Osmosis Eggsperiment

This website sponsored by Adam Equipment has a few very well developed lesson plans/activities for middle and high school students. There are several egg osmosis experiments available on-line. This particular document provides explicit teacher materials, model student answers and very detail instructions. There is also a student worksheet available (PDF) that can be printed downloaded and printed off. This experiment is quantitative and provides a wonderful opportunity the assess student performance via a formal lab report.

Weblink address (URL):

PDF

Standards & Objectives

Learning objectives:

Purposes:

To demonstrate the osmosis process.
To demonstrate changes in properties of matter.
To expose students to common measuring instruments used in the lab.

Lesson Variations

Blooms taxonomy level:

Applying

Extension suggestions:

Possible Extensions:

What would happen if the concentration of salt is changed? Will the mass of the egg increase or decrease? Why does this happen?
ANSWER: If the concentration of salt is increased, the concentration of water will decrease. If the concentration of salt is decreased, the concentration of water will increase. The mass of the egg will increase if the water concentration of the new salt water solution in the beaker is higher than the water concentration inside the egg. The mass of the egg will decrease if the water concentration of the new salt water solution in the beaker is less than the water concentration inside the egg. This happens because of osmosis, with the water flowing from an area of higher water concentration to an area of lower water concentration.
Redo the experiment by leaving the egg in the various solutions for 48 hours instead of 24 hours. Record mass and appearance changes on the observation chart. Discuss how doubling the time that the egg is in the different solutions caused changes in the egg and its mass.
ANSWER: The egg increases in size the longer you leave it in the water until the water concentration inside and outside the egg is equal.
While measuring mass changes every day, also record the egg’s position in the beaker during each of the four daily observation sessions. Explain how the daily changes in the egg’s size changed its buoyancy.
ANSWER: When the egg is placed in the vinegar, it sinks to the bottom with one end tilted up. As the vinegar reacts with the eggshell, bubbles surround the egg, causing it to float. When the egg is placed in the salt water, it sinks to the bottom of the beaker again, since it is more dense than the salt water solution. The egg floats in the corn syrup because the corn syrup is more dense than the egg. At the end of the experiment, the egg sinks again when it is placed in the fresh water.
Along with recording the mass of the egg on a daily basis, also measure the remaining volume of solution after the egg has been removed from the beaker. Create a chart to show daily egg mass changes and daily beaker solution changes. Discuss your observations and explain why these changes occurred.
ANSWER: Sample results for daily volume changes of the various solutions in the beaker:

Helpful Hints

What yoy need:

400mL beaker
graduated cylinder
one raw (extra-large or jumbo) egg, shell intact
200mL white vinegar
200mL (light) corn syrup
400mL room temperature tap water, divided
20g salt
small shallow dish (petri dish, culture dish, foil cupcake cup)
eighting paper (or filter paper)
triple beam or balance

References

Contributors:

Jenise Gordon

Originator:

Ayers Institute for Learning & Innovation