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Chemistry Forums for Students => Physical Chemistry Forum => Topic started by: jacko on June 15, 2005, 07:41:18 PM

Title: chemical heat pack
Post by: jacko on June 15, 2005, 07:41:18 PM

hey,
ok so here's my question

1. the specific heat of solid iron is 0.444J/Cg. A heat pack with 4 moles (223g) of Fe gives off the same amount of heat (delta H = -1650kJ) as a piece of solid iron of the same weight cooling from x degrees celcius to 25 degrees celcius

just wondering what the formula i mite need to use is or is there even one??

thanks

Title: Re:chemical heat pack
Post by: Beetle on June 15, 2005, 09:02:18 PM

It took me a while to do this one the other day but what u do is

delta H is the amount of heat the heatpack produces so the piece of iron has to produce the same amount of heat

u can use Q=m.s.delta T on the piece of iron where
Q = delta H
m =223g
and Tf = 25 (remember to change it to Kelvin)

Should be pretty easy from there