GC - Question: Heat lost, heat gained ???

[ckmonster]

This is from Destroyer...

An Unknown metal of 50 grams is initially at 100 ˚C and dropped into a beaker of 200 grams of water at 30 ˚C. The final temperature of the system is 40 C. Find the specific heat of the metal if the heat of water is 4.2 J/g C.

I get that we have to set the equations equal to each other, but i dont get how to properly set the temperatures

m(metal)*c*∆T = m(water)*c(water)∆T

so... (this is the set up given in the solutions)

(50) c (100 - 30) = (200) (4.2) (40-30)


Can someone shed some light PLEASEEEEE???

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[ckmonster]

no body?

 

[nze82]

This is from Destroyer...

An Unknown metal of 50 grams is initially at 100 ˚C and dropped into a beaker of 200 grams of water at 30 ˚C. The final temperature of the system is 40 C. Find the specific heat of the metal if the heat of water is 4.2 J/g C.

I get that we have to set the equations equal to each other, but i dont get how to properly set the temperatures

m(metal)*c*∆T = m(water)*c(water)∆T

so... (this is the set up given in the solutions)

(50) c (100 - 30) = (200) (4.2) (40-30)


Can someone shed some light PLEASEEEEE???

That's because you're not using the correct signs.
The metal loses heat, so the sign must be negative.
Water gains heat, so the sign must be positive.

-Qm = Qw

Now do the math! You should be able to come up with the correct answer.