Question

When 2. 0 mol CO2 is heated at a constant pressure of 1. 25 atm, its temperature increases from 250 K to 277 K. Given that the molar heat capacity of CO2 at constant pressure is 37. 11 JK-1mol-1 , calculate q, ∆ H and ∆ U

Answer 1

Answer: See below

Explanation:

$\mathrm{At \ constant \ pressure \ the \ heat \ generated \ and \ change \ in \ enthalpy \ are \ equal:} \\\begin{aligned}Q &=\Delta H=n C_{p} \Delta T \\&=2 \times(37.11)(277-250) \\&=2003.94 \mathrm{~J} \\Q &=\Delta H=2.0 \times 10^{3} \mathrm{~J}\end{aligned}$

$\mathrm{Calculate \ the \ change \ in \ internal \ energy:} \\ \begin{aligned}\Delta H &=\Delta U+\Delta(P V) \\\Delta U &=\Delta H-n R \Delta T \\&=(2003.94)-(2 \times 8.314 \times(277-250)) \\&=(2003.94)-(448.96) \\\Delta U &=1554.98 \mathrm{~J}\end{aligned}$