chemical analysis

test for positive ions

a wire loop should be dipped in concentrated hydrochloric acid and heated to clean it. then dip it in the ion to be tested. hold the wire loop in the roaring blue flame. the colour the Bunsen flame to identify the metal ion in the compound. however if the sample used has a mixture of metal ions, then some flame colours can be masked. for example, the intense yellow colour of sodium ions can dominate other colours.

lithium - crimson

sodium - yellow

potassium - lilac

calcium - orange/red

copper - green

sodium hydroxide test

add sodium hydroxide into the ion and a precipitate will be formed

Cu (two plus) - blue

Fe (two plus) - green

Fe (three plus) - brown precipitate

if precipitate is white, add sodium hydroxide in excess. if it then goes clear, it is Al (three plus). if it stays cloudy, the flame test is required to figure out if it is calcium (two plus) or magnesium. if it is magnesium there will be no colour.

cation are positive ions and anions are negative ions

to test for a carbonate, you mix is with hydrochloric acid in a test tube, and put a bung with a tube going into another test tube with limewater in. if a white precipitate is formed, it is a carbonate

to test for a halide, you add nitric acid and silver nitrate to the halide. a precipitate will be formed.

white precipitate - chlorine

yellow precipitate - iodine

cream precipitate - bromine

to test for sulfates, you mix hydrochlrric acid with barium chloride. if a white precipitate is formed, it is a sulfate.

moles = mass/RFM

percentage yeild = actual yield/expected yield +ions

percentage atom economy = required product/ all RFM of reactants x100

concentration (g/dm cubed) = amount of substance/dm cubed

moles of gas = volume/24