How changing concentration affect rate of reaction between hydrochloric acid and calcium carbonate?

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How does changing concentration affect the rate of reaction between hydrochloric acid and calcium carbonate?

In my experiment, I am aiming to find out how and why different concentrations of hydrochloric acid affect calcium carbonate chips.

CaCO3 + 2HCl → CaCl2 + CO2 +H2O

Apparatus List

  • Side arm test tube (10ml)
  • Hydrochloric acid
  • Distilled water
  • Calcium Carbonate Chips/powder (3 chip sizes)
  • Delivery tube
  • Water
  • Bung
  • Measuring Cylinder (10ml)
  • Measuring Cylinder (100ml)
  • Container
  • Stopwatch
  • Test Tube Rack
  • Weighing Scales (2 d.p)
  • Clamp
  • Stand

Here is how I set up my apparatus;

Method

  • I filled a container 2/3 full.
  • I filled a 100ml measuring cylinder with water and turned it upside down in the container and attached the other end of the cylinder to the clamp.
  • I put the test tube in the test tube rack and attached the delivery tube to side. I put the other end of the delivery tube in the upturned measuring cylinder.
  • I put 3 grams of medium sized marble chips (which I measured with a 2 decimal place set of scales) into the test tube.
  • I measured 2ml hydrochloric acid using a 10ml measuring cylinder into the test tube.
  • As soon as I had added the acid, I put the bung on the test tube and started the stopwatch. I measured the time taken to produce 10cm³, 30cm³ and 50cm³ gas.
  • I cleaned the necessary equipment.
  • I then repeated my experiment using different concentrations of acid, different volumes of liquid, collecting, different masses of chips, different size of chips, and repeated each experiment.

Results        

How my preliminary work will affect my plan

From my preliminary work, I am considering a number of points. The first is that I am going to use 10ml liquid in each test tube. I have decided this as I tested using 2ml of liquid but this made the reaction too slow to record the results even using 2 mol/dm³ acid. Secondly, I am going to collect 30cm³ gas. 10cm³ was too quick to collect my results from and 50cm³ was too slow. Also, I am going to use 2g marble chips because when I used 0.5g, it had only collected 7cm³ gas after 1 minute which is far too slow. When I used 5g and 10g I found that the reaction was too fast to accurately record results and also I wouldn’t be able to fit 10ml liquid in the test tube. In addition, I will be using the medium sized chips because powder was far too quick to record the results, the large chips were too slow as I only have a certain amount of time to collect all my results. Although there was only a small difference between the small and medium chips, I decided to used the medium chips as they give me slightly more time to record my results. I will be using a range of concentrations of acid in my experiment.  I have decided to use 1 mol/dm³ to 2 mol/dm³ as these results were collected in reasonable time. I tested 0.2 mol/dm³ but there was no gas collected after 2 minutes. Finally, I will be doing 3 repeats of all my results. This is because if I only have one result I cannot be sure it is accurate. Also if I have 2 results but they are not very close, I will not know which is the right one. However, if I have 3 results 2 compare, if I have 2 results close together then I can be quite sure that they are right and I can exclude the anomalous result from my averages.

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Prediction

I predict that if I increase the concentration of acid, the rate of reaction will increase. If I double the concentration of acid, the rate of reaction will double. This is because if I increase the concentration of HCl, the number of acid particles in a given volume increase which means an increase in a chance of collision between an acid particle and calcium carbonate and so an increased rate of reaction. If I double the concentration of acid, there will be double the number of acid particles in a given volume which means double the chance ...

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