Part 1: U-Tubing Demonstration of Osmosis

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Osmosis Demonstrations

Part 1: U-tubing Demonstration of Osmosis

Background: Tubing is set up in the shape of a U. A selectively permeable membrane is placed in the center of the U-shape as drawn in the diagram above. Water is poured in at equal height. Solute and red dye are added to the left side of the U shape. What will happen to the level of water on each side of the tubing?

Directions: Fill in the rest of the hypothesis based on your knowledge of passive transport.

Hypothesis: If we add sugar molecules to the left side of the tubing, then water moves______because ______

______.

Directions: Draw what happened to the water levels observed below. Include an arrow to indicate which way the water moved.

Directions: Fill in the blanks below (word bank: High, low, solute, solution, left, right, selectively permeable membrane). Words will be used more than once.

The water moved to the ______side because there was greater ______in the ______on that side. Because there was greater ______and less water, the solution is referred to as ______. The high concentration water on the ______is referred to as ______because it has a greater concentration of water in the ______. Water passed through the ______because water went from ______concentration to ______concentration.

Part 2: Osmosis in an Egg

Background: The outer shell of an egg is removed so that the egg’s membrane is exposed. The egg’s membrane selectively allows materials to enter and leave the egg much like the membrane of a cell is selectively permeable. In this demonstration, one egg is placed in vinegar (weak acid with a high concentration of water), another is placed in distilled water, and a third egg is placed in maple syrup (high concentration of glucose).

Hypotheses: If we place one egg in vinegar, then the egg ______in size because ______

If we place one egg in distilled water, then the egg ______in size because

______

If we place one egg in maple syrup, then the egg ______in size because

______

Directions: Draw what the egg looks like for each of these conditions.

Solution / Drawing Before / Drawing After
Vinegar /
Distilled Water /
Maple Syrup /

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Directions: Fill in the blanks below (Word Bank: Increased, decreased, same, high, low, egg, solution). Words will be used more than once.

1.  The egg placed in vinegar ______in size because in osmosis, water moves from ______concentration to ______concentration until both sides have the ______concentration of water. There was a greater concentration of water in the ______compared to the ______so water moved from ______to ______.

2.  The egg placed in distilled water was the ______in size because in osmosis, water moves from ______concentration to ______concentration until both sides have the ______concentration of water. The egg had the ______concentration compared to the ______so water moved back and forth at the ______rate.

3.  The egg placed in maple syrup ______in size because in osmosis, water moves from ______concentration to ______concentration until both sides have the ______concentration of water. There was a greater concentration of water in the ______compared to the ______so water moved from ______to ______.