Part 3 - potato osmosis experimentDiffusionOsmosissolventsolute Molecules are constantly in motion as a result of a cell's stored kinetic energy, which causes them to bump into each other and move in random new directions

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Part 3 - potato osmosis experimentDiffusionOsmosissolventsolute

Molecules are constantly in motion as a result of a cell's stored kinetic energy, which causes them to bump into each other and move in random new directions. is the movement of molecules from an area of where there are many (high concentration) to an area where there are fewer (low concentration). is the diffusion of water through a semipermeable membrane. It is important to remember that a semipermeable membrane allows the (usually water) to pass through, but restricts the movement of a (a thing dissolved in the solvent). Water will move across a semipermeable membrane from an area of lower solute concentration to an area of higher solute concentration.

When each side of a membrane has equal solute concentration, the solution is said to be isotonic and water molecules will be equally likely to move in both directions across the membrane. If a solution is hypertonic relative to a cell, there is more solute outside the cell than inside the cell. Hypertonic solutions cause water molecules to move out of the cell and into the region of higher solute concentration. Conversely, in hypotonic solutions there is a higher solute concentration inside the cell than outside, and water molecules move into the cell. Whenever possible, water will always move from an area of higher water concentration and lower solute concentration to an area of lower water concentration and higher solute concentration.

Watch this quick video for a review of solution concentration and its impact on Osmosis.

In this activity, we are going to explore osmosis by looking at a dataset produced with a classic classroom experiment. The experiment uses pieces of potato that are placed in six different solutions of water each with a different solute concentration. The solute is the carbohydrate sucrose and the concentrations are measured in units of molarity. The solutions range from no solute to a high concentration of solute and are 0.0 (distilled water with no solutes), 0.2, 0.4, 0.6, 0.8 and 1.0 molar sucrose.

Pieces of potato are cut to similar sizes, weighed, and then placed in one of the six solutions overnight. The next day, the potato pieces are removed from the solutions, blotted dry, and their final masses are recorded.

Watch this short video that outlines how this osmosis lab was conducted, then you will look at the data collected from this lab and answer the questions below. (You will not be conducting the lab, but you will be able to analyze data collected following the same procedures.)

Questions

Before you look at the data from the potato experiment below, let's make some predictions from your understanding of the experiment and from osmosis. Do you expect a higher increase in mass in low or high concentrations of sugar water? Explain why using your understanding of osmosis & using the appropriate terms - hypertonic, hypotonic & isotonic