c12 chemical analysis

• pure substance


  a single element or compound with nothing else mixed in
• to measure the purity of a substance you use the melting and boiling point of a substance
• pure substances melt suddenly at sharp temperatures
• the melting and boiling point of pure elements are fixed
• if a substance melts over a range of temperatures it's considered impure
• the wider the melting point range is the less pure a substance is
• impurities lower the melting point of a substance
• salt is added to ice on roads to lower the melting point so it melts quicker
• if a substance distils suddenly it is considered pure
• if a substance distills over a range of temperatures, it is impure
• impurities increase the boiling point
• formulations


  many chemicals used for specific purposes are mixed with other things to produce a useful product
• RF value = distance travelled by ink/distance traveled by solvent
• chromatography can be used to separate dyes from a mixture
• in chromatography the most soluble component travels the furthest
• the RF value of specific substances can be used to identify the compound present in a mixture
• positively charges metal ions produce different coloured flames when they are heated using a bunsen burner
• when a metal ion is heated electrons are promoted to a higher shell and when they drop back down they produce a coloured light depending on the metal ion
• sodium gives a yellow flame
• calcium gives a red flame
• potassium gives a lilac flame
• lithium gives a red/crimson flame
• copper gives a green flame
• in flame emission spectroscopy the coloured light from a vaporised sample can be split to produce an emission spectrum
• the different lines in an emission spectrum look like a coloured barcode
• each metal ion produces a unique emission spectrum
• the metal ion present in an emission spectrum is identified by comparing it's spectrum with reference spectrums
• if two spectrums match they are from the same metal ion
• copper II produces blue precipitate
• Iron II produced green precipitate
• Iron III produces orange/ red precipitate
• negative ions produce different coloured precipitates depending on the metal in the ionic compound
• carbonates react with acid (H+) to give carbon dioxide and water
• sulphates reacted with HCl and then BaCl2 to give a white precipitate of barium sulphate
• halide ions reacted with silver nitrate and nitric acid produces different coloured precipitates
• chlorine has a white precipitate
• bromide has a cream precipitate
• iodine has a yellow precipitate
• limewater is calcium hydroxide
• low density poly(ethene) and high density poly(ethene) are made from the same monomer