Question

question 4 (4 points)
(03.06 mc)
what is the strongest intermolecular force between an nacl unit and an h₂o molecule together in a solution?
covalent bonding
b dipole-dipole force
c hydrogen bonding
d lon-dipole force
question 5 (4 points)
(03.06 mc)
the boiling points of diatomic halogens are compared in the table.
boiling points of
diatomic halogens
molecule boiling point
f₂ -188 °c
cl₂ -34 °c
br₂ 59 °c
i₂ 184 °c
diatomic bromine has weaker intermolecular forces than diatomic iodine.
a true
b false

Explanation:

Question 4

• Covalent bonding is within a molecule (intramolecular), not an intermolecular force.
• \(H_2O\) is a polar molecule (has a dipole). \(NaCl\) dissociates into \(Na^+\) and \(Cl^-\) ions in solution.
• Ion - dipole force occurs between an ion (\(Na^+\) or \(Cl^-\)) and a polar molecule (\(H_2O\)).
• Dipole - dipole force is between two polar molecules (not involving ions). Hydrogen bonding is a special case of dipole - dipole force (between \(H\) bonded to \(N\), \(O\), or \(F\) and another electronegative atom).

• The strength of intermolecular forces (London dispersion forces for non - polar diatomic halogens) is related to molar mass.
• Higher molar mass leads to stronger London dispersion forces.
• \(Br_2\) has a lower molar mass (\(159.8\ g/mol\)) than \(I_2\) (\(253.8\ g/mol\)).
• Substances with stronger intermolecular forces have higher boiling points. Since \(Br_2\) has a lower boiling point (\(59^{\circ}C\)) than \(I_2\) (\(184^{\circ}C\)), \(Br_2\) has weaker intermolecular forces.

Answer:

d. Ion - dipole force

Question 5