AP Chem semester test

At 20^C, the vapor pressure of toluene is 25 millimeters of mercury. An ideal solution, equimolar in toluene and benzene, is prepared. At 20^C what is the mole fraction of benzene in the vapor in equilibrium with this solution?

0.75

(Graph) The solid and the liquid coexist at

All points on the curve between Q and S

In which of the following processes are covalent bonds broken?

C(diamond)-->C(g)

Which of the following is true for any substance undergoing the process represented above at its normal melting point?

Delta H=T(delta S)

On a mountaintop, it is observed that water boils at 90^C, not at 100^C as at sea level. This phenomenon occurs because on the mountaintop the

Equilibrium water vapor pressure equals the atmospheric pressure at a lower temperature

The difference in boiling points may be attributed to a difference in

Hydrogen bonding

In solid methane, the forces between neighboring CH4 molecules are best characterized as

London (dispersion) forces

Which of the following actions would be likely to change the boiling point of a sample of a pure liquid in an open container?

Moving the container and liquid to a higher altitude

(Graph) The substance is at its normal freezing point at time

T2

Which of the following statements best accounts for the difference in solubility among noble gases?

The gases become more soluble as the molar mass increases

(Graph) Which of the following best describes what happens to the substance at t4?

The molecules are leaving the liquid phase

A pure liquid in an open vessel boils at the temperature at which the

Vapor pressure of the liquid becomes equal to the atmospheric pressure on the surface of the liquid

Based on concepts of polarity and hydrogen bonding, which of the following sequences correctly lists the compounds above in the order of their increasing solubility in water?

X<Y<Z