Measuring the rate of a chemical reaction

Aim - to measure the influence of particle size of solid reactants on the rate of reaction.

Method - Using a mortar and pestle crush some calcium carbonate chips.
Weigh 20.0g of crushed CaCO3 into a 50 mL beaker.
Using a measuring cylinder, pour 20ml of 2.0 M HCl into the 50.0 mL beaker with the chips and place it onto an electronic balance. Quickly press the tare button to zero the display

Record the total mass lost over time in an appropriate table.

Plot a graph of the total mass loss versus time.

Consider the video on the right. It shows crushed marble chips reacting with 20.0 mL of 2 M HCl.

Use the information depicted in the video to create a table of data and a graph of total mass loss vs time.

 

 

Using some larger, uncrushed calcium carbonate chips. Repeat the steps above.
Weigh 20.0g of CaCO3 chips into a 50 mL beaker.
Using a measuring cylinder, pour 20ml of 2.0 M HCl into the 50.0 mL beaker with the chips and place it onto an electronic balance. Quickly press the tare button to zero the display

Record the total mass lost over time in an appropriate table.

 

 

Plot a graph of the total mass loss versus time.

Consider the video on the right. It shows uncrushed marble chips reacting with 20.0 mL of 2 M HCl. Use the information depicted in the video to create a table of data and a graph of total mass loss vs time.
Time (sec)

Total mass lost
(large chips) (grams)

 Total mass lost
(crushed chips)(grams)
     
     
     
     
     
     
     
 

Plot the results on an appropriate set of axis.

Answer the questions below only after you have conducted your own investigation.
1) What is the total mass lost after 30 seconds from both beakers?
2) Would you expect that, over time, both beakers would lose the same mass? Explain.
3) Is this what is observed?
4) What can you say about the relationship between rate of reaction and surface area of reactants.
5) Explain your answer to 4 above with reference to the collision theory.

6) Using the relationship, you have found during this activity, between surface area and rate of reaction explain the ignition of fine, carbon based, powders, as shown on the video on the right.

7) What is the dependent and independent variables

8) The independent variable is shown on the

9) The dependent variable is shown on the

Challenging questions
1) The reaction between calcium carbonate and hydrochloric acid is represented by the equation below.

2HCl(aq) + CaCO3(s) --> CaCl2(aq) + H2O(l) + CO2(g)
How do you account for the mass loss measured?
2) Click to see a 120kb video of carbon dioxide being poured into a beaker with a lit candle. What two properties of carbon dioxide gas are obvious from the video?
3) If carbon dioxide gas sinks to the bottom of its container why do we measure a mass loss? Refer to the kinetic theory of gases.
4) In what other way can we collect the carbon dioxide gas evolved and therefore measure the rate of reaction? Click to see a possible set up.
5) Why is the total mass loss of the finely ground powder less than the large chips of calcium carbonate?
**Hint you will need to be familiar with chemical equilibrium systems. This reaction is exothermic.

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