Chemical Analysis Flashcards
A pure substance means that
All the participles are the same
Fixed melting and boiling point
Contains only one substance
A mixture
Contains two or more substances which could be compounds or elements
The substances are not chemically joined together
Does not have a fixed melting point
Determining purity of a substance
A mixture does not have a sharp melting or boiling point. It changes state over a range of temperatures
Impurities tend to lower the melting point of a substance and raise its boiling point
Formulation
Is a mixture designed as a useful product
Mobile phase
Solvent in the liquid state
Stationary phase
Chromatography paper which is absorbent
Why do samples move up the filter paper at different rates
The distance the sample moves up the paper depends on what phase the sample favours
A sample that moves the most, favours the mobile phase so it is more soluble in the solvent and hence moves higher up
A sample that moves the least, favours the stationary phase as it doesn’t allow the solvent to move up the paper
Pure
Made from only one element or compound
Impure/ mixture
Two or more elements or compounds that are not chemically combined
Chlorine test
Damp blue litmus paper near gas
Bleached white if present
Oxygen test
Glowing splint
Oxygen present splint will relight
Hydrogen test
Lit splint
Squeaky pop if present
Carbon dioxide test
Bubble the gas through limewater
Limewater turns cloudy if present
