Concept:Vapor pressure is an intensive thermodynamic property. Intensive properties depend strictly on the intrinsic nature of the substance and temperature, not on its macroscopic scale.
Formula:Not applicable.
Solution:- The vapor pressure of a substance is determined by how forcefully its molecules try to escape into the gas phase. This is controlled by the strength of its Intermolecular forces (which are dictated by the Type of bond).
- However, vapor pressure is an equilibrium ratio. Whether you have 10 mL of water in a beaker or 10,000 Liters of water in a tank, the equilibrium pressure the vapor exerts at a given temperature is mathematically identical.
- Therefore, the physical Amount of liquid has absolutely zero effect on the magnitude of the vapor pressure.
Why other options are incorrect:Intermolecular forces and bond types chemically define the vapor pressure. (Note: External pressure defines the
boiling point threshold, though strictly speaking, the intrinsic vapor pressure curve itself is independent of external pressure. However, in this multiple-choice context, macroscopic "amount" is the universal textbook distractor).
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