core practicals Flashcards
investigating inks: simple distillation
A Set up your apparatus so that the ink is in a flask, and its vapours can be led away to be condensed. Diagram B shows some typical apparatus but yours may be different.
B Heat the flask of ink using a Bunsen burner, making sure the ink simmers gently and does not boil over into the delivery tube.
C Continue heating until you have collected a few cm³ of distillate (distilled solvent).
D Note the maximum temperature obtained.
investigating inks: paper chromatography
draw pencil line on chromatography paper about 2cm from bottom
add small ink dots on pencil line
add water to container to depth of 1cm
place paper so that paper is just about touching the water not so much that it covers the ink though
take paper out before water reaches the top of it
mark position of the solvent front using pencil then dry paper
measure distance travelled by water from pencil line and the distance travelled by each coloured substance calculate the Rf value for each coloured substance
preparing copper sulphate
measure 20cm^3 of dilute sulfuric acid using a measuring cylinder and pour it into a small conical flask then warm the acid in a water bath st at 50 degrees celcius, use a thermometer to measure the temp and add a little copper oxide powder to the acid and stir, if all the copper oxide reacts, and disappears, add a little more and stop when it is in excess and no longer reacts
filter the mixture and transfer the filtrate to an evap basin
heat the basin over a bunsen stop when crystals start to form then pour into a watch glass and leave for a few days to allow all the water to evaporate
investigating neutralisation
use a measuring cylinder to add 50cm^3 of dilute hydrochloric acid to a beaker
estimate and record the pH of the contents of the beaker by putting a piece of universal indicator paper onto a white tile
dip the end of the glass rod into the liquid then tap onto the universal indicator paper then wait 30 seconds and match the colour with the colour on a pH colour chart
measure out 0.3grams of calcium hydroxide powder onto a piece of paper or a weighing boat
add the calcium hydroxide powder to a beaker and stir then estimate and record the pH of the mixture
repeat the pH estimation and measuring of the calcium hydroxide about 7 times so that you add a total of 2.4 grams of calcium hydroxide powder to the acid
then finally plot a graph with ph on the vertical axis and mass of calcium hydroxide on the horizontal axis
electrolysis of copper sulphate solution
select 2 pieces of copper foil. label one anode and the other cathode and measure and record there masses then set up an electrolysis circuit with wires, circuit, and copper electrodes in a beaker with copper sulphate solution
turn on power to about 0.2Amps and record the current and adjust the variable resistor to keep it constant, leave the power for 20 minutes
turn off the power and remove the electrodes from the beaker and gently wash the electrodes with distilled water then dip them in propanone and then lift the electrodes out and gently shake off the propanone lift the electrodes and allow the propanone to evaporate
measure and record masses of dry electrodes
repeat using currents 0.3 0.4 and 0.5
acid-alkali titration
Rinse the burette with hydrochloric acid then fill the burette with the acid and making sure the jet below the tap is also full then record the initial volume of the acid in the burette, rinse a pipette with sodium hydroxide solution and then full the pipette to 20cm^3 mark and empty the solution into a conical flask
add a few drops of methyl orange indicator to the flask and place the flask on a white tile under the burette
then add the acid to the sodium hydroxide solution while swirling the flask
when the indicator starts to change colour rinse the tip of the burette and the sides of the flask with a small amount of distilled water from a wash bottle to ensure that all the acid id in the mixture then add acid drop by drop until the end point is reached
record the final volume of the acid in the burette
repeat the experiment apart from the initial rinsing of the burette and pipette, until concordant results are obtained.
investigating reaction rates
set up the apparatus with a conical flask with a bung to a delivery tube which goes into a water trough with a measure cylinder facing down into the water and the delivery tub going into the measuring cylinder
measure 40cm^3 of dilute hydrochloric acid into a conical flask
add 5cm^3 of small marble chips to the flask
immediately stopper the flask and start the stop clock
note the total volume of the gas produced after every 30 seconds until the reaction has finished and repeat the experiment using 5g of larger marble chips
investigating reaction rates: observing colour change
place 50cm^3 of sodium thiosulfate solution into a 300cm^3 conical flask
measure out 5cm^3 of dilute hydrochloric acid in a test tube
clamp the conical flask in place in a water bath at a certain temp then place the test tube in a rack in the same water bath and record this temperature
after5 minutes remove the flask and place it on a piece of white paper marked with a cross
add the acid to the thiosulphate and start the stop clock
combustion of alcohols
measure the mass of the alcohol burner and the cap record the mass and name of the alcohol
place the alcohol burner in the centre of a heat resistant mat
the use a measuring cylinder add 100cm^3 of cold water to the conical flask
measure and record the initial temperature of the water and clamp the flask above the alcohol burner
light the wick of the burner and measure and record the final temperature of the water
measure the mass of the alcohol burner and the cap again and record the mass
calculate the mass of the alcohol burned and cap again and record the mass
calculate the mass of the alcohol burned to produce a 1 degree Celsius rise in temperature
and repeat all of this using fresh water
identifying ions: flame test for metal cations
A Light a Bunsen burner and open the air hole to give a hot blue flame.
B Pick up a small sample of a solid salt using a clean wire loop or a damp wooden splint.
C Hold the sample in the edge of the flame.
D Observe and record the flame colour.
identifying ions: precipitate test for metal cations
E Dissolve a little solid salt in a test tube using distilled water.
F Add a few drops of dilute sodium hydroxide solution, one drop at a time.
G Record the colour of any precipitate formed.
H If a white precipitate forms, add excess dilute sodium hydroxide solution to see if it will disappear to leave a clear solution.
identifying ions: hydroxide test for metal cations ions
I Dissolve a little solid salt in a test tube using distilled water.
J Add dilute sodium hydroxide solution and then warm gently.
K Remove from the flame. Hold a piece of damp red litmus paper near the mouth of the test tube. Record what happens to its colour.
identifying ions: testing for ammonium ions
L Put a little solid salt in a test tube and add a few drops of dilute acid.
M Record whether any effervescence (bubbling) occurs.
N Use limewater to check that any bubbles contain carbon dioxide.
identifying ions: testing for carbonate ions
L Put a little solid salt in a test tube and add a few drops of dilute acid.
M Record whether any effervescence (bubbling) occurs.
N Use limewater to check that any bubbles contain carbon dioxide.
identifying ions: testing for sulphate ions
O Dissolve a little solid salt in a test tube using distilled water.
P Add a few drops of dilute hydrochloric acid, then a few drops of barium chloride solution. Record whether a white precipitate forms.
identifying ions: testing for halide ions
dissolve a little solid salt in a test tube using distilled water then add a few drops of silver nitrate solution and record the colour of the precipitate
