A calorimeter begins with 21.0 mL at 11.0 Celius. When a 2.10 g/mol added ( a substance with a molar mass 76.0g/ mol ) is added and dissolved in the reaction

Your question is not complete. Could you re-post it please?

And while you're at it, post also your attempt at solving the problem.

Maybe you'll need to use this formula:

Where Q is the energy involved,
m the volume or mass of water,
c the specific heat capacity of water,
and theta the change in temperature.