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Thermochemistry please help

Thermochemistry please help!!!!!!!!!!!!!!!!!!

1. Homework Statement

Not sure how to go about this problem.

Calculate the number of grams of propane (C3H8) required to heat all of the water in a 50-gallon hot-water tank from 23.4 degrees C to 65.0 degrees C if the water tank itself has a heat capacity of 23.4J/ degrees C, and it also uses 2.3 kg of copper pipe.

HELP PLEASE!


2. Homework Equations

SH of water 4.184kj/g oC

q= specific heat* mass * change in temp

3. The Attempt at a Solution

Change in temp is 41.6 oC change in H rxn for propane combustion = -2042.804 kj

tried coverting the kg into grams and the 50 gal into grams and plugged in the info for heat lost by tank = heat gained by water (sh*mass*change in t) =-(sh*mass*change in t). I don't know what to use anymore and how to put the problem together because I keep getting ridiculous answers.
 

Answers and Replies

Gokul43201
Staff Emeritus
Science Advisor
Gold Member
6,987
14
Intially, the water, tank and copper pipes are all at the same temperature : 23.4*C.
Finally, they all reach the same temperature: 65.0*C

So first, can you calculate how much heat is required to raise the (water) + (tank) + (pipes) through a temperature difference of 41.6*C?

Remember to be careful with units; Joule is an SI (or MKS) unit, as is kilogram.
 

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