1. PF Contest - Win "Conquering the Physics GRE" book! Click Here to Enter
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Thermodynamics/ Humdifier

  1. Nov 4, 2016 #1
    1. The problem statement, all variables and given/known data

    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
    2. Relevant equations

    3. 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?????
  2. jcsd
  3. Nov 4, 2016 #2


    User Avatar

    Staff: Mentor

    I get the same answer as you.
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted

Similar Threads - Thermodynamics Humdifier Date
Deriving Fermi-Dirac Distribution misunderstanding Wednesday at 11:10 AM
Ideal gas thermodynamics Mar 6, 2018
Simple thermodynamics problem Mar 3, 2018
Work done in a thermodynamic process Feb 10, 2018