1.5 Phase changes  (Page 7/20)

A pressure cooker contains water and steam in equilibrium at a pressure greater than atmospheric pressure. How does this greater pressure increase cooking speed?

As shown below, which is the phase diagram for carbon dioxide, what is the vapor pressure of solid carbon dioxide (dry ice) at $\mathrm{-78.5}\text{°}\text{C}?$ (Note that the axes in the figure are nonlinear and the graph is not to scale.)

Can carbon dioxide be liquefied at room temperature ( $20\text{°}\text{C}$ )? If so, how? If not, why not? (See the phase diagram in the preceding problem.)

What is the distinction between gas and vapor?

Heat transfer can cause temperature and phase changes. What else can cause these changes?

How does the latent heat of fusion of water help slow the decrease of air temperatures, perhaps preventing temperatures from falling significantly below $0\text{°}\text{C,}$ in the vicinity of large bodies of water?

What is the temperature of ice right after it is formed by freezing water?

If you place $0\text{°}\text{C}$ ice into $0\text{°}\text{C}$ water in an insulated container, what will the net result be? Will there be less ice and more liquid water, or more ice and less liquid water, or will the amounts stay the same?

What effect does condensation on a glass of ice water have on the rate at which the ice melts? Will the condensation speed up the melting process or slow it down?

In Miami, Florida, which has a very humid climate and numerous bodies of water nearby, it is unusual for temperatures to rise above about $38\text{°}\text{C}$ ( $100\text{°}\text{F}$ ). In the desert climate of Phoenix, Arizona, however, temperatures rise above that almost every day in July and August. Explain how the evaporation of water helps limit high temperatures in humid climates.

In winter, it is often warmer in San Francisco than in Sacramento, 150 km inland. In summer, it is nearly always hotter in Sacramento. Explain how the bodies of water surrounding San Francisco moderate its extreme temperatures.