# 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?

Jun 28, 2016

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 $\Delta T$.

I should also add that "m" isn't limited to just water, it can be the mass of almost any substance. Also, $\Delta T$ is $- {20}^{o} C$ because the change in temperature is always final temperature- initial temperature
(${50}^{o} C - {70}^{o} C$).

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

$Q = 20.0 \cancel{g} \times \frac{1.01 J}{\cancel{g} {\times}^{o} \cancel{C}} \times - {20}^{o} \cancel{C}$

$Q = - 404 J$