Lab Techniques

Question 1

Filtration Technique

Answer 1

Technique used to separate solids from liquids. The two main types of filtration are:

1. Vacuum Filtration: method used to collect solid
2. Gravity Filtration: method used to collect liquid

Question 2

Recrystallization Technique

Answer 2

Technique used to separate solids based on solubility differences. Commonly used to purify an impure compound in a solvent. It is based on the principle that the solubility of most solids increases with increased temperature. Therefore, as temperature increase, the amount of solute that can be dissolved in a solvent increases.

Question 3

Sublimation Technique

Answer 3

Technique used to separate solids based on their ability to sublime. Sublimation is the transition of a substance directly from the solid to the gas phase without passing through the liquid phase. This is a common technique used to purify substances and occurs at temperatures and pressures below the substances triple point.

Question 4

Centrifugation Technique

Answer 4

Technique used to separate substances within heterogenous mixtures based on their mass and density. Heavy/more-dense substances will migrate and settle at the bottom of the centrifuge forming sediment. Light/less-dense substances will migrate and stay suspended in the fluid portion.

Question 5

Distillation Technique

Answer 5

Technique used to separate liquids based on boiling point differences. It involves heating the liquid until it boils (evaporation), then cooling the liquid (condensation) and collecting the resulting vapors. It is used to purify a compound by separating it from a non-volatile or less-volatile material, which is dependent on the intermolecular forces present within the compound.

Question 6

Extraction Technique

Answer 6

Technique used to separate compounds into dissolved substances based upon solubility differences in aqueous vs. organic solvents. In general, polar substances and salts will partition to the aqueous solvent. Non-polar substances will partition to the organic solvents. Underlying assumption: organic solvents are more soluble in organic solvents than in water-based solvents.

Organic solvents = methylene chloride, diethyl ether, ethyl acetate