Question

Four eggs are stripped of the shell and weighed. Each egg is put into a solution with a different concentration of salt measured in molarity (M). After 8 hours of soaking, the eggs are weighed again and the percent weight change was calculated and graphed (shown below). Egg Graph 15 10 2.5 3.5 3 -10 -15 -20 Solution Salt Concentration (M) 1. Is the graph title appropriate? If no, please suggest an improved title. (1 pt) 2. Identify the dependent variable in this example. (1 pt) 3. Indicate the units used to measure the independent variable. (1 pt) 4. In the experimental data recorded, the egg soaked in 0.5M solution resulted in how much weight change? (1 pt) 5. If an egg was put in a 1.0M salt solution, predict the weight change using the best fit line. (1 pt) What is the range of salt concentrations that would be considered hypertonic to the egg? (2 pts) 6.

Answer 1

This is a very simple experiment to understand the science of osmosis and semi-permeable membranes. Egg has a semi-permeable membrane underneath its hard shell. Here the egg shells are removed and the egg is put into solutions of different solute concentrations. The membrane in the egg is said to be semi-permeable because it allows only the solvent molecules ie here in this case water molecules to pass through it. It prevents the passage of other solutes and larger molecules like proteins through it. This movement of water molecules through the semipermeable membrane from a solution with high concentration of water to a solution with less concentration of water is called osmosis. It happens till the concentrations of water in both the solutions are equal ie when they reach equilibrium. Diffusion is also similar but refers to any substance spreading from a higher concentration to a lower concentration without a membrane.When the eggs are placed in hypotonic solutions osmosis causes the water molecules to enter the egg through the semipermeable membrane it has. This happens because the solution has more water (or less solutes) in it than in egg. Hence the weight of egg increases. When the egg is placed in hypertonic solutions osmosis causes water to move out of the egg through the membrane and the egg shrinks. This happens because hypertonic solutions has less water (or more solutes) than egg. Keeping these background information the questions are answered.

1.The present title “egg graph” is not appropriate. Better titles would be “% weight change of egg with concentration of solution” or “Egg osmosis experiment graph”

2.The dependent variable in this experiment is the Weight Change % in y-axis since this parameter is dependent on the concentration of the solution in which it is dipped.

3.The independent variable is solution salt concentration given in x-axis and the unit is M

4.Egg soaked in 0.5M solution resulted in 5% weight gain for the egg

5.If the egg was put in 1M salt solution from the best fit line in the graph it would have a weight gain of ~2%

6.The range of the salt concentration considered to be hypertonic to the egg would be from ~1.2M to 3.5M when the eggs shinks and losses weight when dipped in them.