P2- Required Practicals

Question 1

1a) Rate of reaction (using volume of gas produced)

Answer 1

1. Measure 50 cm3 of 1.0 M HCl using one of the measuring cylinders. Pour it into 100 cm3 conical flask
2. Set up apparatus
3. Add 3 cm strip of magnesium ribbon to flask and quickly place bung back into the flask and start the stopwatch.
4. Record volume of hydrogen gas given off every 10 seconds. Stop when no more gas is given off
5. Repeat steps 1-4 using 1.5 M HCl
6. Plot a graph of ‘volume of gas produced’ (y-axis) against ‘time’ (x-axis)

Question 2

1b) Rate of reaction (using colour change)

Answer 2

1. Measure 10 cm3 sodium thiosulfate solution into conical flask
2. Dilute solution, adding 40 cm3 water into conical flask making the concentration 8 g/cm3
3. Put the conical flask on the black cross
4. Measure 10 cm3 of dilute HCl
5. Add acid to flask, swirl the flask gently and start the stopwatch
6. Look down through top of flask. Stop clock when you no longer see the cross and record time taken
7. Repeat steps 1‒6 , using different volumes of sodium thiosulfate and water - 20 cm3 sodium thiosulphate solution + 30 cm3 water
8. Repeat steps 1-7 twice more
9. Calculate mean time for each sodium thiosulfate concentration

Question 3

2) Chromatography

Answer 3

1. Draw horizontal pencil line 2cm from short edge of C paper
2. Mark pencil spots equal intervals across the line
3. Use glass capillary tube to put small spot of each colouring on pencil spots
4. pour 1cm3 of water into the beaker
5. Suspend paper in the beaker so bottom edge of the paper dips in the water
6. Wait for water solvent to travel 3/4 up the paper
7. Remove paper and draw another line on dry part of paper right next to wet edge (the solvent front)
8. Hang paper up to dry thoroughly
9. Calculate Rf values for each spot

Question 4

3a) Identifying ions (Flame tests)

Answer 4

1.Pour 1 cm3 of each known chloride solution into 5 test tubes
2.Clean nichrome wire by dipping it in dilute HCl
3.Dip nichrome wire into solution, hold tip in blue bunsen flame
4.Record the colour of the flame
5.Repeat for other solutions, make sure to clean the wire after each test
6.Pour 1 cm3 of unknown salt solution into test tube
7.Dip nichrome wire into solution, hold tip in blue bunsen flame
8. Record the colour of the flame, you should be able to compare results with the known chloride with the matching colour flame.

Question 5

3b) Identifying ions (Carbonate ion test)

Answer 5

1.Place 2 cm3 of limewater in a clean test tube
2. Add a little dilute HCl to the unknown solution
3. If bubbles, transfer gas produced to the limewater using a delivery tube
4. Repeat process for the known sodium solutions to identify carbonates ions
Results: Bubbles produced and limewater goes cloudy if present

Question 6

3c) Identifying ions (Sulphate ion test)

Answer 6

1. Add 10 drops of dilute HCl to unknown solution in a test tube
2. Add 2 cm3 barium chloride solution
3. Pour 1 cm3 of known sodium solutions into separate test tubes
4. Add 5 drops of dilute HCl and then 2 cm3 of barium chloride
   Results: White precipitate formed if present

Question 7

3d) Identifying ions (Haide ion test)

Answer 7

1.Add 10 drops of dilute nitric acid to unknown solution in test tube
2. Add 1 cm3 silver nitrate solution to test tube with unknown solution
3. Pour 1cm3 of known sodium solutions into separate test tubes
4. Repeat steps 1 and 2 for other solutions
5. Record colour of precipitate formed in each test tube
Results: Chloride – white precipitate produced
- Bromide – cream precipitate produced
- Iodide – yellow precipitate produced

Question 8

4a) Water purification (Analysing a sample of water)

Answer 8

1. Use universal indicator to test pH of the water
2. Measure and record mass of an empty evaporating basin
3. Pour 10 cm3 water into evaporating basin and evaporate using a bunsen burner until most of the water has evaporated
4. Once evaporating basin is cool, reweigh/record change in mass
5. Calculate the mass of dissolved solids in the water

Question 9

4b) Water purification (Purifying a sample of water by distillation)

Answer 9

1. Place water sample in conical flask and set up apparatus for distillation
2. Heat water gently using bunsen burner until it boils. Reduce heat so water boils gently
3. Collect 1 cm depth of water in cooled test tube, then turn the bunsen burner off
4. Analyse water you have distilled with cobalt chloride paper