In a power-plant condenser, steam at 100 °C and 1 atm is first converted to liquid water at 100 °C and then cooled further until the water freezes at 0 °C, all at 1 atm. The process is carried out on exactly 1 mol of H₂O.
(a) For each step—condensation (steam → liquid) and freezing (liquid → solid)—state the algebraic sign of ΔH. Explain your reasoning in terms of energy flow.
(b) Compare the magnitude of ΔH for condensation with that for vaporization of 1 mol of water under the same pressure. Provide an explanation for any relationship you identify.
(c) Explain why the magnitudes of ΔH for condensation and freezing are not equal, even though both processes involve the removal of heat from the system.
(d) If the frozen water were subsequently warmed to 0 °C and then vaporized back to steam at 100 °C, describe qualitatively the net heat exchange for the complete cycle and relate your answer to the principle of conservation of energy.