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Fri 11 Feb, 2005 09:08 pm
Could someone please help me with this..
I have to design an experiment for school to find the density of ice by a Flotation Method.
This is the apparatus that we are given:
* 100ml measuring cylinder containing 100 ml of water of density 1g/cm3 (that's 1 gram per cm cubed.. i didn't know how to write it well with the keyboard)
*250ml beaker containing 100ml of methylated spirit of density 0.8 g/cm3
*Cubes of ice of density approximately 0.9 g/cm3
*Empty measuring cylinder, beam balance and a plastic spoon
"It is difficult to find the density of ice at room temperature with the normal weighing and displacement method because ice melts to form water of a different density"
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I'm not too sure how is supposed to work, the only thing I know is that I think the answer lies in that the densities of the methylated spirit and water are different..
Please any assistance, thoughts, comments would be appreciated..
Thanks very much.
Make Ice Sink
The goal here is to find out where the ice is neutrally bouyant.
You can start weighing your empty flask and recording the weight. Now put the ice and water in the flask. The ice floats of course. Now start adding methylated spirit. This drives the density of the liquid down. The more you add, the more the density drops. When the ice stops floating, the density of the liquid is the same as that of the ice. Take out the ice, and measure the volume and weight of the mixture. Be sure to substract the original weight of the flask. From that you have your density (weight / volume).
If some of the ice melts, that is ok since it just adds to the mixture. Of course, as it melts, it adds water and changes the density, so you probably want to have more water in the flask to begin with so the rate of water addition from the cube is relatively small.
Ice in is ok
On second thought, you don't need to remove the ice.
Wow, this is the second time you've come to my rescue engineer!
Your suggestion worked out very well, thank you so much again!
Glad to help again
Once again, glad to help. It sounds like you are in an interesting class.
One more thought...
Another way to do this without the water is fill the flask half full of the low density liquid, weigh and note the volume. Add the ice cube, let it sink, weigh and note volume again. Delta weight / Delta volume = density.
I appreciate the answers too, engineer.
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