$4.0 \, L$ of an ideal gas is allowed to expand isothermally into vacuum until the total volume is $20 \, L$. The amount of heat absorbed in this expansion is $..... \, L \, atm$.

Calculate the change in internal energy of the system if work done by the system is $18 \ J$ and absorbs heat $50 \ J$ in a particular reaction. (in $J$)

For the reaction $FeCO_{3(s)} \to FeO_{(s)} + CO_{2(g)}$,$\Delta H = 82.8 \ kJ$ at $25 \ ^oC$. What is $\Delta U$ at $25 \ ^oC$ in $kJ$?

Which of the following processes exhibits an increase in internal energy?

Calculate the quantity of heat released from a system when $2 \text{ moles}$ of an ideal gas are compressed isothermally from a volume of $25 \text{ dm}^3$ to $10 \text{ dm}^3$ at a constant external pressure of $4 \text{ bar}$. (in $\text{ kJ}$)

The conservation of mass and energy is demonstrated by: