little things for unit 4 Flashcards
1
Q
what requirements must a substance meet to become a suitable primary standard
A
- high purity
- stable in air and in solution
- readily soluble in a solvent
- reasonably large relative atomic mass
2
Q
what are the three types of titrations
A
- acid base
- redox
- complexometric
3
Q
what is an acid base titration
A
titration reaction simply a neutralisation in which H+ ions are transferred from the acid to the base
4
Q
what is a redox titration
A
oxidising agent titrated against a reducing agent
5
Q
what is a complexometric titration
A
based on the formation of a complex
6
Q
what occurs in a back titration
A
- this involves adding a known but excess amonut of one standard reagent to a known mass of the substance being determined
- after reaction between the two is complete, the excess amount of standard reagent is determined by titration against a second standard reagent
7
Q
what is the purpose of the condensor in heating under reflux
A
prevent the escape of any volatile reactants or products from the apparatus
8
Q
what is recrystallisation
A
the simplest technique of purifying an organic solid
