Anyone remember the ethanol question?
When you add 50 cm3 of ethanol to 50cm3 of water, the total volume of the mixture is 97cm3. Ans: Ethanol molecules fit into the gaps of water molecules
Why does the ethanol molecules fit into the gaps of water molecules. Hell, I didn't know this was in my syllabus.
I read somewhere that ethanol pulls water molecules closer together, because of the fact water molecules are polar. Is that true?
Thanks for helping :D
Originally posted by Garrick_3658:Anyone remember the ethanol question?
When you add 50 cm3 of ethanol to 50cm3 of water, the total volume of the mixture is 97cm3. Ans: Ethanol molecules fit into the gaps of water molecules
Why does the ethanol molecules fit into the gaps of water molecules. Hell, I didn't know this was in my syllabus.
I read somewhere that ethanol pulls water molecules closer together, because of the fact water molecules are polar. Is that true?
Thanks for helping :D
Regarding ethanol "fitting into gaps between" water molecules, that's only an approximate description for the actual process, which is much more complex that can be handled at 'O' levels.
To simplify it - in the liquid state, particles can slide over each other freely (unlike solid state), and hence the ethanol particles can "fit into gaps between" water molecules. This would not be possible in the solid state.
Ethanol is slightly polar (as you increase no. of C atoms, polarity of alcohols decrease), just polar enough to dissolve in water. Enough hydrogen bonding occurs between ethanol and water molecules, that they are miscible (ie. can dissolve into each other).
Hence this "fitting into gaps between" would also not be possible if the alcohol was non-polar (eg. pentanol) and could not dissolve in ("fit into gaps between") water. The volumes would be more significantly conserved (eg. 99cm3) than is the case with a polar alcohol that can dissolve ("fit into gaps between").
Finally, don't worry too much. This is an MCQ qn. It's usually obvious which of the 4 options is the best answer (even if two options may be arguably correct, only one will still answer the question best).
So it's something about states of matter.
Ok thanks.