Question

How many joules are needed to heat 20.0 g of Au from 10°C to 50°C? show work

Answer 1

Answer:

297 J

Explanation:

The key to this problem lies with aluminium's specific heat, which as you know tells you how much heat is needed in order to increase the temperature of 1 g of a given substance by 1∘C.

In your case, aluminium is said to have a specific heat of 0.90Jg∘C.

So, what does that tell you?

In order to increase the temperature of 1 g of aluminium by 1∘C, you need to provide it with 0.90 J of heat.

But remember, this is how much you need to provide for every gram of aluminium in order to increase its temperature by 1∘C. So if you wanted to increase the temperature of 10.0 g of aluminium by 1∘C, you'd have to provide it with

1 gram0.90 J+1 gram0.90 J+ ... +1 gram0.90 J10 times=10×0.90 J

However, you don't want to increase the temperature of the sample by 1∘C, you want to increase it by

ΔT=55∘C−22∘C=33∘C

This means that you're going to have to use that much heat for every degree Celsius you want the temperature to change. You can thus say that

1∘C10×0.90 J+1∘C10×0.90 J+ ... +