Worksheet: Physical Effects of Intermolecular Forces

In this worksheet, we will practice describing the effect of intermolecular forces on properties such as hardness, solubility, and melting and boiling points.

Q1:

In which of the following sequences are the compounds arranged in order of increasing boiling point?

  • A C H < C H < C H 2 6 4 3 8
  • B C H < C H < C H 4 3 8 2 6
  • C C H < C H < C H 3 8 2 6 4
  • D C H < C H < C H 4 2 6 3 8
  • E C H < C H < C H 3 8 4 2 6

Q2:

The boiling points of hydrogen halides increase in the order HCl < HBr < HI < HF.

Which interactions are responsible for the difference between the boiling points of HCl and HF?

  • ADipole–dipole attractions
  • BDispersion forces
  • CHydrogen bonds
  • DIon–dipole attractions
  • EIonic bonds

Which interactions are responsible for the difference between the boiling points of HCl and HBr?

  • ADipole–dipole attractions
  • BIonic bonds
  • CHydrogen bonds
  • DIon–dipole attractions
  • EDispersion forces

Q3:

Why is vegetable oil immiscible with water, based on the intermolecular interactions?

  • AThe water–oil interactions are weaker than the sum of the water–water and oil–oil interactions.
  • BMixing of oil and water is entropically unfavorable, as water molecules must form highly ordered shells around dissolved oil molecules.
  • CMolecules of oil pack more efficiently with each other, as they are much larger in size than molecules of water.
  • DThe formation of an oil layer at the surface of the liquid is favorable, as the surface energy of oil is lower than that of water.
  • EWater only dissolves ionic substances.

Q4:

Which of the following molecules forms the strongest hydrogen bonds?

  • A H I
  • B H F
  • C H B r
  • D H 2
  • E H C l

Q5:

Two diatomic molecules interact via dispersion forces. In general, which of the following quantities could be increased to increase the strength of the dispersion forces?

  • AMolecular charge
  • BBond energy
  • CTemperature
  • DBond polarity
  • EAtomic size

Q6:

Which of the following noble gases has the highest boiling point?

  • A N e
  • B X e
  • C A r
  • D K r
  • E H e

Q7:

In which of the following sequences are the compounds arranged in order of increasing boiling point?

  • A H C l < H O < S i H 2 4
  • B S i H < H C l < H O 4 2
  • C H C l < S i H < H O 4 2
  • D H O < H C l < S i H 2 4
  • E S i H < H O < H C l 4 2

Q8:

Why does the viscosity of a liquid decrease with heating?

  • AThe conformations of molecules become more linear.
  • BIntramolecular bonds are weakened.
  • CIntermolecular bonds are weakened.
  • DThe vapor pressure of the liquid increases.
  • EIntramolecular bonds vibrate more rapidly.

Q9:

What happens to the surface tension and viscosity of water with increasing temperature?

  • AViscosity decreases and surface tension increases.
  • BViscosity and surface tension both increase.
  • CViscosity and surface tension are both constant.
  • DViscosity increases and surface tension decreases.
  • EViscosity and surface tension both decrease.

Q10:

The density of liquid diethyl ether at standard temperature and pressure is 0.713 g/cm3. The density of gaseous diethyl ether vapor under the same conditions is 0.003 g/cm3. Which interactions are mainly responsible for the difference between the densities of the two phases?

  • ADispersion forces
  • BHydrogen bonds
  • CIon–dipole attractions
  • DIonic bonds
  • EDipole–dipole attractions

Q11:

The density of liquid phosphine (PH)3 at 90C and a pressure of 1 bar is 0.746 g/cm3. The density of gaseous diethyl ether vapor under the same conditions is 0.002 g/cm3. Which interactions are mainly responsible for the difference between the densities of the two phases?

  • AHydrogen bonds
  • BIon–dipole attractions
  • CDispersion forces
  • DDipole–dipole attractions
  • EIonic bonds

Q12:

Why is the enthalpy of vaporization of ethane higher than that of methane?

  • AThe ethane molecule has a larger area to interact with neighboring molecules via dispersion forces.
  • BThe more elongated shape of the ethane molecule allows for more densely packed molecular arrangements.
  • CThe ethane molecule has a larger dipole moment, so it interacts more strongly with neighboring molecules via dipole–dipole attractions.
  • DThe ethane molecule has a larger area to interact with neighboring molecules via hydrogen bonding.
  • EThe lower symmetry of the ethane molecule destabilizes molecular clusters removed from the liquid surface during vaporization.

Q13:

The boiling point of ethanoic acid is greater than that of 1-propanol. Which interactions are mainly responsible for this difference?

  • AHydrogen bonds
  • BDispersion forces
  • CDipole–dipole attractions
  • DIon–dipole attractions
  • EIonic bonds

Q14:

For which of the following pairs of compounds is the difference in melting point mostly due to differences in the strength of hydrogen bonding?

  • ADichloromethane and chloroform
  • B 𝑛 -Hexane and cyclohexane
  • C1-Chloropropane and 2-chloropropane
  • DLithium hydride and sodium hydride
  • E 𝑛 -Butane and 1-butanol

Q15:

How does increasing the strength of intermolecular forces typically affect the surface tension and vapor pressure of a liquid?

  • ASurface tension decreases and vapor pressure increases.
  • BBoth quantities decrease.
  • CBoth quantities remain constant.
  • DSurface tension increases and vapor pressure decreases.
  • EBoth quantities increase.

Q16:

In which of the following sequences are the compounds arranged in order of increasing boiling point?

  • A F < B r < C l 2 2 2
  • B B r < C l < F 2 2 2
  • C F < C l < B r 2 2 2
  • D C l < B r < F 2 2 2
  • E C l < F < B r 2 2 2

Q17:

In which of the following sequences are the compounds arranged in order of increasing boiling point?

  • A S i H < H S < P H 4 2 3
  • B S i H < P H < H S 4 3 2
  • C P H < H S < S i H 3 2 4
  • D P H < S i H < H S 3 4 2
  • E H S < P H < S i H 2 3 4

Q18:

Which of the following properties of a liquid solution is not a consequence of evaporation?

  • AThe liquid volume in an open container decreases over time.
  • BThe liquid rises in a capillary tube.
  • CSolute crystals form on the side of the container above the liquid surface.
  • DThe liquid has a detectable smell.
  • EDroplets form on the side of the container above the liquid surface.

Nagwa uses cookies to ensure you get the best experience on our website. Learn more about our Privacy Policy.