-
using sodium carbonate to standardise HCL
- methyl orange indicator.. yellow -> faint pink
- indicators are slighty acidic so dont use too much
-
primary standard
sodium carbonate
-
sodium hydroxide
causes burns
-
sodium hydroxide and HCL
methyl orange, yellow->red
-
% ethanoic acid in vinegar
- phenolphthalein... pink ->colourless
- (weak acid strong base)
-
% water crystallisation in hydrated sodium carbonate
methyl orange... yellow -> pink
-
halogens
acts as oxidising agents because high electronegativity values
-
ammonium iron(II)sulfate and KMnO4
- >add dilute sulphuric acid at start to prevent hydrolis (Fe2+ -> Fe3+)
- >add before titration to provide H+ ions, stop MnO2 forming, dark brown ppt
- >no indicator needed.. faint perm. pink
- >read from top.. intense colour
-
amount of iron in tablet
- iron(II)sulfate and KMnO4
- add dilute sulphuric acid
- acts as own indicator
- stains glassware
-
sodium thiosulphate and iodine
- add dilute sulphuric acid.. liberates iodine (brownish/red)
- titrate until pale yellow.. add starch indicator.. blue/black.. titrate until colourless
-
iodine
not primary standard... vapourises at room temp.. polar
-
%(w/v) of sodium hypochlorite in household bleach
- >dilute bleach.. otherwise large amount of thiosulphate would be needed
- >bleach in conical flask.. add sulphuric acid and potassium iodine
- >dilute sulphuric acid.. liberates iodine (reddish/brown colour)
- >titrate.. pale yellow.. starch indicator.. blue/black.. colourless
-
using pipette
- 1.rinse with deionised water,
- 2.rinse with liquid thats to go in it,
- 3.use pipette filler, measure 25cm3, 4.bottom of meniscus on line at eye level,
- 5.hold upright and allow it to drain,
- 6.touch tip of pipette on inside of conical flask
-
diluting
- 1.pipette in solution
- 2.add deionised water until below mark
- 3.level surface.. get down to eye level.. use wash bottle of deionised water and fill until bottom of meniscus at mark
- 4.stopper and invert 20 times
- 5.label
-
using a burette
- 1.wash with deionised water
- 2.rinse with solution
- 3.allow rinsed solution to run through
- 4.using funnel fill burette with solution to above the zero mark.. remove funnel
- 5.open tap and allow area below tap to fill
- 6.close tap when bottom of meniscus at zero
- 7.make sure it clamped safely and upright
-
conical flask
- 1. shaped for convience of stirring and shaking.. no spilling
- 2. sides can be washed down with deionised water at any time
- 3.this will dilute solution but not change the number of moles of solution measure in it
|
|
