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The vapor pressure of methanol is 143 mmHg. Identify the best reason to explain

ID: 517056 • Letter: T

Question

The vapor pressure of methanol is 143 mmHg. Identify the best reason to explain why methanol spontaneously evaporates in open air at 25.0?Cand standard pressure (760 mmHg)

The vapor pressure of methanol is 143 . Identify the best reason to explain why methanol spontaneously evaporates in open air at 25.0 and standard pressure (760 ).

Heat can be added under these nonstandard conditions to increase the vapor pressure of methanol. Calculations for a closed container show a partial pressure of methanol lower than its vapor pressure. The calculated standard free energy change corresponds to a spontaneous reaction. Under these nonstandard conditions, the partial pressure of methanol is lower than its vapor pressure.

Explanation / Answer

Option 'C' gives correct explanation for its spontaneous evaporation.

At low pressures of methanol, the phase transition is spontaneous as delta G(free energy) value is negative.

So as long as system is open to air so that pressure of methanol can't increase, the methanol evaporate.

Thank you