1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    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!

Homework Help: 10 gal of Jell-O

  1. Sep 22, 2005 #1
    As I am actually performing this, it occurred to me I'm a bit rusty and cannot define the formula to calculate the following process. Anyone who can solve this and show a proof, your help would be appreciated. NO, I'm not a student looking for someone to do my work, I've been out of school for 7 years..... which is why I'm rusty.

    10 US gal of a solution is made using 5 gal of boiling water, added to 5 gal of a solution (which is 99% water).
    These 10 gal are then placed in an empty locker freezer, which is approx 10 cubic ft, and has an ambient temp of -10 degrees(F).

    My question is: how long should it take to cool the solution to 35 degrees(F)?
    I have not been able to figure out cold output of the freezer, so answer would have to use a variable to define the strength of the freezer's output in the formula for "t".

    Thanks in advance.
  2. jcsd
  3. Sep 22, 2005 #2


    User Avatar
    Science Advisor

    Without going into a huge heat transfer analysis, I'd estimate it using Newton's law of cooling:

    [tex]q = m C_p \Delta T[/tex]

    The only thing you'll have to do is to use a bit of chemistry to calculate the specific heat of the mixture. Once you know that, you need the capacity of the freezer in some units along the lines of btu/min to calculate the time necessary.
    Last edited: Sep 22, 2005
  4. Feb 10, 2010 #3

    I am a student doing a science project where I need to know the specific heat of Jell-O. I googled "specific heat of Jell-O" and this thread came up. Sorry to be a bit random, but do you know the specific heat of Jell-O? It would help me immensely, as I have not had enough schooling yet to know how to calculate this.

    Thank you,

    A middle school student
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook