Why does sugar water evaporate faster than salt water?

Answer 1

Dissolving something in water which does not evaporate easily will make the mixed solution less likely to evaporate than pure water. The more stuff you add to it, the less likely it will evaporate. Adding salt to water makes ions in solution and these ions reduce the vapor pressure of the solution compared to pure water. The lower the vapor pressure of a liquid or solution, the slower it will evaporate. This effect is also related to boiling point elevation and freezing point depression. The following is taken from the site listed to the left of this answer, but that page has a lot of additional information, and this is the most important part. This is the real reason the vapor pressure of salt solutions are decreased: "The reason dissolved solutes (such as salt) increase boiling point is that the solute must come out of solution in order for the water to boil. This costs entropy (the entropy of solution). Boiling is entropically driven, hence the reduction in the net entropy gain of boiling results in a higher temperature needed for the reaction to go. To put it without jargon: for a little packet of water with dissolved salt to turn to steam the salt atoms must, in the course of their random zooming about, ALL simultaneously leave the packet. This is not a likely event. It becomes more likely as the temperature (i.e. the average speed of zooming about) becomes higher, though, and at a certain temperature above the ordinary boiling point it becomes sufficiently likely to allow boiling in spite of the handicap. You can also see that the effect will naturally increase with the concentration of dissolved solutes (i.e. the number of salt atoms per packet that must simultaneously leave)."

Answer 2

Anything that you add to water like sugar or salt will lower its freezing temperature. This is called freezing point depression, where dissolved molecules interfere with the formation of ice crystals, lowering the freezing point of the solution. Salt is used on roadways to melt ice by prevent it from re-freezing at the same temperature.

Answer 3

The evaporation rate of water is independent on the type of solute.
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New answer:

If you used the same amount of each, such as 1 cup of sugar water, and 1 cup of plain water, then the sugar water will evaporate to dryness faster.
This is because you are not starting with the same amount of water.

If you want to test which will be faster, start with the same amount of water, such as 1 cup in each of two, separate, same size, bowls.
Add 1 cup of sugar to one of the bowls and stir carefully until the sugar dissolves.
Check the temperature of each bowl now. Is one warmer or colder than the other?
Place both bowls in a quiet, open area, safe from being spilled. Allow them to evaporate.
Check them daily, record your results and observations.
Report what happened here to supply a scientific answer to your own question.

Answer 4

* My prediction was the salt and water will evaporate first because it has more chemicals than plain water. * My answerWhen salt or sugar water evaporate they leave higher concetrations of salt and sugar at the evaporating surface which mean fewer water molecules can present themselves to the surface to effect evaporation. Look up azinotropes inchemestry text. whom ever asked this quetion this will be a good science fair project this is my scince project Also, because when salt is put into water, they can also act like magnets. Attaching to opposite particles. The salt molecules also push down the water molecules so the water molecules have to get enough power to evaporate. Which makes plain water evaporate faster. Salt=sugar and salt :D

Answer 5

Water evaporates at the same rate for a given temperature, regardless of the dissolved materials. However, any salt in water will LOWER the freezing point and RAISE the boiling point by interfering with the change in state of water molecules.

Answer 6

Because sugar particles are tiny and dissolve! To where if you think of salt water, the particles are bigger and doesn't dissolve better. That's why oceans are salt water and if you get some in your mouth, its all salty because salt doesn't neccessarly dissolve!

Answer 7

Water evaporates at the same rate as water...

Answer 8

It does.