CORE PRACTICALS chemistry

CP 1- To investigate the composition of inks using simple distillation- step 1

Add a small volume of ink to a flask and connect the flask to a condenser. Connect the condenser to a tap and place a beaker at the end of the opening.

CP 1- To investigate the composition of inks using simple distillation- step 2

Using a Bunsen burner, heat the flask slowly so that the ink simmers.

CP 1- To investigate the composition of inks using simple distillation- step 3

Collect a sample of the distilled solvent. Turn the Bunsen burner off when finished

CP 1- To investigate the composition of inks using paper chromatography- step 1

Use a pencil to draw a line across the chromatography paper.

CP 1- To investigate the composition of inks using paper chromatography- step 2

Use the pipette to add small dots of different inks to the line on the chromatography paper.

CP 1- To investigate the composition of inks using paper chromatography- step 3

Place the paper in a beaker containing 1 cm3 of solvent and leave the solvent until it has moved 2/3 of the way up the paper.

CP 1- To investigate the composition of inks using paper chromatography- step 4

Remove the chromatogram from the solvent. Mark where the solvent reached by drawing a horizontal line across the chromatography paper at this point.

CP 1- To investigate the composition of inks using paper chromatography- step 5

Leave the chromatography paper until the solvent has dried.

CP 1- To investigate the composition of inks using paper chromatography- step 6

Measure the distance travelled by the solvent front and the spots from the pencil line.

CP 2- Investigating pH (neutralisation)- step 1

Using the measuring cylinder or volumetric pipette, add 25 cm3 of dilute hydrochloric acid to a beaker.

CP 2- Investigating pH (neutralisation)- step 2

Add a few drops of universal indicator. Compare the initial colour of the solution to a pH colour chart and record the pH.

CP 2- Investigating pH (neutralisation)- step 3

Add calcium hydroxide or calcium oxide to the beaker, stirring and recording the pH between additions.

CP 2- Investigating pH (neutralisation)- step 4

Stop adding calcium hydroxide/calcium oxide when the pH remains constant.

CP 3- Investigate the preparation of pure, dry hydrated copper sulfate crystals starting from copper oxide including the use of a water bath- step 1

Using a measuring cylinder, measure 25 cm3 of sulfuric acid into a beaker. Place the beaker in a water bath to warm the sulfuric acid.

CP 3- Investigate the preparation of pure, dry hydrated copper sulfate crystals starting from copper oxide including the use of a water bath- step 2

Add copper oxide to the acid, 1 spatula at a time, stirring with a glass rod between additions. Continue adding copper oxide until it is in excess and the solid doesn't disappear when stirred.

CP 3- Investigate the preparation of pure, dry hydrated copper sulfate crystals starting from copper oxide including the use of a water bath- step 3

Put a piece of filter paper in a funnel over a beaker. Pour the solution through the funnel to remove excess copper oxide.

CP 3- Investigate the preparation of pure, dry hydrated copper sulfate crystals starting from copper oxide including the use of a water bath- step 4

Pour the filtrate into an evaporating basin. Place on a tripod with gauze and heat with a bunsen burner to start evaporation.

CP 3- Investigate the preparation of pure, dry hydrated copper sulfate crystals starting from copper oxide including the use of a water bath- step 5

When almost all the water has evaporated, turn off the heat and leave to dry. Blue copper sulfate crystals will remain in the basin.

CP 4- Investigate the electrolysis of copper sulfate solution with inert electrodes- step 1

Pour copper sulfate solution into a beaker so that it is half full.

CP 4- Investigate the electrolysis of copper sulfate solution with inert electrodes- step 2

Place two inert graphite electrodes into the beaker and attach to a power supply using crocodile clips and wires.

CP 4- Investigate the electrolysis of copper sulfate solution with inert electrodes- step 3

Fill 2 test tubes with copper sulfate solution and place over each electrode

CP 4- Investigate the electrolysis of copper sulfate solution with inert electrodes- step 4

Turn on the power and record any observations.

CP 4- Investigate the electrolysis of copper sulfate solution with inert electrodes- step 5

Use a glowing splint to test any gas that has collected in the test tubes. Record any observations

CP 4- Investigate the electrolysis of copper sulfate solution with copper electrodes- step 1

Measure the mass of a copper electrode and attach to the negative terminal of the power supply. Repeat with a second copper electrode, attaching it to the positive terminal. Record the masses.

CP 4- Investigate the electrolysis of copper sulfate solution with copper electrodes- step 2

Pour copper sulfate solution into a beaker. Place the copper electrodes in the beaker

CP 4- Investigate the electrolysis of copper sulfate solution with copper electrodes- step 3

Turn on the power supply, making sure the electrodes don't touch. Turn off the power after about 20 minutes.

CP 4- Investigate the electrolysis of copper sulfate solution with copper electrodes- step 4

Remove each electrode, washing in distilled water then propanone. Leave the liquid to evaporate from the electrodes before measuring the mass of each one. Record the results, ensuring you know which electrode is which.

CP 4- Investigate the electrolysis of copper sulfate solution with copper electrodes- step 5

Repeat steps 1-4 with fresh electrodes and copper sulfate solution. Change the current using the variable resistor.

CP 5- Carry out an accurate acid-alkali titration, using burette, pipette and a suitable indicator- step 1

Add exactly 25 cm3 of sodium hydroxide to a conical flask using a pipette and pipette filler. Add a few drops of phenolphthalein indicator to the conical flask then place the conical flask on a white tile.

CP 5- Carry out an accurate acid-alkali titration, using burette, pipette and a suitable indicator- step 2

Setup the burette in the clamp and stand. Close the tap and use a funnel to pour about 10 cm3 of hydrochloric acid into the burette.

CP 5- Carry out an accurate acid-alkali titration, using burette, pipette and a suitable indicator- step 3

Place a beaker under the burette and open the tap, allowing the tip of the burette to fill with acid and displace any air bubbles.

CP 5- Carry out an accurate acid-alkali titration, using burette, pipette and a suitable indicator- step 4

Close the tap before the burette empties then use a funnel to fill the burette with acid. Record the initial burette reading to the nearest 0.05 cm3 .

CP 5- Carry out an accurate acid-alkali titration, using burette, pipette and a suitable indicator- step 5

Place the burette above the conical flask. Carry out a rough trial titration, adding the acid 1-2 cm3 at a time, swirling the conical flask constantly.

CP 5- Carry out an accurate acid-alkali titration, using burette, pipette and a suitable indicator- step 6

Close the burette tap as soon as the solution decolourises. Record the final burette volume and calculate the volume of acid that has been added from the burette.

CP 5- Carry out an accurate acid-alkali titration, using burette, pipette and a suitable indicator- step 7

Rinse the conical flask with deionised water then add 25 cm3 of sodium hydroxide. Refill the burette if necessary and record the initial volume of acid in the burette.

CP 5- Carry out an accurate acid-alkali titration, using burette, pipette and a suitable indicator- step 8

Using the rough titre as guidance, add the acid to the conical flask until within about 4 cm3 of the rough titre volume. Add the acid drop by drop after this, swirling constantly until the endpoint is reached. Record the final burette reading and use this value to calculate the titre volume.

CP 5- Carry out an accurate acid-alkali titration, using burette, pipette and a suitable indicator- step 9

Repeat steps 7 and 8 until concordant titres are obtained

CP 5- Carry out an accurate acid-alkali titration, using burette, pipette and a suitable indicator- step 10

Use the concordant results to calculate the mean titre.

CP 6- Investigate the effects of changing the conditions of a reaction on the rates of chemical reactions- step 1

Add 50 cm3 of dilute hydrochloric acid to the conical flask.

CP 6- Investigate the effects of changing the conditions of a reaction on the rates of chemical reactions- step 2

Add 0.4 g of marble chips to the conical flask. Immediately attach the bung - this should be connected to the gas collection vessel via the delivery tube. Start the timer.

CP 6- Investigate the effects of changing the conditions of a reaction on the rates of chemical reactions- step 3

For every 10 cm3 of gas produced, record the time in a results table.

CP 6- Investigate the effects of changing the conditions of a reaction on the rates of chemical reactions- step 4

Repeat steps 1-4 for different concentrations of acid.

CP 6- Investigate the effects of changing the conditions of a reaction on the rates of chemical reactions- step 5

The experiment may be repeated, changing the size of the marble chips instead of the concentration of acid. The marble chips can be made smaller by crushing them in a pestle and mortar. For this to be a fair test, the concentration and volume of HCl and the mass of marble chips must be controlled.

CP 7- Identify the ions in unknown salts, using the tests for the specified cations and anions- flame test

1. Clean a wire loop by dipping it in HCl then holding it in a blue flame until it burns without altering the colour of the flame.

2. Dip the clean wire loop into the unknown salt and then hold the loop in the blue flame of a bunsen burner. Record the colour.

3. Repeat for the other unknown samples.

CP 7- Identify the ions in unknown salts, using the tests for the specified cations and anions- Hydroxide precipitates test

1. Place a little of the unknown solution in a test tube and add a few drops of dilute sodium hydroxide solution. Record any observations.

2. If a white precipitate forms, add an excess of sodium hydroxide solution and record any observations

CP 7- Identify the ions in unknown salts, using the tests for the specified cations and anions- Test for ammonium ions

1. Place a little of the unknown solution in a test tube and add a few drops of dilute sodium hydroxide solution. Warm the solution gently with a bunsen burner, holding the test tube with tongs.

2. Place a piece of damp red litmus paper over the end of the test tube and record any observations.

CP 7- Identify the ions in unknown salts, using the tests for the specified cations and anions- Test for carbonate ions

1. Add a few drops of dilute hydrochloric acid to a boiling tube containing the unknown solution.

2. Place a bung and delivery tube onto the boiling tube and place the other end of the delivery tube into a test tube of limewater. Record any observations

CP 7- Identify the ions in unknown salts, using the tests for the specified cations and anions- Test for sulfate ions

1. Add a few drops of hydrochloric acid to a test tube of the unknown substance followed by a few drops of barium chloride. Record any observations.

CP 7- Identify the ions in unknown salts, using the tests for the specified cations and anions- Test for hailde ions

1. Add a few drops of nitric acid to the unknown solution followed by a few drops of silver nitrate. Record any observations

CP 8- Investigate the temperature rise produced in a known mass of water by the combustion of the alcohols ethanol, propanol, butanol and pentanol- step 1

Place a copper can in a clamp stand. Adjust the height so that the copper can will sit just above the flame of the spirit burner.

CP 8- Investigate the temperature rise produced in a known mass of water by the combustion of the alcohols ethanol, propanol, butanol and pentanol- step 2

Using a measuring cylinder, pour 100 cm3 of water into the copper can. Record the initial temperature.

CP 8- Investigate the temperature rise produced in a known mass of water by the combustion of the alcohols ethanol, propanol, butanol and pentanol- step 3

Measure the initial mass of the spirit burner and lid containing the first alcohol.

CP 8- Investigate the temperature rise produced in a known mass of water by the combustion of the alcohols ethanol, propanol, butanol and pentanol- step 4

Place the spirit burner under the copper can. Take off the lid and light with a wooden splint.

CP 8- Investigate the temperature rise produced in a known mass of water by the combustion of the alcohols ethanol, propanol, butanol and pentanol- step 5

Replace the lid of the spirit burner when the temperature has risen about 20°C. Make sure to stir the water constantly. Record the final temperature.

CP 8- Investigate the temperature rise produced in a known mass of water by the combustion of the alcohols ethanol, propanol, butanol and pentanol- step 6

Measure the final mass if the spirit burner and lid.

CP 8- Investigate the temperature rise produced in a known mass of water by the combustion of the alcohols ethanol, propanol, butanol and pentanol- step 7

Repeat steps 2 to 6 with the other alcohols. Make sure fresh water is used in each experiment.