At $1 \ bar$ pressure,a gas has a volume of $0.6 \ L$. If this gas gains $122 \ J$ of heat at $1 \ bar$ pressure,its volume becomes $2 \ L$. Calculate its internal energy change. [Given: $1 \ L \cdot bar = 101.32 \ J$]

(N/A) The change in internal energy is given by the first law of thermodynamics: $\Delta U = q + w$.
Here,$q = +122 \ J$ (heat is gained by the system).
The work done by the gas is $w = -P \cdot \Delta V$.
$\Delta V = V_f - V_i = 2 \ L - 0.6 \ L = 1.4 \ L$.
$w = -1 \ bar \times 1.4 \ L = -1.4 \ L \cdot bar$.
Converting work to Joules: $w = -1.4 \times 101.32 \ J = -141.848 \ J$.
Therefore,$\Delta U = 122 \ J - 141.848 \ J = -19.848 \ J \approx -19.85 \ J$.