Measuring the Rate of Reaction between Hydrochloric Acid and Calcium Carbonate

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Chemistry Coursework – Rates of Reaction

CHEMISTRY COURSEWORK - Measuring the Rate of Reaction between Hydrochloric Acid and Calcium Carbonate

WORD EQUATION

Calcium carbonate + hydrochloric acid          calcium chloride + water + carbon dioxide

BALANCED EQUATION

CaCO3 + 2HCl                  CaCl2  + H2O + CO2 

STATE EQUATION

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

PART A: PREPARING

INTRODUCTION - To investigate how concentration affects the rate of reaction we will be reacting calcium carbonate and hydrochloric acid. To make this a fair test we will have to keep all variables the same except the area we are investigating. The products of the reaction between calcium carbonate and hydrochloric acid are calcium chloride and carbon dioxide. To measure the rate of reaction we will be measuring the volume of carbon dioxide produced. The size of the marble chips available will be small, large and powdered calcium carbonate. The highest available concentration of hydrochloric acid in the experiment is 2 molar

  1. The variables that I think will affect the rate of reaction are:
  • Mass – when the mass is increased the rate of reaction increases.  Then the number of collisions per second between the solid reactants and the gaseous liquid will increase.  Therefore, there will be more successful collisions every second and the rate of reaction will increase.  
  • Temperature – this is when the molecules, atoms or ions gain kinetic energy and move faster, therefore these particles will collide more frequently.  The greater proportion of the collisions have the activation energy.  There will be more successful collisions every second and the rate of reaction will increase.  
  • Surface area – when the surface area is increased the rate of reaction increases.  Then the number of collisions per second between the solid reactants and the gaseous liquid reactants increases.  Therefore there will be more successful collisions every second and the rate will increase
  • Concentration – This is the proportion of hydrochloric acid in the solution.  This will be the amount of hydrochloric acid that will be reacted with the calcium carbonate.  when the concentration increases the number of particles in a particular volume increases.  Therefore, the collision rate increase.  Therefore, there will be more successful collisions every second and the rate of reaction will increase.
  • Catalysts- the catalyst lowers the activation energy for the reaction.  Therefore a higher proportion of the collisions will have the activation energy.  Therefore a higher proportion of the collisions will have the activation energy.  Therefore there will be more successful collisions every second and the rate will increase. Catalysts increase the rate of reaction by lowering the activation energy.  
  • NB. - Size of marble chip- the size of the marble chip will affect our experiment because this dictates the surface area. The larger the surface area the more acid that will be in contact with the hydrochloric acid and able to react.

  1. I am going to study the effect of concentration on the rate of reaction.  I am going to study the effect of concentration on the rate of reaction mainly because I understood this variable more fully than the other variables.  In addition, in class we had covered a similar experiment, so I had a greater understanding of what I had to do.  

MY PLAN FOR THE PRELIMINARY EXPERIMENT

SAFETY – This is very important as acid can be very harmful to your eyes.  Therefore, you must always wear safety glasses, and we should be very careful not to drop any acid on the work surfaces.  More importantly, we should wear overalls so no acid is exposed to our clothing.  Tuck in our stools to make sure that no one falls in the laboratory, put our belongings under the table so no one can fall, we should not run with substances in our hands, and lastly, we should always stand up when conducting experiments, so if we are in danger we are able to move.  

APPARATUS– gas syringe, pipette (2), conical flask (250cm³ x2), distilled water (40cm³) 2m/dm³ of hydrochloric acid (40cm³), retort stand, 25cm³ measuring cylinder (4), calcium carbonate (1g of small chips), glass vile (2), stop clock, small calcium carbonate chips (1.55g) and a balance.

  • I will wear my safety equipment – goggles and overalls.  This is to prevent damage to myself.  
  • I will measure 1.00g of calcium carbonate small chips in a glass phile.
  • I will measure it on a balance, but I first have to measure the phile on its own, and set the balance to zero.
  • This is so that it only measures what is within the phile.
  • I will then get four 25cm³ measuring cylinders.  
  • In this, I will pour 20cm³ of distilled water in two of the cylinders and in the other two, I will pour 20cm³ of 2m hydrochloric acid.  Again in two of the cylinders.
  • If I go over, I will use a pipette to make it an exact amount.  
  • I will then get two large conical flasks 250cm³.  
  • In one of the flasks, I will then pour one of the measuring cylinders containing distilled water and one of the measuring cylinders containing hydrochloric acid into the conical flask.  
  • I will then set up the gas syringe and make sure that it is pushed in fully.  Adjust the height of the syringe making sure that it is able to reach the conical flask.    
  • I will collect a stopwatch and make sure that it is set at zero.  
  • I will have the conical flask on the retard clamp so that as soon as I pour in the small chips of calcium carbonate I can push the rubber bung in.  
  • I will put the small chips in the concial flask, and I will begin to swirl the flask.
  • At the same time, I will start the stop clock, as soon as I have put the small chips inside.  
  • From then on, every 10 seconds I will note down how much carbon dioxide has been given off.  
  • This will be done until a) all the small chips have been dissolved or b) the gas syringe reaches 100cm³ of carbon dioxide before it has all dissolved.  
  • I will repeat the experiment once more, however this time; I will be measuring out only 0.55g of small calcium carbonate chips.
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Prediction

In order for a reaction to occur, the reacting particles must collide.  The colliding particles must collide with sufficient energy for a reaction to occur.  The minimum amount of energy which they needed to have when they collide is known as the ACTIVATION ENERGY.  If they have less than the activation energy, no reaction will occur when the particles collide.  When the reacting particles collide with the activation energy, the collision is successful and a reaction occurs.  The rate of reaction is higher when there are more successful collisions i.e. when more collide per second.  

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