It takes an electric tea kettle with 20 degree celsius water 5 min to reach boiling, how long will it take for?
all of the water to boil away, assuming the same rate of heat addition?
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One Response to “It takes an electric tea kettle with 20 degree celsius water 5 min to reach boiling, how long will it take for?”
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specific heat of water is 4.186 kJ/kgC
heat of vaporization of water is 2256 kJ/kg
amount of energy needed to heat M kg of water from 20 to 100ºC is:
E = 4.186 kJ/kgC x 80 x M
amount of energy needed to boil M kg of water at 100ºC is:
E = 2256 kJ/kg x M
ratio of the two is
(2256 kJ/kgC x M) / (4.186 kJ/kgC x 80 x M) = 6.74
so it will take 5*6.74 = 33.7 minutes
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