Osmosis and diffusion

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Ian
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Joined: 16 Oct 2006, 10:00
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School: Macarthur Anglican School
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Re: Osmosis and diffusion

Post by Ian »

Rita wrote:Hi All

We did the iodine and starch solution for this prac without measuring side of things. The teacher also asked for sucrose and glucose both 1M. Has anyone used these as well for diffusion prac? Seems a strong concentration....1M sucrose is 34.23%.
Thanks for your thoughts.
Rita
I think sometimes, teachers say "1 molar" when what they mean is just "sort of standard concentration, but not too strong" I once had a teacher ask me for a 1M concentration of Calcium Carbonate!!!! (I stirred that for a long time before twigging that CaCO3 is insoluble! And she wasn't even pranking me!!) :giggle: :crazy:
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Ian
Posts: 573
Joined: 16 Oct 2006, 10:00
Job Title: Lab Assistant
School: Macarthur Anglican School
Suburb: Cobbitty
State/Location: NSW

Re: Osmosis and diffusion

Post by Ian »

melsid wrote:My lot order a saturated sucrose solution, but I've been giving them around 5 - 10% or so and it works just fine.
Saturated Sucrose solution? Is that "Stick jaw" toffee or "Brittle" toffee? Sounds yummy either way! \:D/
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Kathryn
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Re: Osmosis and diffusion

Post by Kathryn »

Good morning. My teacher has always asked for litres of iodine solution to pour straight into the beakers containing the starch dialysis tubing. Of course when I make up the iodine as per the recipe it is far too dark so then have to dilute. Should she actually just be adding a few drops of iodine from our usual 0.1M iodine dropper bottles to water filled beakers?
thanks :)
bigmack
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Re: Osmosis and diffusion

Post by bigmack »

Droppers won't do it .....its just not strong enough .

I give them a small stock solution of Iodine that is 10x strength ( I dilute it down for droppers )

They just carefully add it to the water in the beaker , gas jar what ever , until it is a pale brown colour . ....works everytime
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