Practicals

Question 1

Rate of reaction(1)

Answer 1

1. Measure 10 cm3 sodium thiosulfate solution into the conical flask
2. Measure 40 cm3 water and add it to the conical flask
3. Put the conical flask on the black cross marked on a white tile -
4. Measure 10 cm3 of dilute HCL
5. Add the acid to the flask. At the same time, swirl the flask gently and start the stopwatch
6. Look down through the top of the flask. Stop the clock when you can no longer see the cross and record the time taken
7. Repeat steps 1‒6 four times, using different volumes of sodium
   thiosulfate and water. This will change the concentration of sodium thiosulfate
8. Repeat steps 1-7 for a mean for the rate of reaction using diff concs

Question 2

Rate of reaction (2)

Answer 2

1. Measure 50 cm3
   of 1.0 M hydrochloric acid using one of the measuring cylinders. Pour
   the acid into the 100 cm3
   conical flask.
2. Set up the gas syringe to be connected to the bung which is connected to the beaker by a delivery tube
3. Add a 3 cm strip of magnesium ribbon to the flask and quickly place the bung back into the flask. At the same time, start the stopwatch.
4. Record the 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 hydrochloric acid
6. Plot a graph of ‘volume of gas produced’ (y-axis) against ‘time’ (x-axis) . Draw two
   curves, one for each concentration of acid.

Question 3

Chromatography

Answer 3

-Pencil baseline with a ruler and put drop of the in on the baseline on chromatography paper
-fill beaker with solvent - water or ethanol up shallow - no more than 4 cm
-Use a glass capillary tube to put a small spot of each colouring on the pencil spots.
-suspend chromatography paper in solvent ,so the bottom edge is dipped in solvent just under baseline and and hold it upright using tape or a stick
-lid optional to stop solvent evaporating
-leave to dry

Question 4

water purification(1)

Answer 4

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

Question 5

Water purification (2)

Answer 5

1. Place the water sample in a conical flask and set up the conical flask on a Wire gauze on a tripod above a bunsen burner . Add a bung to the conical flask and add a delivery tube going to a test tube in a beaker full of ice water , this test tube should be held up by a clamp
2. Heat the water gently using a Bunsen burner until it boils. Then reduce the heat so the water boils gently
3. Collect around 1 cm depth of water in the cooled test tube, then stop heating
4. Analyse the water you have distilled with cobalt chloride paper