The movement of molecules from an area of greater concentration to an area of less concentration is called Diffusion. Osmosis is the diffusion of water through a selectively permeable membrane from an area with greater concentration of water to an area with less concentration. A Hypertonic Solution is a solution of a higher concentration of solutes and a smaller concentration of water molecules than another solution. However, an Isotonic Solution is a solution that contains an equal concentration of solutes and of water molecules, the same as another solution. A solution that contains a lower concentration of solutes and a higher concentration of water molecules than another solution is called a Hypotonic Solution. A cell that has a Selectively Permeable Membrane has a plasma membrane that allows certain substances to pass through more readily than others.
From this I have come up with a hypothesis of what will happen with the 2 bags. The one containing fresh water and put into salt water will lose weight, based on a Hypertonic Solution stated above. However, the bag containing salt water and put in fresh water will gain weight based on the Hypotonic Solution also stated above.
1.First we folded one side of the membrane-like bag we were given and tied it shut over the folded part.
2.Then we filled it 2/3 full of freshwater and tied the other end shut, and weighed it.
3.Next we weighed it and put the bag into the saltwater.
4.After that, we did Steps 1, 2, and 3, except, we filled the bag 2/3 full with saltwater, weighed it, and put it into freshwater.
5.After about 30 minutes we went back and took both bags out and weighed them.
Before we placed the bags in the salt and fresh water we weighed them. The bag filled with freshwater weighed 18.3 grams and the bag containing the saltwater weighed about 23.9 grams. After they had soaked in their rightful waters for about half an hour we weighed them again. The freshwater weighed 16.2 grams and had sustained an 8.9% decrease of weight. The saltwater weighed 25.1 grams and had attained a 9.5% increase of weight.
Well, the freshwater bag lost weight through the Hypertonic Solution theorem. Because there was no salt in it, the fresh water left the cell to mix with the salt outside its cell. No salt molecules could get in, in return. The saltwater bag had gained weight during the 30 minute time period. It had done this through the Hypotonic Solution theorem. The freshwater outside the bag(cell) had entered it because there weren’t many water molecules inside the cell. Causing the bag filled with saltwater to gain weight.