Fun with an Egg and Osmosis
Osmosis is a very important process for moving WATER through membranes in and out of cells. We are going to take an egg and immerse it in Acetic acid for a day. The acid will remove the shell, providing a natural cell membrane around a giant cell with which to experiment. We will observe when water moves inside and outside of the egg, which is determined by the concentrations of water in and out of the cell. Read the ENTIRE LAB, and then write 2 hypotheses.
Write EVERYTHING in your lab book. This should include: Prelab, Lab Materials, Methods (procedure), Data (Data Table & Observations), Interpretation, and Conclusion.
Hypothesis 1: After removal of the shell, what will be the direction of osmosis, into or out of an egg when placed in vinegar? The egg is 8% dissolved substances and 92% water. Vinegar is 5% solute and 95% water. Explain your reasoning.
Hypothesis 2: What will be the direction of osmosis, into or out of an egg when placed in corn syrup? The syrup is 60% solute and 40% water. Explain your reasoning.
LAB: Experimental Design
Clear plastic cup
1. Measure the mass, volume, and circumference of an egg. How you do it is up to you. Record observations in data table.
2. Set the egg in a plastic cup and pour vinegar over the egg until it is covered with about 3 cm of liquid. Cover the cup with saran wrap.
3. Observe any chemical reactions taking place and record these in the data table. Place the beaker and egg in your drawer for 24 hours.
1. Observe any changes to the egg and record.
2. Carefully remove the egg, rinse and dry it. Measure the mass, volume, and the circumference again. Record data and observations.
3. Pour on the vinegar and rinse the cup. Add 1 inch of corn syrup to your cup then add the egg. Cover and leave in your drawer for 24 hours.
4. Answer questions 1-3 in the interpretations.
1. Carefully remove the egg and measure the mass, volume, and circumference again. Record data.
2. Observe any changes to the egg and record the data and observations in the table. Be sure to fill in each box in the table. Label the units in parentheses.
Data Continued: Describe qualitative changes in the egg.
1. After the shell was removed when immersed in vinegar, in which direction did the water move, into or out of the cell?
2. Use tonicity terms to compare the egg and the vinegar when initially placed together.
3. Explain the direction of the water’s movement in terms of the concentration of water, both in the egg and in the vinegar.
4. After immersion in the syrup in which direction did the water move, into or out of the cell?
5. Use tonicity terms to compare the egg and the syrup when initially placed together.
6. Explain the direction of the water’s movement in terms of the concentration of water both in the egg and in the syrup.
7. For centuries, salt and strong sugar solutions like corn syrup have been used to preserve foods and protect them from being colonized by living bacteria and fungi. This was long before refrigeration was invented. Why do these solutions defend against spoilage so effectively? The egg was a model of all cells including bacterial and fungal cells, which spoil food. What would happen to bacteria and fungi which land on food treated by these substances?
Restate your hypotheses and tell if they were supported, contradicted, or not supported.