Question

Solid magnesium has a specific heat of 1.01 J/g°C. How much heat is given off by a 20.0 gram sample of magnesium when it cools from 70.0°C to 50.0°C?

Answer 1

I got `-404 J` of heat being given off.

Explanation:

Let's get started by using the specific heat capacity equation:

Based on what you've given me, we have the mass of the sample (m), the specific heat (c), and the change in temperature `DeltaT`.

I should also add that "m" isn't limited to just water, it can be the mass of almost any substance. Also, `DeltaT` is `-20^oC` because the change in temperature is always final temperature- initial temperature
(`50^oC - 70^oC`).

All of the variables have good units, so we just have to multiply all of the given values together to obtain Q (energy transferred).

`Q = 20.0cancelgxx(1.01J)/(cancelgxx^ocancelC)xx-20^ocancelC`

`Q = -404 J`