Thermodynamics and Energy Changes (5E) Practice Test

A researcher cools $100\ \text{g}$ of saline (approximate as water, $c=4.18\ \text{J/(g\cdot ^\circ C)}$) from $25^\circ\text{C}$ to $20^\circ\text{C}$ in a calorimeter. The concept is heat exchange with $q=mc\Delta T$. Which sign and magnitude of $q$ for the saline is most consistent?

A researcher runs a reaction in a closed container with a movable piston at constant external pressure. The system expands, doing $150\ \text{J}$ of work on the surroundings (take work done by the system as $w<0$), and absorbs $60\ \text{J}$ of heat from the surroundings ($q>0$). The concept is first law of thermodynamics, $\Delta U=q+w$. Which internal energy change is most consistent?