IMF RETAKE

Solid carbon tetrachloride, CCl₄, is represented by the diagram above. The attractions between the CCl₄ molecules that hold the molecules together in the solid state are best identified as

• polar covalent bond

• nonpolar covalent compounds

• intermolecular attractions resulting from temporary dipoles

• intermolecular attractions resulting from permanent dipoles

At 298 K and 1 atm, Br₂ is a liquid and Cl₂ is a gas. Those observations provide evidence that under the given conditions, the

• Inter molecular forces among Br₂ molecules are stronger than those among Cl₂ molecules

• forces among Cl₂ molecules are stronger than the Cl-Cl bond

• Br-Br bond is stronger than the Cl-Cl bond

• Cl-Cl bond is stronger than the Br-Br bond

Based on the structural formulas, which of the following identifies the compound that is more soluble in water and best helps to explain why?

• Ethane, because the electron clouds of its molecules are more polarizable than those of propanol.

• Ethane, because its molecules can fit into the spaces between water molecules more easily than those of propanol can.

• Propanol, because its molecules have a greater mass than the molecules of ethane have.

• Propanol, because its molecules can form hydrogen bonds with water molecules.

Based on the information in the table above, which of the compounds has the highest boiling point, and why?

• Butanal, because it can form intermolecular hydrogen bonds

• Pentane, because it has the longest carbon chain

• Pentane, becaue it has the most C-H bonds

• Propanoic acid, because it can form intermolecular hydrogen bonds

If the pressure of each gas is increased until condensation occurs, which gas will condense first?

• methane

• Ethane

• Butane

• All the gases will condense at the same pressure.

The structural formulas for two isomers of 1,2-dichloroethene are shown above. Which of the two liquids will evaporate first and why?

• The cis-isomer, because it has dipole-dipole interactions, whereas the trans-isomer has only London dispersion forces

• The cis-isomer, because it has only London dispersion forces, whereas the trans-isomer also has dipole- dipole interactions

• The trans-isomer, because it has dipole-dipole interactions, whereas the cis-isomer has only London dispersion forces

• The trans-isomer, because it has only London dispersion forces, whereas the cis-isomer also has dipole- dipole interactions

The London (dispersion) forces are weakest for which of the following gases under the same conditions of temperature and pressure?

• H₂

• O₂

• Xe

• F₂

• N₂

The diagram above is a molecular model of Oxygen gas

(O₂ )that is just above its boiling point. Intermolecular forces between the gas molecules will cause them to condense into the liquid phase if the temperature is lowered. Which of the following best describes how the model is limited in its depiction of the phenomenon?

• It does not show how hydrogen bonds are constantly forming, breaking, and reforming, which results in a net force of attraction between the molecules.

• It does not show how the interactions between ions and the induced molecular dipoles result in a net force of attraction between the molecules.

• It does not show how the interacting permanent dipoles of the molecules result in a net force of attraction between the molecules.

• It does not show how the temporary fluctuating dipoles of the molecule result in a force of attraction between the molecules.

Consider the molecules represented abov. Nonane and 2,3,4-trifluoropentane have almost identical masses, but nonane has a significantly higher boiling point. Which of the following statements best helps explain this observation?

• The C–F bond is easier to break than the C–H bond.

• The C–F bond is more polar than the C–H bond.

• The carbon chains are longer in nonane than they are in 2,3,4-trifluoropentane.

• The carbon chains are farther apart in a sample of nonane than they are in 2,3,4- trifluoropentane.

Which of the following best helps to explain why CCl₄ carbon tetrachloride is a liquid whereas CI₄ (carbon tetraiodide) is a solid when both are at 25°C?

• The dipole of the CCl₄ molecule is larger than that of the CI₄ (carbon tetraiodide) molecule because chlorine is more electronegative than iodine.

• The dipole moment of the CI₄ (carbon tetraiodide) molecule is larger than that of the CCl₄ (carbon tetrachloride) molecule because there is stronger repulsion between electrons in the C-I bonds compared to the repulsion between electrons in the C- Cl bonds.

• The London dispersion forces are stronger in CCl₄ (carbon tetrachloride) than in CI₄ (crabon tetraiodide) because chlorine is more electronegative than Iodine,

• The London dispersion forces are stronger in CI₄ (carbon tetraiodide) than in CCl₄ (carbon tetrachloride) because CI₄ (carbon tetraiodide) has a more polarizable (larger) electron cloud than CCl₄ (carbon tetrachloride)