The boiling point of a substance is defined as the temperature at which liquid a

Question

The boiling point of a substance is defined as the temperature at which liquid and vapor coexist in equilibrium. Use the heat of vaporization (deltaHvap=30.91kJ/mol) and the entropy of vaporization boiling point [deltaSvap=93.2J/(k*mol)] to calculate the boiling point (deg C) of liquid bromine.
For any process in _____________, Gibbs free energy is equal to ______________. The change in enthalpy for this process is ______________kJ/mol (4 significant figures). The boiling point of liquid bromine is ____________ deg C (4 sig. Figs). The boiling point of a substance is defined as the temperature at which liquid and vapor coexist in equilibrium. Use the heat of vaporization (deltaHvap=30.91kJ/mol) and the entropy of vaporization boiling point [deltaSvap=93.2J/(k*mol)] to calculate the boiling point (deg C) of liquid bromine.
For any process in _____________, Gibbs free energy is equal to ______________. The change in enthalpy for this process is ______________kJ/mol (4 significant figures). The boiling point of liquid bromine is ____________ deg C (4 sig. Figs).
For any process in _____________, Gibbs free energy is equal to ______________. The change in enthalpy for this process is ______________kJ/mol (4 significant figures). The boiling point of liquid bromine is ____________ deg C (4 sig. Figs).

Explanation / Answer

Consider the following equation:
?G = ?H - T?S
When ?G is negative, a reaction in spontaneous. Clearly, if ?H and ?S are both positive, ?G is only negative, and the reaction is only spontaneous at some temperatures, and at a certain point, ?G goes from negative to positive, and the reaction is no longer spontaneous. For a process such as evaporation, this point (when ?G = 0) occurs at the boiling point temperature. When T is higher, ?G is negative and evaporation is spontaneous; when T is lower, ?G is positive and boiling is not spontaneous.
?G = 0 = ?H - T?S
0 = 30910 J - T(93.2 J/K)
93.2T = 30910
T = 331.652 K

For any process in   equilibrium, Gibbs free energy is equal to 0 . The change in enthalpy for this process is 30.91   kJ/mol (4 significant figures). The boiling point of liquid bromine is 58.65 deg C (4 sig. Figs).

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