Changes

*Looking at its [[property|properties]] such as the [[Melting Point|melting point]] and [[Boiling Point|boiling point]]. If these are spread over a range of [[temperature]]s or different from the known values for the [[pure]] [[substance]] then the sample is not [[pure]]. For example to test if a sample of [[Water]] is [[pure]] it can be [[melting|melted]] from [[Ice]] and [[boiling|boiled]] from [[liquid]] [[Water]]. If the [[Melting Point|melting point]] is exactly 0°C and the [[Boiling Point|boiling point]] is exactly 100°C, then the [[Water]] is [[pure]].

*Using [[Chromatography]] to observe if a [[soluble]] [[solid]] is a [[mixture]] which [[Separating Mixtures|separate]]s on piece of [[Chromatography]] paper (there is more than one dot on the [[Chromatogram]]). For example a sample of coloured ink can be placed on some [[chromatography]] paper. Using a suitable [[solvent]] the [[solute]]s within the ink will move along the [[chromatography]] paper. If there is more than one [[solute]] then ink will split into more than one dot on the [[Chromatogram]].