Physical Science

[sglewis92]

How much heat must be removed when 25 grams of steam at 100°C Is condensed to form liquid water at 100°C?

[factor-fiction]

Did you mean to use the figure of 100°C twice?

[sglewis92]

yes i did

[factor-fiction]

http://cnx.org/content/m42225/latest/
See if you can work it out from a resource such as this if you've left your notes/text books at college

[jim360]

It's a latent heat problem, if I remember correctly.

Formula is then:

Heat energy removed = Latent heat times mass.

[sglewis92]

what is the latent heat?

[jim360]

Latent heat is the energy required to change the state of matter. It depends on what you're using, and also what you are changing state from and to, so that Latent heat of melting is different usually from latent heat of evaporation. Units are Joules per kilogram. Note that there is no temperature dependence so in an ideal experiment all the energy is going into changing the state and not changing the temperature at all. SO you might start with water at 100 degrees Celsius and finish with gas at 100 degrees -- that process took energy.

Examples: if the latent heart of vaporisation of water is 2260 kiloJoules per kilogram then you need 2260*5 = 11300 kiloJoules to completely evaporate 5 kilograms of water.

[vascop]

It's the heat that needs to be removed to change unit mass of steam at 100 degrees centigrade to water at 100 degrees centigrade

[New Judge]

When you asked "what is the latent heat", sglewis, I hope you were seeking the actual figure kindly provided by jim360 and not looking for a definition or explanation of latent heat.

If you were looking for the figure it is easily available from many sources online. If you were looking for an explanation (which can also be found online) there's not much point in simply doing the arithmetic unless you understand the principle involved. It is not very helpful for your teacher/tutor to ask you to do these things if you don't first understand the principles.