Simple Salinity Lab

Marine BiologyMr. Robinson

Materials

• 4 test tubes• 4 pipettes (droppers

may be used)• Red food coloring• Blue food coloring• Green food coloring• 4 beakers• Sea salt

• Test tube holder• Tap water as required• Salt water (prepared

by teacher)• 3 Erlenmeyer flasks

for mixing liquids (Teacher use only)

Observation #1

• What happens when the food coloring is dropped into the regular tap water?

• What does this observation tell you about the density of the food coloring when compared to the tap water?

• When you check back later how much diffusion has taken place?

What is density?

Observation #2

• What happens when the food coloring is dropped into the salty water?

• What does this observation tell you about the density of the food coloring when compared to the salty water?

• When you check back later, how much diffusion has taken place?

Part One

• Fill the test tube ½ full with clear tap water• Fill the transfer pipette with green very salty

water• Carefully place some very salty water into the

beaker with the tap water and record your observations.

Part Two

• Fill the test tube ½ full with clear salt water• Fill another transfer pipette with blue tap

water• Carefully place some blue tap water into the

test tube with the clear salt water and record your observations.

Part Three - A

• Fill the test tube ½ full with very salty green water

• Using a pipette, carefully place clear tap water into ¼ of the test tube on top of the very salty green water and record your observations.

• Without emptying the test tube, continue to Three – B…

Part Three - B

• Making sure that your pipette is clean, fill the pipette with slightly salty red water

• Carefully place the pipette INTO the layer of very salty green water and squeeze out a drop of slightly salty red water. Record your observations.

• Place your thumb on top of the test tube and shake it. Record your observations.

Part Four

• See if you can make a three or four layer column of water in your test tube.

• Explain how you decided the order in which to put the different salinities into the test tube?

• Record your observations.