1.2 xx 10^5 J of thermal energy are added to a sample of water and its temperature changes from 229 K to 243 K. What is the mass of the water?

1 Answer
Mar 23, 2016

Delta H = mCDeltaT

Rearranging:

m = (Delta H)/(CDeltaT)=(1.2xx10^5)/(4181xx(243-229))=2.1 kg

Explanation:

We use the equation Delta H = mCDeltaT where m is the mass (kg), T is the temperature (K), H is the thermal energy (J) and C is the specific heat (Jkg^-1K^-1). Delta just means 'the change in'.

We know that for water, C=4181 Jkg^-1K^-1. (Sometimes quoted as 4.2 Jg^-1K^-1, but it's better to work in SI units.)