Chemistry ( Core Practical's & Processes ) Flashcards
States of Matter: Drinking Water
Explain the process of obtaining Drinking Water.
1. Large objects are removed by screening using grids
2. Coarse filter bed made from clean sand and gravel removes larger insoluble grit particles
3. Aluminium sulfate is added to clump smaller insoluble particles together, which then settle to the bottom in a sedimentation tank.
4. A fine filter bed removes very small insoluble particles.
5. Chlorine gas is added to kill harmful microorganisms.
Core Practical 1: Investing Inks ~ Simple Distillation
Describe the process of investigating inks through Simple Distillation.
Aims ~ To investigate the composition of inks using simple distillation and chromatography.
1. Add a small volume of ink to a flask. Connect the flask to the fractionating column and secure it with a stand, boss and clamp.
2. Attach a condenser to the top of the fractionating column, connect it to a cold water tap and sink, and secure it over a beaker.
3. Heat the flask using a Bunsen burner, reducing the flame as necessary to achieve gentle simmering.
4. Collect a small sample of the distilled solvent then turn the Bunsen burner off.
Core Practical 1.5: Investing Inks ~ Paper Chromatography
Describe the process of investigating inks through Paper Chromatography. ( Include Risks )
Method:
1. Draw a pencil line across the chromatography paper, 1-2 cm from the bottom
2. Use a pipette to add small spots of each ink to the line on the paper.
3. Place the paper into a container with a suitable solvent in the bottom.
4. Allow the solvent to move through the paper, but remove the chromatogram before it reaches the top.
Risks:
- Hot Apparatus: Cool appartus before touching it.
- Bunsen Burner Flame: Keep hair & clothes tucked in.
Core Practical 2: Investigating neutralisation
A) Describe how you would investigate neutralisation.
B) How could you make your results more accurate?
Aims ~ To investigate the change in pH when adding powdered calcium hydroxide to a fixed volume of dilute hydrochloric acid.
Method:
1. Use a measuring cylinder to add dilute hydrochloric acid to a beaker.
2. Dip a clean glass rod into the beaker. Use it to transfer a drop of liquid to a piece of UI paper on a white tile.
3. Wait 30 seconds, then match the colour to a pH colour chart. Record the estimated pH.
4. Add a level spatula of calcium hydroxide powder to the beaker.
5. Stir thoroughly, then estimate and record the pH of the mixture.
- Repeat steps 3 and 4 until there are no more changes in pH.
B) This could be done by;
- Measuring the mass of calcium hydroxide powder using a balance.
- Use a pH probe and meter to measure the pH rather than estimating with UI.
UI - Universal Indicator
Core Practical 3: Preparing Copper Sulphate
Describe the process of preparing Copper Sulphate.
Aim ~ To investigate the preparation of pure, dry hydrated copper sulfate crystals starting from copper oxide.
Method:
1. Place some sulfuric acid in a conical flask and warm it in a water bath.
2. Add a spatula of copper oxide powder to the acid and stir with a glass rod.
- Continue adding copper oxide powder until it is in excess.
4. Filter the mixture to remove the excess copper oxide.
5. Pour the filtrate ( the copper sulfate solution ) into an evaporating basin.
6. Heat the copper sulfate solution to evaporate half of the water.
7. Pour the solution into a watch glass and leave to allow all of the water to evaporate.
Core Practical 3: Preparing Copper Sulphate
Describe how you would investigate the electrolysis of Copper Sulphate solution with inert electrodes. ( Include Observations )
Aims - To investigate the electrolysis of copper sulfate solution using inert (unreactive) electrodes
1. Pour some copper sulfate solution into a beaker.
2. Place two graphite rods into the copper sulfate solution.
- Attach one electrode to the negative terminal of a dc supply, and the other electrode to the positive terminal.
3. Completely fill two small test tubes with copper sulfate solution and position a test tube over each electrode as shown in the diagram.
4. Turn on the power supply and observe what happens at each electrode.
5. Test any gas produced with a glowing splint and a burning splint.
Observations:
1. Negative Cathode: A brown/pink solid forms.
2. Positive Anode: Bubbles of a colourless gas form
- The gas relights a glowing splint
Core Practical 3: Preparing Copper Sulphate
Describe how you would investigate the electrolysis of Copper Sulphate with non-inert electrodes . ( Include Observations )
Aims - To investigate the electrolysis of copper sulfate solution using non-inert electrodes.
1. Pour some Copper Suphate solution into a beaker.
2. Measure and record the mass of 2 pieces of copper foil.
- Attach 1 to the negative terminal & another to the positive before dipping them into the Copper Sulphate solution.
3. Turn on the power supply, make sure it is a constant current.
- After 20mins, turn of power supply.
4. Carefully remove your electrodes while gently washing them with distilled water, then dip them into propanone.
- Lift the electrodes out & allow all the liquid to evaporate. Measure & record the mass of the electrode.
5. Repeat with fresh electrodes & different currents.
