Chemistry paper 1 rp

Question 1

Write a method for a practical making a dry sample of a soluble salt.

Answer 1

1. Pour 40 cm of sulfuric acid into a beaker.
2. Set up bunsen burner on a heatproof mat with a tripod and gauze over it. Place beaker with acid in on the gauze and heat gently over a flame until almost boiling. TURN BUNSEN BURNER OFF
3. Place hot beaker on heatproof mat using tongs and add copper oxide one spoonful at a time, stirring using the glass rod as you add it. The mixture turns clear and blue
4. Folf and place a filter paper inside a funnel and filter the mixture into a conical flask.
5. Pour copper sulphate solution into evaporation basin and heat over a 250cm beaker acting as a water bath until half the solution has evaporated.
6. Use tongs to pour the copper sulphate solution into a crystallising dish and leave it in a warm place to finish crystallising.

Question 2

Write a method for a practical for determining the volumes of reacting solutions of a strong acid and a strong alkali by titration.

Answer 2

1. Set up equipment with a clamp stand holding the burette.
2. Find the approximate volume of acid required to neutralize the alkali. Pour 25 cm of alkali into a conical flask and then run the acid slowly into the alkali, always swirling. Do this until the solution turns from yellow-orange to red. Then record results in approx column.
3. Empty flask and wash with distilled water.
4. Measure out 25 cm of alkali and repeat the titration. Add the acid one drop at a time when nearing the expected end-point.
5. Repeat steps 2 and 3 until consistent results are obtained.
6. Calculate the mean volume of acid needed to neutralize the alkali.

Question 3

Write a method for a practical investigating what happens when aqueous solutions are electrolysed using inert electrodes. (electrolysis)

Answer 3

1. Measure copper chloride solution and pour into beaker.
2. Attach carbon rods to the edge of the beaker using crocodile clips.
3. Attach leads to rods and then to the direct current terminals of the power pack.
4. Turn on the power pack for 5 minutes maximum.
5. After 30 seconds, observe electrodes and record these observations. (do this every 30 seconds for 5 minutes)
6. After 5 minutes switch off the supply.
7. Clean equipment making sure there are no deposits left on electrodes.
8. Repeat steps 1-8 with different compounds.

Question 4

Write a method for a practical to separate colored substances.

Answer 4

1. Draw a pencil line 1.5cm from the bottom edge of the chromatography paper.