Researching Chemistry pt 1 ✓

Titration is the accurate measurement of the volume of the standard to determine the concentration of the analyte

A standard solution is a solution of accurately known concentration

An analyte is a solution of an unknown concentration

An indicator is a substance that is used to determine the end point of a reaction (Phenolphthalien, Methyl orange)

Concordant results are results within 0.2cm3

A primary standard must have a: - High state of purity - Be stable when solid and in solution - Be soluble - Have a reasonabley high GFM (Sodium carbonate, Hydrated oxalic acid)

When they have a low GFM, are unstable as a solid or in solution, or absorb moisture from the air (Sodium hydroxide, NaOH)

A secondary standard is a standard that is prepared by titrating it against a primary standard

A complexometric titration is used to determine the concentration of metal ions in a solution

A complex is formed when a metal ion reacts with a ligand (EDTA)

A ligand is a molecule/negative ion with at least one non-bonding pairs of electrons that they donate to unfilled metal orbitals to form dative bonds

A dative bond is a covalent bond where one atom supplies both of the electrons

EDTA is a commonly used ligand. It wraps around the metal using 6 dative bonds (hexadentate). It is used to treat heavy metal poisoning or remove a metal from water

A metal ion indicator is an organic dye that changes colour when it binds to metal ions (Murexide (ln))

A back titration is a titration where a known quantity of one standard is added in excess to a known mass of analyte. Once the reaction is complete, the excess of the standard is determined by titration against a second standard

• When the analyte is insoluble/has low solubility • When the end-point is clearer for back titration than direct titration • If the reaction is slow between the standard and analyte