practicals Flashcards
1-making salts
describe process
-measure 15cm3 of dilute acid into beaker and heat gently using Bunsen Burner
-add insoluble base until in excess
-filter using filter paper and funnel to remove excess
-pour solution in evaporating basin and heat gently until crystallisation point
-let crystals cool, then pat dry with filter paper
2-neutralisation
-use pipette to measure 25cm3 of alkali into flask
-put white tile under flask
-fill burette with acid and record initial reading
-add few drops of indicator (phenolpthalein) to flask
-add acid to flask while swirling
-add acid drop-wise near end point until colour change
-record final reading on burette- this is the volume used to neutralise the alkali
-repeat until you have concordant results
3-electrolysis
-add 50cm3 aqueous solution to beaker
-add lid and insert electrodes through holes-make sure they don’t touch
-attach crocodile clips to electrode and connect rods to DC supply and set it to 4V
-use forceps to hold litmus paper near positive electrode
-turn supply off and observe negative electrode
3- electrolysis
what happens at the positive electrode with copper chloride solution
-chlorine formed
-state is a gas
3- electrolysis
what happens at the negative electrode with copper chloride solution
-solid brown/red coating on rod
-copper formed
-state is solid
3- electrolysis
what happens at the positive electrode with sodium chloride solution
-bubbling
-litmus bleaches white
-chlorine formed
-state is gas
3- electrolysis
what happens at the negative electrode with sodium chloride solution
hydrogen formed
-state is gas
4-temperature changes
describe process
-measure 25cm3 of HCl into polystyrene cup and put cup into a beaker
-record temperature of HCl
-measure 5cm3 sodium hydroxide and add to cup
-put lid on cup and stir solution with thermometer through hole in the lid
-record temperature when it stops changing and becomes constant
-repeat, adding further 5cm3 of sodium hydroxide until 40cm3
-calculate maximum mean temperature reached for each sodium hydroxide volume
5-rate of reaction
describe process-vol of gas produced
-measure 50cm3 of 1.0M of HCl into flask
-add 3cm strip of Mg ribbon to flask and place bung into flask. Start stopwatch
-record volume of hydrogen gas every 10 secs. Stop when no more gas comes out
-repeat with 1.5M HCl
5-rate of reaction
describe process- colour change
-measure 10cm3 solution into flask
-dilute it by adding 40cm3 water
-put flask on black cross
-measure 10cm3 dilute HCl and add to flask
-swirl flask, start stopwatch
-look down through top of flask. Stop stopwatch when cross is no longer visible. Record time taken
-repeat with different volumes of solution and water
6-chromatography
describe process
-draw horizontal line in pencil near bottom of chromatography paper
-use capillary tube to put a spot of each sample on the line
-pour water into beaker so the paper just touches the water and suspend the paper
-wait for solvent to travel 3/4 up the paper
-remove paper, draw another line next to where the solvent travelled up to-solvent front
-let paper dry
-calculate Rf values for each spot- distance travelled by solvent/solvent front
7-identifying ions
describe process
-pour 1cm3 of each solution into 5 test tubes
-clean wire by dipping it in dilute HCl
-dip wire into solution and hold it in a blue flame
-record colour of the flame
-repeat with other solutions. Clean wire after each test
7-identifying ions
what are the colours for each solution flame (5)
-lithium-red
-potassium-lilac
-copper-green
sodium-yellow
-calcium-orange red
7-identifying ions
carbonate ions test results
-bubbles produced
-limewater cloudy
7-identifying ions
sulphate ions test results
-white precipitate formed
