A rigid, well-insulated container initially holds only liquid Br at its normal…
CHEMISTRY · Single correct · A Level · Chemistry · Thermodynamics · Thermodynamics
Problem
A rigid, well-insulated container initially holds only liquid Br2 at its normal boiling point. Exactly one-half of the liquid is allowed to vaporize while the temperature is maintained at the boiling point by an external heat source. Which statement best describes the overall entropy change, ΔS, of the Br2 in the container?
(a) ΔS=0, because the temperature remains constant during the phase change.
(b) ΔS<0, because the vapor formed must occupy the same fixed volume, decreasing the freedom of the particles.
(c) ΔS>0, because converting some liquid to gas increases molecular disorder even though the temperature is constant.
(d) The sign of ΔS cannot be predicted without knowing the enthalpy of vaporization of Br2.