Core Practical: Investigating Inks Flashcards

All 5 cards in this deck

In the ink chromatography core practical, why is the start line drawn in pencil?

Pencil is insoluble in the solvent, so it will not run up the paper and spoil the results (ink would).

Why must the pencil start line be above the level of the solvent in the beaker?

So the ink spots do not dissolve away into the solvent instead of travelling up the paper.

What improvement to simple distillation apparatus increases the amount of distillate collected?

Use a (Liebig) condenser, or surround the collecting test tube with iced water — this cools the vapour more effectively so more of it condenses.

Why is a flammable solvent such as ethanol heated with a water bath rather than a Bunsen burner?

Its vapour is flammable and could catch fire from the naked flame.

In the ink core practical, how does simple distillation help identify the ink's solvent?

The solvent boils off and is collected, and the thermometer shows the temperature it boils at. Comparing this boiling point with known values identifies the solvent, e.g. a reading of about 78 °C suggests ethanol.