Heat, mass, specific heat capacity, and temperature are related by
`q = mcDelta T`.
The `Delta T` term should be calculated by subtracting the lower temperature from the higher temperature to ensure that `q` is always positive.
If 25.6 g of aluminum absorbs 0.5571 kJ of heat and its temperature rises to 42.6 ºC, what was its original temperature? (The specific heat of aluminum is 0.900 J/gºC.)
We can rewrite `q=mcDelta T` as `q=mc(T_2-T_1)`. Rearranging this gives us
`T_1 = T_2 - q/(mc)`,
and, making sure to convert heat from kilojoules to joules so that it matches the specific heat unit, we can substitute our givens:
`T_1 = 42.6\ "ºC" - (0.5571\ "kJ")/((25.6\ "g")(0.900\ "J/gºC")) = 18.4\ "ºC"`.