Answer:
[tex]T = 34.493\,^{\textdegree}C[/tex]
Explanation:
The equilibrium temperature of the gas-container system is:
[tex]Q_{Cu} = -Q_{g}[/tex]
[tex](0.3\,kg)\cdot\left(386\,\frac{J}{kg\cdot ^{\textdegree}C} \right)\cdot (T-20\,^{\textdegree}C) = (1.5\,mol)\cdot \left(12.5\,\frac{J}{mol\cdot ^{\textdegree}C} \right)\cdot (124\,^{\textdegree}C-T)[/tex]
[tex]\left(115.8\,\frac{J}{^{\textdegree}C} \right)\cdot (T-20\,^{\textdegree}C) = \left(18.75\,\frac{J}{^{\textdegree}C} \right)\cdot (124\,^{\textdegree}C-T)[/tex]
[tex]134.55\cdot T = 4641[/tex]
[tex]T = 34.493\,^{\textdegree}C[/tex]