Chapter 23, Problem 51A

Hydrothermal vents are openings in the ocean floor that discharge very hot water. Water emerging at nearly $280°C$ from one such vent off the Oregon coast, some 2400 m beneath the surface, is not boiling. Provide an explanation.

Solution

To Explain: Water emerging from a hydrothermal vent in the ocean is not boiling at a temperature of $280°\text{C}$ .

The water emerging from a hydrothermal vent is not boiling at a temperature of $280°\text{C}$ because of high pressure at that point.

Introduction: Boiling point is that temperature at which a substance changes its state from liquid to gas at that particular pressure. The boiling point of water at atmospheric pressure is $100°\text{C}$ .

Explanation:

Hydrothermal vents are locations at the base of sea where water erupts along with minerals in superheated form. These locations are generally nearby the boundaries of tectonic plates or active volcanoes.

As the pressure increases, the molecules of the substance come closer to each other and it requires more energy to expand to the gaseous state. So, the temperature required to change the state increases and hence the boiling point of water increases with the increase in pressure on it.

As the hydrothermal vents are very deep inside the earth i.e. around 2400m, the pressure at such a depth is very high and boiling point is also very high.

So due to this water being at $280°\text{C}$ is not boiling.

Conclusion:

The water emerging from a hydrothermal vent is not boiling at a temperature of $280°\text{C}$ because of high pressure at that point.