How does atmospheric pressure affect the boiling point?

How does atmospheric pressure affect the boiling point?

• A. Lower pressure raises the boiling point.
• B. The boiling point decreases with higher pressure.
• C. Pressure does not affect boiling point.
• D. Higher pressure raises the boiling point.

Answer: (D)

Boiling happens when the liquid’s vapor pressure equals the surrounding atmospheric pressure. If the surrounding pressure is higher, the liquid must reach a higher temperature so its vapor pressure can match that greater pressure, so the boiling point increases. If the pressure is lower, boiling occurs at a lower temperature. This is why a pressure cooker boils water at a higher temperature than at sea level, cooking food faster, while at high elevations water boils below 100°C.

Boiling happens when the liquid’s vapor pressure equals the surrounding atmospheric pressure. If the surrounding pressure is higher, the liquid must reach a higher temperature so its vapor pressure can match that greater pressure, so the boiling point increases. If the pressure is lower, boiling occurs at a lower temperature. This is why a pressure cooker boils water at a higher temperature than at sea level, cooking food faster, while at high elevations water boils below 100°C.