What dries first?

[wahoo84]

2 towels are soaked in waters of different temperature and then left to dry on a table top in a room of 20C or so.

Would the towel soaked in water of 17C dry first or the towel soaked in water of 80C dry first???

Basically, would a cold towel or a hot towel dry faster??

[noboundaries-au]

I would imagine the hot towel would as the molecules are already somewhat excited.

[Gunna]

Originally Posted by noboundaries-au

I would imagine the hot towel would as the molecules are already somewhat excited.

But the rate at which the towel cools would make no difference I think the towl @ 17c would dry quicker as it would reach ambient temp quicker and begin drying.

It also depend on wind flow etc as well

[Antilochos]

I'm gonna ask a stupid question here: Why do towels dry when left out in the air again?

Is it simply water molecules leaving the towel, as they would if the water were in a glass, like vapor pressures and such? If so, surely the hotter towel would dry quicker, as the higher temperature would provide more energy for the water molecules to leave the towel as a gas. When I'm imagining withdrawing the hot towel from the water, there'd be steam coming off it. Am I on the right track here?

Gotta stop napping through chemistry >.>

[Sureshot]

The towel soaked with 80 degree water will dry first, as it will lose more water mass initially due to the water escaping as steam.

Once you have lost that initial mass, then both towels should lose water at the same rate, since all other variables such as the size of the towel, humidity and air temperature.

So the hotter towel will dry faster.

Give it a try and let us know your results.

[Tragic_Calais]

Hot towel will dry quicker for the exact reason noboundaries stated

Originally Posted by wiki

Evaporation is one of the two forms of vaporization. It is the process whereby atoms or molecules in a liquid state (or solid state if the substance sublimes) gain sufficient energy to enter the gaseous state. It is the opposite process of condensation.

Evaporation is exclusively a surface phenomena and should not be confused with boiling.

The thermal motion of a molecule of liquid must be sufficient to overcome the surface tension to evaporate, that is, its kinetic energy must exceed the work function of cohesion at the surface. Evaporation therefore, proceeds more quickly at higher temperature, at higher flow rates between the gaseous and liquid phase and in liquids with lower surface tension (i.e. higher vapor pressure). Since only a small proportion of the molecules are located near the surface and are moving in the proper direction to escape at any given instant, the rate of evaporation is limited. Also, as the faster-moving molecules escape, the remaining molecules have lower average kinetic energy, and the temperature of the liquid thus decreases. This phenomenon is also called evaporative cooling. This is why evaporating sweat cools the human body.

[wahoo84]

Interesting... I'm too lazy to conduct the experiment... but the factors I have to think about are these...

Say the towel wasn't 80C, more like 50C and not really too "hot"...

- would the hot towel cool down?
- the majority of water molecules are trapped inside the towel
- there is no wind
- equal amounts of water are absorbed by the 2 towels...

hmmmmmmmm

[noboundaries-au]

Originally Posted by Gunna

But the rate at which the towel cools would make no difference I think the towl @ 17c would dry quicker as it would reach ambient temp quicker and begin drying.

It also depend on wind flow etc as well

I didnt mean anything to do with cooling rate.

Tragic has hit the nail on the head

[Tragic_Calais]

Originally Posted by wahoo84

Interesting... I'm too lazy to conduct the experiment... but the factors I have to think about are these...

Say the towel wasn't 80C, more like 50C and not really too "hot"...

- would the hot towel cool down?
- the majority of water molecules are trapped inside the towel
- there is no wind
- equal amounts of water are absorbed by the 2 towels...

hmmmmmmmm

Hotter towel will still dry quicker because the additional heat will allow the water molecules at the surface to phase change quicker. There is not going to be allot of difference because as the surface molecules change they will cool the rest of the water until equilibrium is met. From this point on they will cool equally as long as both still have the same surface area

[Tragic_Calais]

Originally Posted by noboundaries-au

Tragic has hit the nail on the head

Me? Credit where credit is due, you posted the correct answer then I just used wiki to show why you were right

[noboundaries-au]

Originally Posted by Tragic_Calais

Me? Credit where credit is due, you posted the correct answer then I just used wiki to show why you were right

Hehe, yeah i was using your post to show exactly what i meant, rather than my one line response

[Gunna]

but the rate at which the towel cools would be fairly high, i mean the towel wouldn't stay hot for very longs. hence the water still in the towel will be cold.

It like using a face washer in the shower, it is as hot as the water you are using, ring it out, hang it up and come back in a few hours and its cold and wet.

Now wash one in the washing machine and hang it on a clothes horse, dries in a couple of hours, and i realise that the machine has spin cycle etc. I know the spin cycle helps but i think it all comes down to the environment the towel is dried in,

[jkmatt]

Originally Posted by Gunna

but the rate at which the towel cools would be fairly high, i mean the towel wouldn't stay hot for very longs. hence the water still in the towel will be cold.

It like using a face washer in the shower, it is as hot as the water you are using, ring it out, hang it up and come back in a few hours and its cold and wet.

Now wash one in the washing machine and hang it on a clothes horse, dries in a couple of hours, and i realise that the machine has spin cycle etc. I know the spin cycle helps but i think it all comes down to the environment the towel is dried in,

And in this case the environment is a controlled varible. The ONLY difference between the two is the temp of the water, everything else extacly the same.

[DVD]

Sounds like someone should conduct some experiments!

[PLooB]

Isn't evaporation a cooling process and hence the cooler towel will dry quicker?