Obtain phase diagrams for water and carbon dioxide. Based on the phase diagram for water, explain how it is possible to skate on ice, that is, solid water.

Verified step by step guidance

1. Observe the phase diagram of water, which shows the states of water (solid, liquid, gas) at different temperatures and pressures.
2. Notice the line separating the solid and liquid phases; this is the melting/freezing line where ice can turn into water and vice versa.
3. When skating on ice, the pressure exerted by the skate blade lowers the melting point of ice, causing a thin layer of water to form under the blade.
4. This thin layer of water acts as a lubricant, allowing the skate to glide smoothly over the ice surface.
5. The phase diagram shows that increasing pressure can shift the equilibrium between solid and liquid, explaining the phenomenon of skating on ice.

Key Concepts

Phase Diagram

A phase diagram is a graphical representation that shows the states of a substance (solid, liquid, gas) at various temperatures and pressures. It illustrates the conditions under which distinct phases occur and coexist, including critical points and phase transitions. Understanding the phase diagram of water is essential for explaining phenomena like skating on ice, as it highlights the relationship between pressure, temperature, and the state of water.

Ice Skating and Pressure

Skating on ice is possible due to the pressure exerted by the skate blade, which lowers the melting point of ice. According to the phase diagram, when pressure is applied to solid ice, it can transition to liquid water even at temperatures below 0°C. This thin layer of liquid water reduces friction, allowing skaters to glide smoothly over the ice, demonstrating the unique properties of water's phase behavior.

Triple Point

The triple point of a substance is the specific temperature and pressure at which all three phases (solid, liquid, and gas) coexist in equilibrium. For water, this occurs at 0.01°C and 0.006 atm. Understanding the triple point is crucial for comprehending the phase transitions of water and how changes in pressure and temperature can lead to different states, which is relevant when discussing the conditions under which ice skating occurs.