DIFFUSION DRY LAB I. Analyzing a Laboratory Investigation INTRODUCTION - Background: Define Diffusion: 6th hour Bio did an experiment to find out how concentration and temperature effect the rate of diffusion. Use their data in the chart to analyze the investigation. Problem: What effect does an increase in concentration and temperature have on the rate of diffusion? METHOD- Materials: laboratory balance glass-marking pencil weighing paper hot plate spatula graduated cylinder potassium permanganate crystals ice cubes 6 250-ml beakers clock or watch with second hand Procedure: 1. Fill each beaker with 200 ml tap water. 2. Change the temperature as noted in the table. 3. Add the amount of potassium permanganate crystals as noted in the table. 4. DO NOT STIR. 5. Time how long it takes the substance to completely diffuse. 6. Record the time on the lab sheet. Amount of Potassium Beaker Change Temperature permanganate A - 5g B - 10g C Add 4 ice cubes 5g D Add 4 ice cubes 10g E Heat until water boils 5g F Heat until water boils 10g
DATA AND CALCULATIONS- Data Table: (In their notebooks) Summarized Data: High/ Low Concentration? Hot/ Medium/ Cold Temp.? Beaker with fastest diffusion - Beaker with 2nd fastest - Beaker with 3rd fastest - Beaker with 3rd slowest - Beaker with 2nd slowest - Beaker with slowest diffusion - F E B A D C 1. What effect did the concentration of potassium permanganate have on the rate of diffusion - in beakers A & B? - in beakers C & D? - in beakers E & F? 2. What effect did the concentration of potassium permanganate have on rate of diffusion in general? 3. What effect did temperature have on rate of diffusion? 4. Which set of beakers (A & B, or C & D, or E & F) served as the control in this investigation? Explain. 5. Why did the potassium permanganate in beaker F diffuse fastest? 6. What would have happened in beaker D if the potassium permanganate concentration had been increased? NOTE: On the next page, the directions above #6, 7, 8, should read...hypotonic, or a hypertonic solution OUTSIDE the cell...
Analyzing an Investigation The cellophane bag is a semipermeable membrane. The beakers are set up as pictured below. After several hours, a small amount of water is taken from each beaker and tested for the presence of starch. or sugar. Presence of STARCH: Iodine added will change color from amber to black. Presence of SUGAR: Benedict s solution added and heated will change from blue to orange or red. Results: Beaker A- water remained amber when iodine was added. Beaker B- water became red when Benedict s solution was added & heated. Cellophane bag with starch solution in it Cellophane bag with glucose solution in it water in beaker A water in beaker B QUESTIONS: 1. Did the water in beaker A contain any starch? 2. Did the water in beaker B contain any sugar? 3. To which substances, if any, are the cellophane bags permeable? 4. Will there be an increase in the volume of liquid in either bag? If so, which one? 5. Distinguish between endocytosis, exocytosis, pinocytosis, & phagocytosis.
OSMOSIS PACKET Period Name EGG DEMO LAB This experiment uses decalcified eggs, which are raw eggs soaked in vinegar for 24-36 hours. This breaks down the shell so that only the membrane is left. Since an egg is essentially a cell, this may be a selectively permeable membrane. In osmosis, water moves from high concentration to low concentration through a selectively permeable membrane. The question is, if a decalcified egg is put into corn syrup, which has a very high sugar concentration, what will happen to the egg? Hypothesis: When a decalcified is soaked in corn syrup, the egg s mass will, because Data: Before soaking After soaking Mass of Egg (g) in corn syrup Mass of Egg (g) in egg whites & yolks Calculations: %Change for egg in corn syrup = % Change for egg in egg = Conclusions: The mass of the egg (increased/decreased/remained the same) in the corn syrup. The control egg s mass (increased/decreased/remained the same). hypothesis was that it would (increase/decrease/remain the same), so this data (does/does not) support the hypothesis. Explain. The Evaluation: How could this experiment be improved?