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Pre-Visit
Activities : Water Quality
Procedures
MAIN
| OBJECTIVES | STANDARDS
| BACKGROUND | PROCEDURES | ASSESSMENT
| RESOURCES
Materials
Part 1
Mini-lab 1
- pH paper
- water
- lemon
juice
- vinegar
- soda
- milk
- baking
soda
- bleach
- shampoo
- orange
juice
- detergent
- cups or beakers
- safety goggles
Mini-lab 2
- glass beakers
- salt
- water
- pH paper
- hydrometer/refractometer
- thermometer
- dissolved oxygen kit or meter
- hot plate
- safety goggles
Part II
- pH paper
- hydrometer or refractometer
- thermometer
- dissolved oxygen kit
Top
Procedure
Part
1
Discuss
water quality with your students. Ask them what they think water
quality is. Teachers may want to use two photographs, one of
a polluted stream and one of a healthy stream. Have students
discuss factors that influence water quality. In
the discussion focus on temperature, pH, dissolved oxygen and
salinity as some of the factors that can be measured to determine
water quality.
Mini-lab
1
- Ask students if they’ve heard of pH. Introduce the terms
acid, base and neutral. Discuss the pH scale.
- Have students determine the pH of five household products.
You may choose to use water, soda, vinegar, lemon juice, shampoo,
milk, bleach, orange juice, detergent, baking soda or any
other product that would be acidic or basic. (Mix baking soda
and water to create a solution.)
- Each group of students should be given five beakers containing
the household products listed above. They should determine
the pH of each item. Have them record their data in their
journal. They should determine if each substance is an acid
or base. Remind students to wear safety goggles.
Mini-Lab 2
- Discuss salinity. Ask students what salinity is, what bodies
of water should have greater salinity and where the salt comes
from.
- Have students measure the salinity of two water samples.
To create these samples, add salt to a beaker of water. Mix
well. To the second beaker add only water. Have students determine
the salinity using a hydrometer or refractometer. These tools
can be ordered from a scientific supply company. Students
should also measure the temperature, dissolved oxygen and
pH of each sample.
- Next, heat the water samples using a hot plate. Allow evaporation
to take place. After the sample has cooled, have students
measure the salinity, temperature, dissolved oxygen and pH
again. Record results and discuss why changes may have occurred.
Part II
Using information learned during the mini-labs, have
students design an experiment to determine the water quality
of a local body of water. They may use a drainage ditch,
stream, river, pond, etc. Students should include temperature,
pH, salinity, and dissolved oxygen. Other factors such as
turbidity and stream velocity may also be included.
Top
Follow-up Questions
- Is pH affected by temperature or the salinity of the
water? If so, explain your answer.
- How does temperature affect dissolved oxygen?
- Using the data collected on the local body of water,
describe factors that may affect the parameters you tested.
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