Saltwater vs Freshwater Experiment

Saltwater vs Freshwater Experiment

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Saltwater vs Freshwater Comparison

Saltwater and freshwater are constantly mixing and interacting in estuaries. An estuary is an area where a freshwater river or stream meets the ocean. In estuaries, the salty ocean mixes with a freshwater river, resulting in brackish water. Brackish water is somewhat salty, but not as salty as the ocean. Water continually circulates into and out of an estuary. Tides create the largest flow of saltwater, while river mouths create the largest flow of saltwater, while river mouths create the largest flow of freshwater. When dense, salty seawater flows into an estuary, it has an estuarine current. High tides can create estuarine currents. Saltwater is heavier than freshwater, so estuarine currents sink and move near the bottom of the estuary.

In this activity, you will analyze the density of saltwater and freshwater. Through this experiment, you will be able to simulate as well how saltwater and freshwater mix with their varying density.

Saltwater vs Freshwater Experiment Learning Objectives:

At the end of this Saltwater vs Freshwater Experiment laboratory activity, students are expected to:

  • Describe density of freshwater and saltwater by observing how objects float or sink in it
  • Describe the movement of saltwater and freshwater

Saltwater vs Freshwater Laboratory Proper:

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Saltwater vs. Freshwater Lab Materials:

Each group needs the following:

  • 2 identical clear plastic boxes
  • 1 clear plastic jar
  • 3 liters of water
  • a cup of salt
  • spoon
  • food coloring – blue and yellow
  • Slices of vegetables such as celery, broccoli, snow peas
  • Rags for cleaning up

Saltwater vs Freshwater Activity Procedure:

  1. Fill each clear plastic box with 1 liter of water
  2. Put 3 drops of blue food coloring in the first box with water. This will be your freshwater
  3. Put 3 drops of yellow food coloring in the second box with water. Add a cup of salt and stir it very well. This will be your saltwater
  4. Put several slices of vegetables in each water sample. Observe whether the vegetable slices sink or float in each water sample.
    Saltwater vs Freshwater Experiment
  5. Remove the slices of vegetables in each water sample. Pour the freshwater sample in a clear plastic jar.
    Saltwater vs Freshwater Experiment
  6. Slowly pour the freshwater sample to the saltwater sample. Observe what happens to the water. In the box below, draw what is formed in the middle of the container upon mixing two water samples.

Data and Results

Draw a pie graph that shows the water distribution on Earth.

Discuss the following with your students:

  1. Define density and buoyancy.
  2. How are buoyancy and density related to one another?
  3. In which water sample did vegetable slices float? Why do you think the result is such?
  4. Why is saltwater denser than freshwater?
  5. Describe what happened when saltwater was mixed with freshwater. Provide an explanation on what was formed when saltwater and freshwater meet.
  6. Based on the activity, how will you differentiate saltwater and freshwater?

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