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Enthalpy Change and Pressure-Volume Work

A gas is compressed from an initial volume of \mathrm{0.04 m^{3}} to a final volume of \mathrm{0.02 m^{3}} at a constant pressure of \mathrm{5 atm}. During this process, it releases \mathrm{800 J} of heat to the surroundings. Calculate the change in enthalpy of the gas

Option: 1

\mathrm{9332.5 J}


Option: 2

\mathrm{564.40 J}


Option: 3

\mathrm{245.20 J}


Option: 4

\mathrm{687.35 J}


Answers (1)

best_answer

The change in enthalpy \mathrm{(\Delta H)} is given by:

\mathrm{ \Delta H=Q-P \Delta V }

Given:

\mathrm{ Q =-800 \mathrm{~J} \quad } (negative because heat is released)

\mathrm{ P =5 \mathrm{~atm} \quad }    (pressure)

\mathrm{ \Delta V =V_f-V_i=0.02 \mathrm{~m}^3-0.04 \mathrm{~m}^3=-0.02 \mathrm{~m}^3 } (negative due to compression)

Substitute the values into the formula:

\mathrm{ \Delta H=-800 \mathrm{~J}-(5 \mathrm{~atm}) \cdot\left(-0.02 \mathrm{~m}^3\right) \cdot 101325 \mathrm{~Pa} / \mathrm{atm} }

\mathrm{ \Delta H=-800 \mathrm{~J}+10132.5 \mathrm{~J} }

\mathrm{ \Delta H=9332.5 \mathrm{~J} }

Therefore, the correct option is 1.

Posted by

himanshu.meshram

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