Temperature and Osmosis Vaughan Andrews Jordan Cohen Anthony Webb

Purpose To determine how temperature effects osmotic rate HYPOTHESIS- If a potato is placed in four 4% salt solutions at different temperatures, then the potato in the coldest solution will lose the most mass

Background Osmosis is the diffusion of water through a membrane by passive transport Water moves from a hypotonic solution to a hypertonic solution Hypotonic solutions have a lower concentration of a solute than a hypertonic solution A potato is considered hypotonic when related to a 4% salt solution of water

Procedure 1. Obtain material – 3 plastic cups and 1 500ml beaker – 4 potato cores – 1 hot plate – Salt – 1 100ml graduated cylinder – Stirrer – Thermometer – Stopwatch 2. Add four grams of salt to each cup or beaker 3. Add 100ml of water to the four grams of salt in each container; stir until dissolved 4. Place the beaker on the hot plate and bring to a boil, place one plastic cup in the refrigerator, place one plastic cup in the freezer, and leave one plastic cup in the room. 4.Weigh the potato cores on a triple beam balance and record 5. Add a potato core to each container, let them sit for 30 minutes. 6. Remove the potato from the water and dry with a paper towel 7. Weigh the potato cores again on the triple beam balance and record. 8. Record the change in mass between the original potato core and the potato core after it’s time in the water

Data 4 degrees15 degrees20 degrees74-98 degrees Original Weight2.7 g2.9 g2.6 g2.8 g Final Weight2.3 g2.4 g2.1 g2.8 g Change in-.4 g-.5 g 0 g Percent Change-14.81%-17.24%-19.23%0%

Conclusion As temperature increases, osmotic rate increases because of the high kinetic energy of the water molecule, allowing them to move quicker through the plasma membrane. If the temperature gets to high, the cell membrane begins to denature because of the aquaporins in the membrane. This would stop osmosis because the water could not pass through the membrane. The salt solution was hypertonic compared to the potato so water diffused out of the potato causing it to lose

Sources of Error A. The temperature of the boiling water varied greatly, from B. As the water boiled off, the salinity rose because there was less water for the same amount of salt. To fix this, we added extra cold water, which messed with the density and temperature. C. The water temperatures were not consistent with the containers (fridge, freezer, boiling), we should have prepared the water before, to keeping the temperatures consistent. D. The water in beaker three was spilled during the experiment, so we quickly added more water, probably skewing our results.