# The temperature of a sample of water changes from 10°C to 20°C when the water absorbs 420 joules of heat. What is the mass of the sample?

Mar 2, 2016

$10.03$ grams

#### Explanation:

The problem can be solved using the formula:

$Q = m C p \Delta T$

where:

$Q = h e a t$
$m = m a s s$
$C p = s p . h e a t$
$\Delta T = t e m p e r a t u r e$ change $\left({T}_{2} - {T}_{1}\right)$

Some data are provided in the problem like
$Q = 420$ Joules
${T}_{2} = {20}^{o} C$
${T}_{1} = {10}^{o} C$
and the [specific heat](http://socratic.org/chemistry/thermochemistry/specific-heat) of water is known to be 4.186 (J)/(g.^oC). (http://www.calculator.org/property.aspx?name=specific%20heat%20capacity)

All you have to do is to rearrange the original formula to isolate $m$ and to derive the new formula which is;

$m = \frac{Q}{C p \Delta T}$, plug in values and make sure to cancel out units.
until you have the desired unit.