Lab 5
19
Lab 5
Ocean Acidification
Description of the Lab
This lab is an introduction to ocean acidification. Students will review the
This lab will take approximately 2 hours.
Outline of Investigation
Exercise 1 – Solubility of Different Shell Types
Materials needed:
• distilled water
• 250 mL beakers (2)
• 100 ml beakers (6)
• Hot pads for handling glassware
• Forceps
• Mussel shells (or other adult bivalve or gastropod)
• Gloves
• Goggles
Note: Small pieces of coral are often available in pet stores that carry Hermit crab
supplies. Often bags labeled ‘Puka Shell Mix’ will have many tiny shells and small
pieces of coral. If you have limited time, soak bivalve shells in a 10% bleach solution
It is crucial that specimens are completely dry before you weigh them or you may record
increase in mass after the acid treatment. It is also important that coral and shells with
crevices be free of debris or you will get an unrealistic weight loss due mostly to the sand
or other debris being lost and not the acid dissolving the calcium carbonate.
Exercise 2 – The Effect of CO2 on pH
Materials needed:
• distilled water
• 250 mL beakers (2)
• Goggles
Laboratory Materials and Equipment for Student Use
Materials and
Equipment
Per Student
Per Pair of
Students
Per Lab
Group
Per Room
Distilled water
300-400 mL
250 mL beakers
2
100 ml beakers
6
Graduated
cylinders
2 (50 mL)
Clean, unused
drinking straws
2-4
Dropper bottle
Bromothymol
blue (or Phenol
red, a pH
indicator)
1
(sodium
hydroxide)
(household
vinegar)
places in
grams)
Hair dryer or
drying oven
1-2
Hot plate
1
Hot pads for
handling
glassware
1
bivalve or
gastropod),
clean and dry
(clean and dry)
Paper towels
6-8
hammer
1
Grease pencil
1
Goggles
1
Gloves
1
Preparation of Laboratory Materials and Reagents
0.4% NaOH solution
Answers to Questions for Lab 5
1. Did the exposure to the 5% acetic acid affect the coral and the mussel shells equally?
2. What effect did the temperature of the 5% acetic acid have on the outcome?
Lab 5
23
3. What sources of error are present in your data (e.g., when you put the coral pieces in
the liquid did the procedure dislodge any sand)?
Initial shell or coral mass may have included material that was not dissolved by
4. Many molluscs secrete a proteinaceous layer called a periostracum, as a protective top
coat on their shells. Shell collectors often remove this layer by soaking the shell in
household bleach. What effect do you think it would have on your results if you
removed the periostracum and then exposed the shell to acetic acid?
5. Do you think that all calcium carbonate organisms will be affected equally by the
drop in ocean pH? Explain your answer.
No, different species and different lifestages make their shells or other hard
6. In exercise 2, based on the number of drops you had to add to neutralize the solution
did each member of your group blow the same amount of CO2 into the water? What
variables would affect CO2 output person-to person?
Answers will vary but for example, an increase in respiration would tend to