Bonding - Solubility

Question 1

Name three chemical forces (bonding types) that occur within a sample of water

Answer 1

Covalent bonds (within molecules), Hydrogen bonds (between molecules), Dispersion forces (between molecules)

Question 2

What description is used for two liquids that can ‘dissolve’ each other?

Answer 2

Miscible

Question 3

What happens to chemical forces when an ionic compound dissolves in water?

Answer 3

Forces between ions (ionic bonds) are broken, forces between water molecules (hydrogen bonds and dispersion forces) are broken, forces between ions and water molecules (ion-dipole forces) are formed.

Question 4

What new forces form when ethanol molecules dissolve in water?

Answer 4

Hydrogen bonds (between the ethanol and water molecules)

Question 5

What forces can form between a polar and a non-polar molecule?

Answer 5

Dispersion forces

Question 6

What are the two phases in any chromatography experiment?

Answer 6

Mobile phase and stationary phase

Question 7

Why should a paper chromatography baseline be drawn in pencil?

Answer 7

Pencil lines are insoluble so the baseline won’t run up the paper.

Question 8

What description is used when a substance ‘sticks’ to the stationary phase in chromatography?

Answer 8

Adsorption

Question 9

If a substance has a high Rf value, is it likely to have high or low solubility in the solvent used?

Answer 9

High solubility

Question 10

What are the highest and lowest possible Rf values, and when do they occur?

Answer 10

1.0 (a soluble component travels with the solvent front) and 0.0 (an insoluble component stays on the baseline)