Osmosis Lab

Definition of Osmosis WATER moves from an area of HIGH to LOW concentration.

Problem/Purpose What effect will distilled water and salt water have on the mass of a potato slice? Increase in mass – water going in Decrease in mass – water coming out

Research Background Knowledge Osmosis is the diffusion of water. Water moves from an area of high to low concentration. The size of the substance in relationship to the size of the openings (pores) in the membrane will impact diffusion/osmosis. Cells will either remain the same, swell or shrink as a result of osmosis.

Hypothesis The potato slice in the distilled water will increase in mass. The potato slice in the distilled water will decrease in mass. The potato slice in the salt water will increase in mass. The potato slice in salt water will decrease in mass. DON’T FORGET YOUR REASONING... YOUR “BECAUSE” STATEMENT.

Variables Independent What did we change? What experimental condition was under our control? Type of Water Dependent What are we measuring? What data we are collecting? Mass of the potato slice

The Experiment Control Group Did we have one? Potato slice placed in an isotonic solution No movement of water Potato in distilled water Experimental Group Potato in salt water

Constants What did we keep the same to control the number of variables introduced into the experiment? –The potato –Volume of liquid in Petri dish –Equipment as directed in “Materials” list –Method used to set up the experiment –Method used to collect data

The Data Type of Water Mass Before (grams) Mass After (grams) Difference in Mass (grams) % increase or decrease

% of Change (increase or decrease) Difference ÷ Mass Before × 100 Mass Before – 4 grams Mass After – 6 grams Difference in Mass – 2 grams 2 g ÷ 4 g = 0.50 × 100 = 50%