Q3. Give two differences between a true solution and a sol.
A true solution is a single phase, with solute particles mixed evenly among the solvent molecules. A sol is heterogeneous: its dispersed particles, 10−9 to 10−6 m across, are large molecules or clusters of small molecules spread through the dispersion medium (Lab Manual, page 1).
Q4. What are hydrophilic and hydrophobic sols?
They are lyophilic and lyophobic sols in which the dispersion medium is water (Lab Manual, page 1).
Q5. The egg albumin sol starts with 100 mL of a 5% (w/v) sodium chloride solution. What mass of NaCl is that, and what is the molarity? (Na = 23, Cl = 35.5.)
5% (w/v) is 5 g in 100 mL, so 5 g, as the Lab Manual’s list of materials gives. M(NaCl) = 58.5 g mol−1: 5/58.5 = 0.0855 mol in 0.100 L, so about 0.855 M (reasoned).
Q6. The starch sol uses 500 mg of starch in 100 mL of water. What is its concentration in grams per litre, and as a percentage (w/v)?
0.5 g in 0.100 L is 5 g L−1, which is 0.5 g per 100 mL, 0.5% (w/v) (reasoned from the Lab Manual’s quantities, page 2).