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Practical: Observing osmosis in potatoes
Engage
Engage
Read this recipe for baked potato chips
Start by preheating your oven to 400 degrees. Slice your potatoes into sticks that are about 1/3” thick. Place the potatoes into a bowl of cold water, along with a couple of tablespoons of salt. Allow the fries to soak in the salted water for about 15 minutes.
When you’re ready to cook the potatoes, drain them and pat dry.
Place your fries into a bowl and pour the olive oil over the top. Toss the fries with your hands to ensure that they are all coated with oil. Then transfer the oiled fries to a couple of baking sheets. (I used my oven mats on my baking sheets, because they make clean-up so easy!)
Spread the fries into a single layer on each baking sheet. Then sprinkle the dried herbs evenly over the potatoes, followed by the cheese and parsley.
Bake until the potatoes are golden brown, about 45 to 50 minutes. Rotating the pans after 30 minutes to ensure they bake evenly.
Removed the finished fries from the sheets and sprinkle with salt and pepper to taste. Serve hot, along with your favorite dipping sauce. Yum!
Question: Why does the author suggest soaking the potato slices in salted water before cooking them?
Explore and Explain
AIM
To investigate the effect of salt water concentration on osmosis in potato slices
HYPOTHESIS
Make a prediction based on what you have learned thus far as to what will happen to the size of the gummy bear in each of the two different solutions.
MATERIALS (per group)
Distilled water
Measuring cup with milliliters (mL)
Table salt
Weight scale with gram measurements
Three beakers
Spoon
Potato slices (x3)
Knife
Ruler
METHOD
1.) Prepare three different saltwater solutions. Create labels for the three cups: "0 grams," (as a control), "2 grams" and "4 grams."
2.) To each of the cups add 100 mL of distilled water.
3.) Weigh out 2 grams of table salt, and add it to the cup that says "2 grams." Then weigh out 4 grams of table salt, and add it to the cup labeled "4 grams." Use a spoon to mix the solutions until all the salt is dissolved.
4.) Prepare three potato slices in a rectangular prism shape, approximately 5 x 2 x 2 cm in dimensions. Ensure they are as similar in size and shape as possible.
5.) Record initial measurements for each potato slice - dimensions (length, width, height), and weight
6.) Place one of each of the potato slices into each of the beakers
7.) Allow the potato slices to sit in solution for 30 minutes, then return to re-record your observations. Record your initial and final results in the table below.
RESULTS
Use the following table to record your observations
DISCUSSION
What happened? Did the potato slices shrink or expand? Did they lose weight or gain weight? How did the concentration of salt in solution relate to these changes?
Draw a diagram of the potato slice in the three different solutions to show the net movement of water. Identify which solution is hypotonic and which is hypertonic (with respect to the potato slice)
CONCLUSION
Write a suitable conclusion that links back to your aim and hypothesis
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