Using the phase diagram for [tex]H _2 O[/tex], what phase is water in at 1 atm pressure and [tex]$-5^{\circ} C$[/tex]?
A. It is at its melting point.
B. It is in the gas phase.
C. It is in the liquid phase.
D. It is in the solid phase.
Answer (2)
The problem requires determining the phase of water at 1 atm and − 5 ∘ C .
Since − 5 ∘ C is below the freezing point of water, it will be in solid phase.
Therefore, the answer is that water is in the solid phase.
The final answer is D .
Explanation
Understanding the Problem The problem asks us to determine the phase of water ( H 2 O ) at a pressure of 1 atm and a temperature of − 5 ∘ C using its phase diagram. We need to identify which phase (solid, liquid, or gas) water exists in under these conditions.
Determining the Phase At 1 atm pressure and 0 ∘ C , water is at its melting/freezing point. Since the temperature in the problem is − 5 ∘ C , which is below the freezing point, the water will be in the solid phase (ice).
Conclusion Therefore, at 1 atm pressure and − 5 ∘ C , water is in the solid phase.
Examples
Understanding phase diagrams is crucial in many real-world applications. For example, in food science, it helps determine the optimal conditions for preserving food by freezing. In materials science, it aids in understanding the behavior of different materials under varying temperatures and pressures, which is essential for designing durable structures. Moreover, in environmental science, it helps predict the state of water in different climates, such as whether it will be ice, liquid water, or vapor.
Water at 1 atm pressure and -5°C is in the solid phase, which is ice. Since -5°C is below the freezing point of water (0°C), it cannot exist as a liquid at these conditions. Thus, the correct choice is D.
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