To calculate heat, you use the formula Q=mcAt (A is representing delta)
Q is heat in Joules
m is mass in grams
c is specific heat in J/g degrees C
At is change in temperature
Example 1: Calculate the amount of energy in joules required to heat 454 grams of water from 5.4C to 98.6C:
Q=? m=454g At=93.2 Ti=5.4 Tf=98.6 c=4.184
454(4.184)(98.6-5.4)= 1.77x10^5 J OR 177 kJ
Example 2: A 2.6g sample of metal requires 15.6J of energy to change its temperature from 21C to 24C. What's the identity of the metal?
m=2.6g Q=15.6J Ti=21 Tf=34 c=?
15.6=2.6(c)(34-21)
C=.46 J/gC OR Iron
These are great examples! I totally should of worked through these before the test, but I will definitely be re looking at these for the final!
ReplyDeleteI feel like using this equation was my favorite part of this unit because it was fairly easy to understand. Also, I like how you showed your work in your examples. It shows that you know what you are doing!
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