Question

The change in internal energy of a system (ΔE) can be described in terms of heat (q) and work (w) according to the equation ΔE = q + w.

The conversion of 40 g of liquid H₂O to steam at 1.0 atm leads to an increase in its volume. This expansion exerts 4.545 kJ of work on the surroundings. If the increase in internal energy of the H₂O is 85.724 kJ, how much heat energy does this vaporization process use? (Include the sign of the value in your answer.)

in kJ

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Work (w) is performed by gas expansion at constant pressure (P) according to the equation w = −PΔV where ΔV is the change in volume (V₂ − V₁) of the system. Use this relationship to solve the problem below.

The combustion of 0.25 moles of octane gas (C₈H₁₈) to CO₂ gas and H₂O gas (vapor) against a constant, external pressure of 2.2 atm increases the total volume of gas from 111.0 L to 147.8 L. How much work is performed by this expansion? (Include the sign of the value in your answer.)

in J

Answer 1