C3-analysis and synthesis

tests for positive ions

• some positive ions can be identified by doing a flame test of sodium hydroxide solution
• LITHIUM (Li)= CRIMSON
• SODIUM(Na)=YELLOW
• POTASSIUM(K)=LILAC
• CALCIUM(Ca2+)=RED
• BARIUM(Ba2+)=GREEN
• LITTLE SLIMEY POOS CRACK BUMHOLES/CREEPY YELLOW LEMONS READ GRAZIA
• metals that have ions with a 2+ or 3+ are insoluble in water, a precipitate is formed
• aluminium, calcium and magnesium form white precipitate
• when excess sodium hydroxide solution is added to the precipiate of aluminium hydoxide dissolves
• copper 2 hydroxide = blue
• iron 2 hydroxide= green
• iron 3 hydroxide= brown

tests for negative ions

• there are three tests carbonate, halide and sulfate
• to see if a substance contains carbonate you add dilute hydrochloric acid to substance to see if it fizzes if it does and the gas produced turns limewater milky the substance contains carbonate ions
• to see if a substance contains halide ions you add dilute nitric acid and then silver nitrate solution chloride ions give you white precipitate, bromide ions give you cream precipitate and iodide ions give a yellow precipitate
• to test for sulfate ions add hydrochloric acid and then barium chloride solution, if a white precipitate forms sulfate ions are present

titrations

• when solutions of an acid and an alkali form a salt and a water neutralisation takes place
• volumes of solutions that react can be found by titration
• titration- use a pipette to measure accuratley the vol of alkali put into conical flask, indicator is added to…