majoji Posted November 7, 2011 Report Share Posted November 7, 2011 We're doing our first lab this Thursday, and out teacher told us to start thinking and planning the experiment. I have planned to use a bag made from dialysis tubing containing a solution of sodium chloride. I will lower the bag into distilled water and see if the volume increases. However, my teacher keeps asking me if this is such a good idea and if I could do it in any other way. What do you think? Do I have a good plan? What is missing? What should I do? Reply Link to post Share on other sites More sharing options...
dessskris Posted November 7, 2011 Report Share Posted November 7, 2011 (edited) why not design a simpler experiment?things to keep in mind:- you need to have an independent variable- you need to have a dependent variable- your controlled variables must be controllable or at least monitorable- the apparatus used need to be common/normal lab apparatus- the experiment needs to be feasiblethink about simpler experiments, like putting a piece of potato in sugar solutions of different concentrations and then measure the change in mass, perhaps?EDIT:just want to add, you need to have at least 5 values for your independent variable. in my example it would be the concentration of the sugar solution, so I need to have at least 5 solutions with different concentrations. and of course one must be a control (with 0 concentration i.e., use pure distilled water) Edited November 7, 2011 by Desy Glau Reply Link to post Share on other sites More sharing options...
Drake Glau Posted November 7, 2011 Report Share Posted November 7, 2011 We're doing our first lab this Thursday, and out teacher told us to start thinking and planning the experiment. I have planned to use a bag made from dialysis tubing containing a solution of sodium chloride. I will lower the bag into distilled water and see if the volume increases. However, my teacher keeps asking me if this is such a good idea and if I could do it in any other way. What do you think? Do I have a good plan? What is missing? What should I do? See if you can use a starch solution instead of NaCl. NaCl might be small enough to pass through the tubing so the osmosis would be more than osmosis. You can then just change the concentration of the starch solution by diluting the sample in equal increments and then theoretically the mass increase in your bag should decrease as the concentration of starch in the bag decreases. Seems like a simple lab already to me. Fill bags, mass bags, place bags in water for x minutes, mass bags, repeat. We actually did this in your HL bio class also, first lab we did 1 Reply Link to post Share on other sites More sharing options...
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