Question

A sample of solid iodine is heated with an electrical coil. If 90.8 Joules of energy are added to a 11.5 gram sample and the final temperature is 39.4oC, what is the initial temperature of the iodine ?

Answer 1

Recall that the the formula for heat here is
\[q=mc \Delta TC\]
q=joules or energy
m=mass
c=specific heat
tc=temperature change

So..you plug all that in( the stuff given in question)
specific heat of solid iodine=0.427<<according to google

90.8=(11.5)(0.427)(39.4-x)<<as you are heating here, so the initial temperature must be less than 39.4

now you just solve for x..

90.8=4.9105(39.4-x)

distribute like it's algebra

90.8=193.4737-4.9105x

-102.6737=-4.9105x

x=20.91 (rounded)