Latent heat of steam


by Salerk
Tags: heat, latent, steam
Salerk
Salerk is offline
#1
Feb22-08, 02:54 PM
P: 9
1. The problem statement, all variables and given/known data
Ive been tasked with working out the Latent heat of steam
the following are all my results and values used.

Mass of the calorimeter and stirrer: 0.068Kg
Thermal Capacity of the Calorimeter and Stirrer : 25.772 JK-1
Mass of water and Calorimeter and stirrer: 0.145Kg
Mass of water = 0.077
Thermal capacity of water: 323.4
Thermal capacity of calorimeter and water: 349.172
Starting Temperature: 19.5 Degrees C
Ending temperature 56 Degrees C
Mass of calorimeter & water after passing steam 0.151Kg
Mass of the condensed steam 0.006Kg
Heat gained by the water: 12744.778
Latent heat capacity of steam: 11635.978 Jkg



2. Relevant equations
The equations i had to use are
Thermal Cap of Calorimeter and stirrer = weight x 379 (I cant read my tutors hand wrighting, but i think thats the thermal capacity of copper or along them lines, just know the value 379 to be correct, least I hope it to be)

The Thermal Capacity of water I have as (Total weight - Weight before water added) * 4200

For heat gained by water we where given the equation:
(Thermal Capacity of Water + Thermal Capacity of the Calorimeter) * temprature rise (((From now on referd to as Ct)))

The final equation (and the one I think might be wrong) is this for the calculation of the Latent heat capacity of steam
Ct(T2-T1) - Ms Cw ( 100-T2) / Ms

Ct ((see above))
T2 56 Deg C
T1 19.5 Deg C
Ms = Mass of condenced steam (0.006 kg)
and Cw Ive got down as 4186, I think this is ment to stand for the Thermal Capacity of Water, esp if Ct stands for the CT of water + Calorimeter. If im right then it should be 318.136 not 4186

3. The attempt at a solution

Well most of it ive done above. but i make the answer to be
343.9(56-19.5)-0.006*4186(100-56) / 0.006

geting me the answer of 11275.

Ive been told that its ment to be 2256000 by my tutor but another said it should be 2256. There are a few 000 missing between the, but neather knew the units (yea, I know) so i looked around and I foud that its being said to be 2260J per Gram

This is where im stuck.

Ive just got no idear if ive done this wrong, if ive been told wrong values, so trying to deside if the result ive got is right or wrong is sending me crazy

If anyone can clear this up for me that would be fantastic.

and the final question would be. whats the equation to work out Molar latent heat capacity of steam.?

Thanks very much

Ritchie
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