Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Temperature change boiling water

  1. Dec 11, 2005 #1
    An iron cylinder is heated to 100.degrees C in boiling water ant then transferred to 145.0 grams of water in a 70.0 gram copper calorimeter at 20.0 degrees C. If the final temperature is 25.2 degrees C find the mass of iron used.

    Would I use mL(Boiling water)+mcT(water)+mcT(coper calorimeter) +mcT (iron)???

    And what would be negative?
     
  2. jcsd
  3. Dec 11, 2005 #2

    Astronuc

    User Avatar
    Staff Emeritus
    Science Advisor

    The iron will lose heat, so its temperature must decrease from 100°C to Tf = 25.2°C.

    The 145 grams of water and the 70 g of copper in the calorimeter will experience a temperature increase from 20°C to Tf = 25.2°C.
     
  4. Dec 11, 2005 #3
    Ok so is that the right equation because it keeps giving me a negative
     
  5. Dec 11, 2005 #4

    Astronuc

    User Avatar
    Staff Emeritus
    Science Advisor

    Try, mc[itex]\Delta{T}[/itex](water)+mc[itex]\Delta{T}[/itex](copper calorimeter) +mc[itex]\Delta{T}[/itex] (iron) = 0.

    The boiling water has nothing to do with the heat transfer. The only significant factor as far as boiling water is concerned is that the iron is heated to 100°C.
     
  6. Dec 11, 2005 #5
    Ok so I've got (.1450)(4.186)(5.2) +(.070)(.85)(5.2) +(m)(.44)(-74.8)Which gives me 8.8194=2.912m and m=.255kg
    So the iron cylinder is going to have more mass than the water and the calorimeter????
     
  7. Dec 11, 2005 #6

    Astronuc

    User Avatar
    Staff Emeritus
    Science Advisor

  8. Dec 11, 2005 #7
    Oops! so (.1450)(4.186)(5.2) +(.070)(.385)(5.2) +(m)(.44)(-74.8) which gives me 3.296384=32.912m which gives the mass to be .100kg this makes more sense thanks!!
     
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook