Volumetric Analysis Flashcards
what is a standard solution?
a solution of accurately known concentration
how is a standard solution prepared?
accurately weigh a primary standard
dissolve in a small volume of deionised water
transfer to a volumetric flask with rinsings
make up to the graduation mark, stopper and invert
how is a standard solution prepared by dilution?
pipette a volume of standard solution into a volumetric flask
make up to the graduation mark with water
stopper and invert
what are the properties of a good primary standard?
high purity
stable as solid and in solution
soluble
reasonably high GFM
why is sodium hydroxide not a primary standard?
low GFM
absorbs moisture (unstable as solid)
unstable in solution
what must be done before using NaOH in volumetric analysis?
it must be standardised
what are the 4 types of titrations?
acid-base
redox
complexometric
back titration
what is a back titration?
a titration used to determine the amount of a substance by reacting it with excess known reactant then titration the leftover reactant
when are back titrations used?
when the substance is a solid
when the substance is insoluble
what is the formula for dilution factor?
final / initial
how do you calculate final concentration after dilution?
initial concentration / dilution factor
