Investigation to see how the Concentration of Hydrochloric Acid affects the Rate of Reaction with Marble Chips.

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Investigation to see how the Concentration of Hydrochloric Acid affects the Rate of Reaction with Marble Chips

Aim

The aim of this experiment is to see how the concentration of Hydrochloric acid will affect the rate of reaction between hydrochloric acid and marble chips.

Equation for Reaction

CaCO3 (s) + 2HCl                   CaCl2 (aq) + H2O (l) + CO2 

Variables

 The factors which will affect the rate of the reaction are:

  • The surface area of the Marble Chips
  • The temperature of the solution (HCl)
  • The concentration of the solution (HCl)

Concentration


By increasing the concentration per unit volume of the acid you are placing more acid particles into the same area. This means that you are more likely to get a successful collision.

 

Temperature


By increasing the temperature you are giving kinetic energy to the particles. The more kinetic energy the particles have, the faster they will move. This will mean more frequent collisions. Due to the increased energy, a larger proportion of them will be effective. This will mean an increase in reactions.

Surface Area

Increasing the surface area of the solid will mean that there is a bigger area for particles to collide with. An increased surface area will therefore mean more chance of reaction.


Therefore there will be an increase in the number of collisions, which also means a larger number of effective collisions.

I have decided to carry out an experiment in which the concentration of hydrochloric acid is varied.

I intend to keep the temperature constant by keeping the equipment in the same environment for the whole duration of the experiment. I will make sure that the temperature in this environment does not change significantly.

I intend to keep the surface area of the marble chips constant by using marble chips from the tub labelled small. These will not all be exactly the same, but this may be an error I can discuss later in the evaluation.

Background

 Collisions between reactant particles are required if a reaction is to occur. For a reaction to occur the activation energy is required.

The activation energy is the energy required for a reaction to be started. Marble chips rely on surface area to react. If the surface area is increased then there is a bigger area for the HCl to react with. The liquid HCl relies on concentration for its reactions to occur. A solution with a higher concentration will react more readily with a solid because there are more particles to make contact.

Prediction and Preliminary Work

I predict that as the concentration of hydrochloric acid increases so will the rates of the reaction. From my preliminary work I have found that I will have the marble chips in excess. Also I will use 100cm3 of acid and 4g of marble chips. I also predict that the graph that shows 1/time taken to produce a given mass of CO2 will be a straight line through the origin. As you increase the concentration of the acid the rate of reaction will also increase. I have come to these conclusions because of the reasons I have stated in the background and variables sections.

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I believe that the graph that shows 1/time against the concentration will be a straight line through the origin partly because I know this already, but also because after 0 minutes the reaction has not started yet so no mass of CO2 will have been produced.

In my preliminary work I used the concentrations 1.0 and 2.0mol/dm3 and I tried to see which size marble chips I would use in regards to the rate of their reaction. I put 4g of small, medium and large into different beakers with 100cm3 of the different concentrations and I saw which reaction finished ...

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