Exam 10: Intermolecular Forces: The Uniqueness of Water

Which of the following statements does not correctly identify a factor that affects the boiling point of a pure substance? I. vapor pressure of the liquid II. strength of intermolecular forces III. enthalpy of vaporization IV. surface area of the liquid

Portable lanterns and stoves used for camping often use a mixture of hydrocarbons for fuel. One such hydrocarbon is an alkane called n-pentane. These lanterns and stoves are often difficult to light on a cold day because the fuel has a low vapor pressure at low temperatures. Determine the vapor pressure of n-pentane on a night when the temperature is 0.0C. The enthalpy of vaporization of n-pentane is 27.6 kJ/mol, and its boiling point is 36.0C.

Which alkane compound has the highest vapor pressure?

The phase diagram for carbon dioxide is shown below. What is the phase that exists at room temperature and pressure (22^oC, 1 atm)?

Which one of the following substances would you predict to have the highest vapor pressure at a given temperature? In these line drawings, a carbon is implicit at the end of a line (bond) or where two or more lines come together. Carbon requires four bonds, so any missing bonds are implicitly bonds to hydrogen atoms.

Which compound do you predict has the lowest boiling point?

Which of the following substances would you expect to have the largest van der Waals a constant value?

Which alkane compound has the lowest vapor pressure?

The concept "like dissolves like" explains why

Which one of the following substances would you predict to have the highest boiling point? In these line drawings, a carbon is implicit at the end of a line (bond) or where two or more lines come together. Carbon requires four bonds, so any missing bonds are implicitly bonds to hydrogen atoms.

The relative energies (strengths) of the intermolecular forces present in each of four different pure substances are shown in the figure below. Which substance has the highest melting point?

Would water rise to the same height in a capillary tube made of polyethylene plastic as it does in a glass capillary tube of the same diameter? Polyethylene is a hydrocarbon, and glass is mostly silicon dioxide. Explain.

Gasoline is primarily a mixture of hydrocarbons and is sold with an octane rating that is based on a comparison with the combustion properties of isooctane. Gasoline usually contains an isomer of isooctane called tetramethylbutane (C₈H₁₈), which has an enthalpy of vaporization of 43.3 kJ/mol and a boiling point of 106.5C. Determine the vapor pressure of tetramethylbutane on a very hot summer day when the temperature is 38C.

The temperature at point a in the phase diagram below is the ________

The pressure of carbon dioxide in a beer bottle is about 2 atm. At this pressure about 0.15 g of carbon dioxide dissolves in 100 mL of beer. How much carbon dioxide remains dissolved in 100 mL after the bottle is opened? The partial pressure of carbon dioxide is 2.0 10^4 atm.

Which liquid, water or ethanol, would you expect to have the higher surface tension and viscosity? Explain.

Water forms a concave meniscus in a glass tube because ________

Polarizability refers to ________

The relative energies (strengths) of the intermolecular forces present in each of four different pure gases are shown in the figure below. a) Which gas will show the smallest deviation from ideal gas behavior? b) Which substance has the lowest melting point? c) Which substance is most likely to be a solid at room temperature?

The vapor pressure of a liquid will increase if ________