Diffusion is the movement of molecules from an area of high concentration to an area of low concentration. When the molecules are spread throughout an area equally, it is called equilibrium. Osmosis is the diffusion of water across a membrane. There are three different solutions in osmosis, and they are hypotonic, hypertonic and isotonic. Hypotonic is when water molecules move into the cell, hypertonic is when water molecules move out of the cell and isotonic is when water molecules move in and out of the cell at the same time, so the mass of the cell does not change.
Passive transport is the same thing as diffusion, which is the movement of molecules from an area of high concentration to an area of low concentration. Active transport is the exact opposite of passive transport. It is the movement of molecules from an area of low concentration to an area of high concentration. Active transport requires energy, but passive transport does not.
Question: How does the salt concentration affect the total change of the egg’s mass?
Hypothesis 1: If an egg is put in a 15% salt solution then the water would diffuse out of the egg and the mass of the egg would shrink because water moves from high to low water concentrations and would move to the area where the water has the lowest concentration gradient.
Hypothesis 2: If an egg is put in a 5% salt solution then the osmosis rate would be the same because the solution is isotonic and thus the mass would stay relatively the same.
Hypothesis 3: If there is no salt in the water then the egg will expand faster because there is no solute and the mass of the egg will increase due to how much water would enter through the egg’s membrane.
- Gather Materials
- Find the original mass of the eggs and record in grams
- Get masking tape
- Create labels for each of the three beakers with the type of solution
- Pour 150 mL of each solution in the corresponding beakers
- Place the eggs in each of the beakers
- Wait 10 minutes
- Record any changes throughout the experiment
- Spoon the eggs out
- Dry off CAREFULLY!!
- Find the new mass of each egg and record in grams
- Find the difference between the old weight and the new weight
- Record the difference in grams
Variables: The predicted independent variable is how much salt is in the water. The predicted dependent variable is the weight of the egg.
Control: The predicted control is water without any salt.
-Type of egg
-Amount of water
-Size of beaker
Type of Solution Original Weight (g) After Soaking Weight (g) Change (g)
0% Salt 91.83 92.97 +1.14
5% Salt 86.56 86.43 -0.13
15% Salt 91.3 89.85 -1.45
It was predicted that the mass of the egg in the 15% salt solution would shrink because water moves from high to low concentration, the mass of the egg in the 5% salt solution would stay about the same because the solution is isotonic and the concentration of water was the same in both inside and out of the cell, and the mass of the egg in the 0% salt solution would increase because there is no solute. The first hypothesis turned out to be correct, because the mass of the egg we tested decreased. The second hypothesis was also correct because the mass barely increased at all. The third hypothesis was correct as well because the mass increased. The egg’s mass that was in the 15% salt solution changed the most, the 5% salt solution changed the least, and the 0% salt solution was in between. These results occurred because of diffusion. The 15% was hypertonic because the water concentration was less outside of the cell than inside the cell and the water moved from inside the cell to outside of the cell, the 5% was isotonic because the water concentration was about the same inside and outside of the cell and the water moved in and out of the cell at the same time, and the 0% was hypotonic because the water concentration was greater outside of the cell than inside of the cell and the water moved from outside of the cell to inside of the cell. This would be three examples of passive transport, because there is no energy required to move from high water concentration to low water concentration. You could also call this facilitated diffusion. It is not active transport though, because active transport is water molecules moving from an area of low water concentration to an area of high water concentration and requires energy. An error that occurred in this experiment was one of the timers got paused, so the time wasn’t completely accurate to the second. Something that could be changed to improve this experiment is we could leave the eggs in the solutions longer so they have more time to change. We also could make sure the timers are started and stopped at the right times and not stopped in the middle of timing.