Effect of Surface Area on Rate of Reaction

This practical lesson covers:

  1. The effect of changing the surface area of marble chips on the rate of reaction between marble chips and dilute hydrochloric acid
  2. The effect of changing the concentration of hydrochloric acid on the rate of reaction between marble chips and dilute hydrochloric acid

Investigating the effect of surface area on the rate of reaction


Aim

To investigate what effect the concentration of hydrochloric acid and the surface area of marble chips have on the rate of reaction when marble chips react with hydrochloric acid.

Background information

The rate of a chemical reaction depends on factors like concentration and surface area. In this practical, you will investigate the effects of varying hydrochloric acid concentration and marble chip surface area on the rate of reaction between hydrochloric acid and marble chips (calcium carbonate). You will measure the rate of reaction by recording the decrease in mass due to the release of carbon dioxide gas.

What is the effect of changing the surface area of marble chips on the rate of reaction?

no effect on the rate of reaction

decreases the rate of reaction

increases the rate of reaction

0

/

1

What is the effect of changing the concentration of hydrochloric acid on the rate of reaction?

increases the rate of reaction

no effect on the rate of reaction

decreases the rate of reaction

0

/

1

What is the chemical formula for hydrochloric acid?

HCl

0

/

1

What is the effect of increasing the surface area of the marble chips on the rate of reaction?

increases the rate of reaction

no effect on the rate of reaction

decreases the rate of reaction

0

/

1

How do you measure the rate of reaction in this experiment?

by recording the decrease in mass

by recording the change in colour

by recording the increase in temperature

0

/

1

Investigating the effect of surface area on the rate of reaction


Aim

To investigate what effect the concentration of hydrochloric acid and the surface area of marble chips have on the rate of reaction when marble chips react with hydrochloric acid.

Background information

The rate of a chemical reaction depends on factors like concentration and surface area. In this practical, you will investigate the effects of varying hydrochloric acid concentration and marble chip surface area on the rate of reaction between hydrochloric acid and marble chips (calcium carbonate). You will measure the rate of reaction by recording the decrease in mass due to the release of carbon dioxide gas.

Equipment

  1. 250 cm3 conical flask
  2. Cotton wool
  3. Digital mass balance
  4. Measuring cylinder
  5. Timer
  6. Hydrochloric acid (0.25 mol/dm3, 0.5 mol/dm3, 0.75 mol/dm3)
  7. Marble chips (various sizes)

Method 1 - Investigating the effect of changing concentration

  1. Add 100 cm3 of 0.25 mol/dm3 hydrochloric acid to the conical flask. 
  2. Place the conical flask on the balance and push the cotton wool into the opening. Record the mass. 
  3. Leave the conical flask on the balance to allow the mass to be measured throughout the investigation. 
  4. Add the marble chips to the flask, replacing the cotton wool as soon as it is added. Start the timer immediately. 
  5. After 30 seconds record the new mass of the conical flask. 
  6. Repeat steps 1-6 with increasing concentrations of hydrochloric acid, ensuring the size of marble chips remains constant.
  7. Calculate the rate of reaction for each of the experiments. Compare the results for the different concentrations of acid. 

Method 2 - investigating the effect of changing surface area

  1. Take the sample of marble chips with the smallest surface area. Measure the mass of the chips.
  2. Place 100 cm3 of hydrochloric acid in the conical flask. Make a note of the concentration of acid as this must be kept the same for each test.
  3. Place the conical flask on the balance and push the cotton wool into the opening. Measure the mass of the conical flask containing the acid.
  4. Carry out the experiment on the digital mass balance so that the mass can be measured throughout the experiment.
  5. Add the marble chips to the flask, replacing the cotton wool as soon as it is added. Start the timer immediately.
  6. After 30 seconds record the new mass of the conical flask.
  7. Repeat steps 2-6, increasing the surface area of the marble chips. Make sure the mass of each sample is the same.
  8. Calculate the rate of reaction for each of the experiments. Compare the results for marble  chips with different surface areas.

Safety

  1. Hydrochloric acid is corrosive when concentrated. Use dilute solutions to prevent harm. Wash hands if in contact with acid.
  2. Take care when handling glassware. Clear up any breakages immediately.