What thermodynamic effect accompanies an increase in fluid pressure _________________?
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Answer: B. raises the boiling point of a liquid
Explanation
Increasing external pressure on a liquid raises its boiling point because higher temperatures are required for vapor pressure to equal ambient pressure. Molecules require more thermal energy to escape into the gas phase when constrained by higher external atmospheric pressures. This fundamental thermodynamic principle explains why liquids boil at lower temperatures at high altitudes where pressure is reduced. Boiling point occurs when the vapor pressure of a liquid equals the surrounding external pressure pressing down upon its surface. Phase change thermodynamics dictates that pressure and temperature coordinates along liquid-vapor saturation curves are directly linked. Clausius-Clapeyron relations mathematically describe how saturation boiling temperatures change in response to applied system pressures.
Lowering the boiling point describes the effect of reducing external pressure, which is the opposite of pressure increases. Stating that pressure does not affect boiling point contradicts basic phase change thermodynamics and experimental physics. Reducing volume is a mechanical compressibility effect rather than the primary thermal boiling point shift phenomenon.
- Subject
- Engineering
- Category
- Mechanical Engineering
- Topic
- —
- Difficulty
- medium
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