# How do you determine the mass of a water sample that is heated from an initial temperature of 25 deg C to a final temperature of 100 deg C following the addition of 1200 J of heat energy?

Dec 14, 2016

Here's how I would do it.

#### Explanation:

The formula for the amount of heat absorbed by a substance is

color(blue)(bar(ul(|color(white)(a/a)q = mcΔTcolor(white)(a/a)|)))" "

where

$q$ is the quantity of heat
$m$ is the mass of the substance
$c$ is the specific heat capacity of the material
ΔT is the temperature change

You can rearrange the formula to calculate the mass:

m = q/(cΔT)

$q = \text{1200 J}$
$c = \text{4.184 J·°C"^"-1""g"^"-1}$ (the specific heat capacity of water)
ΔT = T_f - T_i = "100 °C - 25 °C" = "75 °C"
m = (1200 color(red)(cancel(color(black)("J"))))/(4.184 color(red)(cancel(color(black)("J·°C"^"-1")))"g"^"-1" × 75 color(red)(cancel(color(black)("°C")))) = "3.8 g"