C6 - Purification and Yield Flashcards
What is the purpose of purification and isolation?
To isolate the product from the reaction mixture.
How does evaporation work?
The soluble product is separated from the solute through heating it to leave crystals. Purification is involved as impurities cannot fit in the crystals. This purity is increased through redissolving the solution and evaporating it - recrystallisation.
How does filtration work?
The insoluble solid is isolated from the solute with filter paper. This is used to filter aspirin from liquid reactants and impurities are also filtered out.
How does drying work to isolate products?
Hot ovens are used where hot air is blown over the product or heated to remove excess moisture.
Desiccators are containers with silica gel which absorb moisture from the product.
What is percentage yield? How is it calculated?
This is the actual product as a percentage of the theoretical yield. Divide the mass of the pure, dry product by the theoretical yield, the maximum possible yield of a pure product calculated with a balanced equation, and multiply by 100.
Why is percentage yield never 100%?
Product is lost through processes of filtration and purification
