Question

why would isoprophyl alcohol evaporate in your hand even though your hand is lower than the normal boiling point of the alcohol?

Answer 1

Evaporation can take place at any temperature as some energy is transferred to high energy molecules which then turns into gas.

Answer 2

i dont think that explains why alcohol evaporates....does it?

Answer 3

May i explain?

Answer 4

can i take the example of acetone?

Answer 5

why it does not explain it?

Answer 6

Suppose acetone is put on our hand .. it will evaporate and make our palm feel cool

@lgbasallote that is somewhat like your question. right?

Answer 7

When acetone is put on the palm ..

It absorbs energy from our palm ... as latent heat of fusion ..

By gaining .. the energy from the palm it evaporates and since :

EVAPORATION CAUSES COOLING ...............

Hence we feel cool since the heat gets absorbed .. from our palm

Answer 8

does that make sense to you @lgbasallote ?

Answer 9

...no...

Answer 10

where r u having prob?

Answer 11

i have no idea what you're talking about

Answer 12

im not really "chemistry-inclined" so i'd apprecciate it if you avoid using v=many chem words

Answer 13

Ok you mean like : latent heat of fusion?

Answer 14

yes...and this energy mumbo jumbo

Answer 15

I am simply talking about the question that :

the acetone ( example ) absorbs energy from our palm and uses that energy for evaporation

Since : evaporation causes cooling

hence when acetone gets evaporated from our palm , we feel cool :)

Answer 16

evaporation causes cooling?

Answer 17

Basically latent heat of fusion can be defined like this:

this is the energy required to convert 1 kg of solid to 1 kg of liquid at the boiling point and at 1 atmospheric pressure

In other words :

energy required by a solid substance to convert into liquid state is known as latent heat of fusion


FUSION can also be said as : melting

got it now @lgbasallote ?

Answer 18

ok you just made it even MORE complicated =_=

Answer 19

Yes @lgbasallote

evaporation is the process in which liquid state convert into gaseous one

example : water --> water vapour

Since in evaporation : energy if absorbed from the atmosphere .. hence it causes cooling

Answer 20

@lgbasallote .where r u feeling it as complicated ?

Answer 21

why do you keep tagging me o.O lol

Answer 22

and everything

Answer 23

1) i dont get why evaporation causes cooling
2) i dont get how that relates to acetone's evaporation
3) i dont know if acetone and alcohol are the same
4) i dont get this energy absorption mumbo jumbo
5) i do not understand what you call "latent fusion thingy"

Answer 24

i need to go off for a while now

Answer 25

You may prefer to this link for explanation of this topic with pictures : : : http://www.ncert.nic.in/NCERTS/textbook/textbook.htm?iesc1=1-14

Answer 26

nahh..i never prefer links

Answer 27

then sorry ..

Answer 28

@mathslover latent heat of fusion refers to solids, the proper term in this example is latent heat of vaporization

Answer 29

@Igbasallote the key idea is to realize that a sample of matter, in this case alcohol, contains many molecules all at different energies (each molecule moves at a different speed, slamming into the others). The average energy (speed) of the molecules in the sample is what we call its temperature. Now, a very small number of these molecules will have just enough energy to "escape" the bulk sample in your hand, flying off into the air, even though the vast majority of them will not. As these fast moving molecules fly off, they carry the energy they had away with them, so the bulk sample in your hand will now have a lower average energy than it did before. Since the alcohol is in thermal contact with your hand, and your hand and the alcohol are now at different temperatures (your hand has higher temperature than the alcohol) heat must flow from your hand into the alcohol until thermal equilibrium is re-established. Since your hand loses some heat energy, it is cooled off. The process, though relatively slow, continues, and more and more alcohol evaporates. Eventual all the alcohol has evaporated, even though the temperature at which this occurs is less than the boiling point :)

Answer 30

so @eseidl does it happen to all liquids? not just alcohol?

Answer 31

@Igbasallote It happens to all liquids, yes, though the rate of evaporation and intensity of the cooling effect on your hand differ from substance to substance.

Answer 32

so it's possible to evaporate water from my hand too??

Answer 33

this chemistry thing is confusing is screwed up @_@ lol

Answer 34

yes. It doesn't need to be in your hand either. Any glass of water sitting on a table at room temperature long enough will evaporate to dryness. It will take a lot longer than with alcohol though.

Answer 35

lol, yeah

Answer 36

thanks for the help. i wonder how you remember these and you dont get confused =))

Answer 37

Chemistry was my major in University (and I'm a nerd) lol