How can you measure the heat capacity of a calorimeter?

Simple Calorimetry. A piece of solid aluminum at 15.0°C is immersed in 12.3 g of nitrogen gas which is initially at 51.1°C and the system is allowed to equilibrate. Given that the specific heat of solid aluminum is 0.908 J/K/g and the specific heat of nitrogen gas is 1.0 J/K/g, what is the mass of the piece of solid aluminum if the final temperature is 34.7°C?

From a molecular viewpoint, where does the energy absorbed in an endothermic chemical reaction go? Why does the reaction mixture undergo a decrease in temperature even though energy is absorbed?

For an exothermic reaction, how is the measured temperature change affected if some of the heat produced transfers to the calorimeter? How will the determination of the specific heat of the metal be affected if the thermometer used to record the temperature of the water bath reads too low?