1. Lab Tomorrow: Osmosis & Diffusion Do Now: A student wants to know if water molecules can fit through the microscopic holes in a plastic bag. They fill a bag with a concentrated sugar solution, record its mass, and then place it in a beaker of pure water. The student’s hypothesis is that water will move into the bag by osmosis. 1.Write a prediction the student could make to test their hypothesis. 2.What is the dependent variable of the experiment? 3.What kind of solution is the bag in? (hypertonic, isotonic, or hypotonic)

2. About that lab : We will be looking for evidence of 2 processes: osmosis and diffusion

3. Osmosis How can we tell if water enters or leaves the bag? The solution inside is a concentrated starch solution. What do you hypothesize?

4. Diffusion We will also be able to tell if any molecules are able to diffuse through the bag. When starch and iodine mix, they make a purple color. Since starch starts inside the bag, and iodine on the outside, we will be able to tell what is moving where.

5. Where are the three chemicals going to move? How will we know?