Question

150g of a gas at 10.0°C and 1.0 atm pressure occupies 913L volume. The volume of the gas increases to 988L and its temperature increases to 41.5°C while the pressure remains constant. Calculate ΔE, q and w for the gas. (Specific heat of the gas = 5.2J/g°C and 1L.atm = 101.3J). [4 marks]

Answer 1

ΔE = q + w - the first law of thermodynamics.

$q=c\cdot m\cdot\Delta T=5.2J/g°C\cdot150g \cdot(41.5°C-10°C)=24570J$

$w=-p\cdot \Delta V=-1atm\cdot(988L-913L)=-75L\cdot atm=-75\cdot 101.3J=-7597.5J\approx7598J$

$\Delta E=q+w=24570J-7598J=16972J$

Answer:

$\Delta E=16975J$

$q=24570J$

$w=7598J$