Practical Skills and Techniques (U3, c3/4) Flashcards
What does volumetric analysis involve?
Using a standard solution in a quantitative reaction to determine the concentration of the other reactant.
What kind of substance is colorimetry useful for?
Coloured compounds.
What must be prepared firstly to determine concentration in colorimetry?
A calibration curve.
What is distillation used for?
To purify a compound by separating if from a non-volatile or less volatile material.
Steam distillation is a special type of distillation for what kind of material?
Temperature sensitive materials, like natural aromatic compounds.
What is fractional distillation?
The separation of a mixture into its component parts, or “fractions”.
What is refluxing for?
Applying heat energy to a chemical reaction mixture over an extended period of time.
What happens in methods of vacuum filtration that makes it different from normal filtration?
These methods are carried out under reduced pressure and provide a faster means of separating the precipitate from the filtrate.
What is hot filtration mainly used for, and why?
To separate solids from a hot solution, done in order to prevent crystal formation in the filter funnel.
What is recrystallisation used for?
Purifying solids based on solubility.
What things are needed of a solvent for recrystallisation?
It must be so the impure compound in insoluble at low temperatures, but soluble at high temperatures.
The boiling point of the solvent must not be too low.
What can be an application of the partition of a solute between two liquids?
Solvent extraction.
What is the partition coefficient?
The concentration of a solute in the organic layer over that in the aqueous layer.
What is the largest risk when using a separating funnel? How can this be easily handled?
Pressure build-up,
Which can be handled by opening the top of the funnel routinely while mixing.
What can TLC be used for?
Assessing product purity.
