Things to note: bonding and structure

10. Methanol, CH₃OH, is miscible with water in all proportions.

Sodium chloride is much less soluble in methanol than water.

Explain these statements using your knowledge of the interactions between solutes and solvents.

You must use diagrams in your answers.

• hydrogen bonding between water / solvent and methanol / solvent

• same strength / comparable to bonding in either component on its own

• hydration of Na⁺ and Cl^-

• the ionic bonding is stronger between sodium and / or chloride ions and methanol

• (and diagrams)

Explain why hydrogen bonding causes ice to be less dense than liquid water.

• more open / more space between molecules (making it less dense)

• due to (3 Dimensional) lattice / ring structure in ice

• hydrogen bonds longer than the covalent bonds

Explain why phenol can be nitrated using milder conditions than benzene.

• the electron density of the (benzene) ring is greater in phenol than in benzene

• because the lone pair of electrons on oxygen overlaps with the pi cloud / delocalised electrons / delocalised system

A mixture of 2-nitrophenol and 4-nitrophenol is produced in Stage 1. They are separated by steam distillation.

The boiling temperature of 2-nitrophenol is 215 degrees C and that of 4-nitrophenol is 279 degrees C. Explain, in terms of intermolecular forces, why 4-nitrophenol has a higher boiling temperature than 2-nitrophenol.

You may include a diagram in your answer.

• they form hydrogen bonds

• in 4-nitrophenol the hydrogen bonds joining molecules in a straight chain / at both ends / at opposite end (of the molecule so are stronger)

OR

• 2-nitrophenol forms intramolecular hydrogen bonds / forces / interactions so fewer intermolecular hydrogen bonds