January 11, 2025, 05:05:03 PM
Forum Rules: Read This Before Posting


« previous next »
Pages: [1]   Go Down

Topic: Heat transfer....  (Read 6099 times)

0 Members and 1 Guest are viewing this topic.

hannah

  • Guest
Heat transfer....
« on: April 20, 2006, 07:40:13 PM »
Uhh okay if you have different amounts of a solution and mix them how do you find the resulting temperature?

Specifically, if you have 30 g H2O at 40 degrees C and 100 g H2O at 70 degrees, what's the resulting temp??

Thanks...
hannah
Logged

Offline Qazzian

  • Regular Member
  • ***
  • Posts: 42
  • Mole Snacks: +13/-6
  • Gender: Male
  • Text? We don't need no stinking text!
Re: Heat transfer....
« Reply #1 on: April 20, 2006, 09:40:51 PM »
For that, since it's the same type of liquid (water) in both, just take a weighted average of the temperatures.
Logged
Biochemistry student. Third Year. University of Waterloo. Canada.

Hire Co-Op!

Offline mike

  • Retired Staff
  • Sr. Member
  • *
  • Posts: 1245
  • Mole Snacks: +121/-35
  • Gender: Male
Re: Heat transfer....
« Reply #2 on: April 20, 2006, 10:12:56 PM »
Thermometer ::)
Logged
There is no science without fancy, and no art without facts.

hannah

  • Guest
Re: Heat transfer....
« Reply #3 on: April 20, 2006, 11:13:50 PM »
I sort of thought of that, but what if its two different liquids like water and ethanol if i spelled that right?
Logged

Offline Borek

  • Mr. pH
  • Administrator
  • Deity Member
  • *
  • Posts: 27895
  • Mole Snacks: +1816/-412
  • Gender: Male
  • I am known to be occasionally wrong.
    • Chembuddy
Re: Heat transfer....
« Reply #4 on: April 21, 2006, 02:45:47 AM »
Heat balance.
Logged
ChemBuddy chemical calculators - stoichiometry, pH, concentration, buffer preparation, titrations.info

Offline xiankai

  • Chemist
  • Full Member
  • *
  • Posts: 785
  • Mole Snacks: +77/-37
  • Gender: Male
Re: Heat transfer....
« Reply #5 on: April 21, 2006, 07:07:02 AM »
heat loss by a substance = heat gain by another substance, assuming no heat loss to surroundings and 100% efficiency

the formula for heat is q = m c dT

where m is mass, c is the specific heat capacity and dT is the temperature change
Logged
one learns best by teaching

hannah

  • Guest
Re: Heat transfer....
« Reply #6 on: April 21, 2006, 08:39:14 AM »
Right but how do you do that with two unknowns? it doesn't give me Q or dT...
Logged

Offline Borek

  • Mr. pH
  • Administrator
  • Deity Member
  • *
  • Posts: 27895
  • Mole Snacks: +1816/-412
  • Gender: Male
  • I am known to be occasionally wrong.
    • Chembuddy
Re: Heat transfer....
« Reply #7 on: April 21, 2006, 08:59:43 AM »
Q gained = Q lost, that takes care about first unknown.

Final temperature of both liquids is identical, that takes care of dT.
« Last Edit: April 21, 2006, 09:07:19 AM by Borek »
Logged
ChemBuddy chemical calculators - stoichiometry, pH, concentration, buffer preparation, titrations.info

Offline Donaldson Tan

  • Editor, New Asia Republic
  • Retired Staff
  • Sr. Member
  • *
  • Posts: 3177
  • Mole Snacks: +261/-13
  • Gender: Male
    • New Asia Republic
Re: Heat transfer....
« Reply #8 on: April 21, 2006, 02:58:45 PM »
Although there is 2 unknown (c and Tfinal), c cancels out because both "substances" are actually water and therefore have the same heat capacity.
Logged
"Say you're in a [chemical] plant and there's a snake on the floor. What are you going to do? Call a consultant? Get a meeting together to talk about which color is the snake? Employees should do one thing: walk over there and you step on the friggin� snake." - Jean-Pierre Garnier, CEO of Glaxosmithkline, June 2006
Pages: [1]   Go Up
« previous next »
Sponsored Links