Diffusion And Osmosis Experiments Flashcards
Potato cylinders experiment
Used to explain osmosis. You cut up a potato into identical cylinders and get some beakers with different sugar solutions in them. One should be pure water, another should be a very concentrated sugar solution. Then you have other beakers with concentrations in between. You measure the length of the cylinders then leave a few cylinders in each beaker for half an hour of so then take them out and measure them again. If the cylinders have drawn in water through osmosis they’ll be a bit longer. If water has been drawn out they’ll have shrunk a bit.
The dependant variable is the chip length and the independent variable is the concentration of the sugar solution.
Visking tubing experiment
Tie a piece of wire around one end of some visking tubing and put a glass tube in the other end. Then pour some sugar solution (hypertonic) down the glass tube into the visking tubing. Put he visking tubing in a beaker of pure water (hypotonic) measure where the sugar solution comes up to on the glass tube. Leave the tubing overnight hen measure where the liquid is in the glass tube. Water should be drawn into the visking tubing by osmosis and this will force the liquid up the glass tube.
Agar jelly experiment
Used to investigate diffusion. Phenolphthalein is a PH indicator- it’s pink in alkaline solutions and colourless in acidic solutions.
1) first, make up some agar jelly with phenolphthalein and dilute sodium hydroxide. This will make the jelly pink.
2) then fill a beaker with some dilute hydrochloric acid. Using a scalpel cut out a few cubes from the jelly and put them in the beaker of acid
3) if you leave the cubes for a while they’ll eventually turn colourless as the acid diffuses into the agar jelly and neutralises the sodium hydroxide.
