With schools around the civilization shut down, I recognize that you can be scrambling for activities that have the right to be done through students online. I have taken this standard biology lab task illustrating the ethics of diffusion and osmosis and adjusted it as an digital activity. I did this lab plenty of times through my 10th grade continual bio class at Kelly High college in Chicago, yet it have the right to be used successfully with kids ranging from middle school to AP Bio. Students deserve to read through the lift here and also make their own graphs, analyze these data, and draw conclusions.

You are watching: How to determine the molarity of a potato

I understand you room working harder than ever prior to to teach your students despite the challenges you face. Ns hope you can use this activity or among the rather on this blog. Indict are here if friend would favor to create complimentary access come aramuseum.org for you students because that 90-days. Stay well.

-Aaron Reedy


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Background

Molecules are constantly in activity as a an outcome of a cell\"s save kinetic energy, which causes them come bump into each other and move in random brand-new directions. Diffusion is the activity of molecule from an area of wherein there are plenty of (high concentration) to an area whereby there room fewer (low concentration). Osmosis is the diffusion the water through a semipermeable membrane. That is necessary to remember the a semipermeable membrane permits the solvent (usually water) to pass through, however restricts the activity of a solute (a thing liquified in the solvent). Water will move across a semipermeable membrane native an area of lower solute concentration to an area of greater solute concentration.


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When each side that a membrane has actually equal solute concentration, the equipment is claimed to it is in isotonic and also water molecules will certainly be equally most likely to move in both directions across the membrane. In the case of a hypertonic solution, over there is much more solute outside the cell 보다 inside the cell. Hypertonic solutions cause water molecules to relocate out of the cell and into the an ar of higher solute concentration. Conversely, in hypotonic services there is a greater solute concentration within the cell 보다 outside, and water molecules move right into the cell. At any time possible, water will constantly move from an area of high water concentration/low solute concentration to an area of short water concentration/high solute concentration.


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In this activity, we room going to discover osmosis by looking at a dataset produced with a standard classroom experiment. The experiment supplies pieces that potato that are put in six various solutions of water each through a different solute concentration. The solute is sucrose and the concentrations are measured in systems of molarity. The solutions selection from no solute to a high concentration of solute and also are 0.0 (distilled water), 0.2, 0.4, 0.6, 0.8 and also 1.0 molar sucrose.

Pieces that potato are reduced to similar sizes, weighed, and also then placed in among the 6 solutions overnight. The following day, the potato piece are eliminated from the solutions, blotted dry, and their last masses space recorded.

Each heat in this tidy dataset contains an monitoring for a single potato piece. Each obelisk in the dataset is a variable and the cell in that tower are the worths of that variable. The variables recorded for each potato piece are Lab team Name, Sucrose Concentration (Molarity), Initial mass (g), last Mass (g), and Mass adjust (%).


To check out a video clearly illustrating and also explaining the basic procedure for this lab, watch Paul Andersen’s Bozeman Science video clip walkthrough:


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The activity

1. Click the yellow Make a graph switch to visualize your data. Pick the scatter plot symbol and display Sucrose Concentration (Molar) ~ above the X-axis and also Mass change (%) on the Y-axis. Friend can include descriptive statistics like way and medians by check the box just to the right of the graph.

Observe fads in the data:

2. What room the independent and dependent variables in this experiment?

3. How does change in fixed (%) change with Sucrose Concentration (Molarity)?

4. Which substance moved across the to move membrane in this activity? What is the certain name of the movement in terms of this substance?


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5. Now, adjust the variable referred to as Sucrose Concentration (Molarity) come a Numeric variable v the dropdown food selection right listed below the change name near the optimal of the page. Then include it ago to the graph again by click the present button. Finally, add a regression line of best fit by checking the box just to the right of the graph.

What is your finest estimate for the natural solute concentration inside a potato cell? explain how her data is proof for that estimate.

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6. Which equipment is closestly to gift isotonic through respect come a potato cell? Which services were hypertonic/hypotonic? just how do girlfriend know?

Challenge question:

7. Making use of the principles illustrated with this data, describe why you can’t drink seawater when lost at sea.


For a fast explanation of diffusion and osmosis, we extremely recommend Paul Andersen’s AP Biology laboratory 1: Diffusion and Osmosis video. The explanation the the potato rap starts at 5:36.