on a day when a man shows no visible perspiration he will still evaporate about 600g of water from his lungs..

Question

on a day when a man shows no visible perspiration he will still evaporate about 600g of water from his lungs.
a.) how many calories of heat are removed by this evaporation?
b.) what is the rate of heat loss in watts due to this process?

Answer 1

the latent heat of vaporization for water is 540 cal/g

a) 600*540
=324 kCal (equivalent to a food Calorie)

b)One calorie is equal to 4.18 Joules
1 watt = 1 joule/second

a day has 24 hours
an hour has 60 min
and a min has 60 seconds

convert the energy to Joules
324000*4.18
=1354320 joules
seconds in a day
=24*60*60
=86400


=1354320/86400
=15.7 W

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