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Ch.11 - Liquids, Solids & Intermolecular Forces
Chapter 11, Problem 96

Consider a planet where the atmospheric pressure at sea level is 2500 mmHg. Does water behave in a way that can sustain life on the planet?

Verified step by step guidance
1
Understand the problem: We need to determine if water can exist in a liquid state under the given atmospheric pressure of 2500 mmHg, which is crucial for sustaining life.
Recall the concept of boiling point: The boiling point of a liquid is the temperature at which its vapor pressure equals the external pressure.
Use the known data: On Earth, water boils at 100°C under 760 mmHg. We need to find the boiling point of water under 2500 mmHg.
Apply the Clausius-Clapeyron equation: This equation relates the change in vapor pressure with temperature, which can help estimate the boiling point under different pressures.
Consider the implications: If the boiling point is too low or too high, it might affect the ability of water to sustain life as we know it.

Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Atmospheric Pressure

Atmospheric pressure is the force exerted by the weight of air above a given point. At sea level on Earth, this pressure is approximately 760 mmHg. A pressure of 2500 mmHg, as mentioned in the question, is significantly higher, which can affect the boiling point of water and the solubility of gases, both of which are crucial for sustaining life.
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Boiling Point of Water

The boiling point of water is the temperature at which it transitions from liquid to gas. This point is influenced by atmospheric pressure; higher pressures raise the boiling point. On the hypothetical planet with 2500 mmHg pressure, water would boil at a much higher temperature than 100°C, potentially impacting biological processes that rely on liquid water.
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Solubility of Gases in Water

The solubility of gases in water is affected by temperature and pressure. Generally, higher pressure increases the solubility of gases, which is essential for aquatic life that relies on dissolved oxygen. In an environment with 2500 mmHg, while oxygen may be more soluble, the altered boiling point and other factors could create challenges for life forms that depend on specific gas concentrations.
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