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 that the line separating the solid and liquid phases has a negative slope, indicating that increasing pressure can cause ice to melt at temperatures below the normal freezing point.
3. When skating on ice, the pressure exerted by the skate blade on the ice surface increases the pressure locally, which can cause the ice to melt and form a thin layer of water.
4. This thin layer of water reduces friction, allowing the skate to glide smoothly over the ice surface.
5. Once the pressure is removed, the water refreezes, maintaining the solid state of the 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 phase diagrams is essential for predicting how a substance behaves under different environmental conditions.

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. This concept is crucial for understanding the unique properties of water, including its ability to skate on ice, as it highlights the delicate balance between solid and liquid states.

Pressure and Ice Skating

When skating on ice, the pressure exerted by the skate blade can lower the melting point of ice, causing a thin layer of liquid water to form. This phenomenon occurs because the phase diagram indicates that at higher pressures, ice can transition to liquid at temperatures below 0°C. This liquid layer reduces friction, allowing skaters to glide smoothly over the ice.