- #1
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Homework Statement
A certain humidifier operates by raising water to the boiling point and then evaporating it.
Every minute 30 g of water at 20◦ C are added to replace the 30 g that are evaporated. The
heat of fusion of water is 333 kJ/kg, the heat of vaporization is 2256 kJ/kg, and the specific
heat is 4190 J/kg · K. How many joules of energy per minute does this humidifier require?
A. 3.0 × 104
B. 8.8 × 104
C. 7.8 × 104
D. 1.1 × 105
E. 2.0 × 104
Homework Equations
Q=mL+mCdeltaT
The Attempt at a Solution
energy per minute = (energy needed to heat water to boiling point) + (energy needed to convert liquid water to gas at the boiling point)
E = (30 g)(4.190 J/g-°C)(100 - 20°C) + (30 g)(2256 J/g)
E = 7.8e4 J but the correct answer is B?