2,

1/240 mole Hydrogen =1/240 mole Mg = 2/240 mole HCL

mass Mg =1/240 *24=0.1 g

2 mol/dm2 =2 mole in 1000 cm3 

Minimum volume HCL: (2/240)/(2/1000)=4.2 cm3

As the calculation show above, in the experiment, we need the minimum volume HCL 4.2 cm3 and 0.1 g magnesium.

PRELIMINARY EXPERIMENT:

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