Stage 6 Biology: Patterns in Nature
Student: __________________ Date: ___________
First Hand Investigation: Surface area and rate of reaction
DOT point: perform a first hand investigation to demonstrate the relationship between
surface area and rate of reaction
Aim: To demonstrate the relationship between surface area and rate of reaction
Background Information:
In this experiment using antacid tablets and HCl, we simulate the conditions of digestion in
mammals. The antacid tablet represents the ‘food’ and the HCl represents a digestive
chemical. When an antacid tablet comes in contact with acid it reacts with it, producing
carbon dioxide bubbles, water and salt. The stomach of mammals naturally secretes HCl to
provide the correct environment for stomach enzymes to work. If too much acid is
secreted, digestive discomfort (heartburn) results. Antacid tablets are usually taken to
relieve digestive discomfort.
Safety: Avoid contact with skin or eyes with acid. Wear safety glasses. If there is contact,
rinse well with cool running water.
Materials:
 3 test tubes
 Test tube rack
 3 antacid tablets
 30-50mL dilute HCl
 2 spatulas
 stopwatch
Procedures:
1. Place a whole antacid tablet, a tablet broken into quarters and a crushed tablet into
three separate test tubes.
2. Pour the same amount of HCl into each test tube. (pour enough so that the whole
tablet is covered)
3. Use the stopwatch to measure how long each test tube fizzes, until the tablet is
completely dissolved.
4. Record your results in a table
5. Write a conclusion for this experiment
Results:
Tablet Time (seconds)
1
2
3
Stage 6 Biology: Patterns in Nature
Student: __________________ Date: ___________
Conclusion:
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Discussion:
1. Identify the dependent and independent variables in this experiment
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2. Describe all other variables that were kept constant
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3. What is meant by the rate of a reaction? Explain why a stopwatch was needed.
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4. What pattern or trend could you identify in the rate of reaction related to the surface
area of the antacid tablets?
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5. Explain why you belch after taking an antacid tablet. Give a reason why taking an
antacid tablet may relieve digestive discomfort.
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Stage 6 Biology: Patterns in Nature
Student: __________________ Date: ___________