Paper 1 RQPs Flashcards
what is the aim of the making salts practical?
preparation of a pure, dry sample of a soluble salt from an insoluble oxide or carbonate using a Bunsen burner to heat dilute acid and a water bath or electric heater to evaporate the solution
what is the equipment list for the making salts practical? [15]
1.0 M dilute sulfuric acid
Copper (II) oxide powder
Spatula
Glass rod
Measuring cylinder
2 beakers: 100 cm3 and 250 cm3
Bunsen burner, tripod, gauze, heatproof mat
Filter funnel, paper, a small conical flask
Evaporating basin
Crystallising dish
what is the method for the making salts practical [7]?
- Measure 20 cm3 H₂SO₄ into measuring cylinder then pour into beaker.
- Heat acid gently over Bunsen burner.
- Add small amounts of insoluble base (CuO) in excess (no more effervescence is produced/some remains and doesn’t dissolve after stirring)
- Filter solution to remove the excess CuO.
- Pour solution into evaporating basin and use a water bath until crystals start to form.
- Leave evaporating basin (crystallising dish) in a cool place for at least 24 hours.
- Gently pat the crystals dry between two pieces of filter paper
what safety precautions need to be taken in the making salts practical?
Wear safety goggles and an apron (H₂SO₄ is corrosive); tie hair back; when the Bunsen burner is not in use, turn it off or leave it on the orange safety flame.
what is the aim of the neutralisation practical?
to find the concentration of a dilute H₂SO₄ solution, using a NaOH solution of known concentration.
CuO + H₂SO₄ = ?
CuSO₄ + H₂O
H₂SO₄ + 2NaOH = ?
Na₂SO₄ + 2H₂O
what is the equipment list for the neutralisation practical? [9]
25 cm3 volumetric pipette,pipette filler
50 cm3 burette
250 cm3 conical flask
Small funnel, clamp stand and clamp, white tile
0.1 M sodium hydroxide solution
Sulfuric acid
Phenolphthalein indicator (OR Methyl Orange [red in acid, yellow in alkali] OR Litmus Blue [red in acid, blue in alkali])
what is the method for the neutralisation practical [12]?
- Use pipette to measure 25cm3 of NaOH into conical flask and place on white tile
- Fill burette with H₂SO₄ using a funnel
- Remove funnel and record initial reading of acid in burette (always from bottom of meniscus)
- Add 5 drops of indicator (phenolphthalein) to conical flask
- Slowly open burette tap, while swirling conical flask
- Add acid dropwise near endpoint (colour will start to change slightly)
- Close burette when colour change occurs (pink to colourless)
- Record final reading of acid in burette and calculate titre (volume of acid used to neutralise alkali)
- Repeat until concordant results achieved (within 0.1cm3 of each other)
- Present results in table and calculate mean titre (discard anomalies)
- Calculate number of moles of NaOH used - to find moles of H₂SO₄ : balanced equation has ratio 2:1 so divide the moles of NaOH by 2.
- Use the formula [c= n/v] to work out the concentration of H₂SO₄
what are some safety precautions that need to be taken in the neutralisation practical?
Wear safety goggles (acid/alkali); tie hair back; report any broken glassware immediately; fill burette below eye-level so it doesn’t splash in face
what is the aim of the electrolysis practical?
Investigate what happens when aqueous solutions are electrolysed using inert electrodes
what is the equipment list for the electrolysis practical? [[9]
0.5 M copper(II) chloride solution
0.5 M sodium chloride solution
Petri dish lid with bored holes, 2 carbon rod electrodes with support bungs, 2 crocodile plug leads
Low voltage power supply
Blue litmus paper
Forceps
what is the method for the electrolysis practical? [6]
- Add ~50cm3 of copper or sodium chloride solution to beaker, add lid and insert electrodes through the holes (make sure they don’t touch)
- Attach crocodile leads to electrodes and connect to DC terminals of low voltage power supply
- Set power supply to 4V and switch on.
- Using forceps, hold litmus paper near the positive electrode.
- After a few minutes, turn power supply off and observe negative electrode
6, Record observations at the electrodes.
what would be observed at the positive electrode, in the electrolysis of copper (II) chloride?
- chlorine gas formed
- bubbles of gas
- bleaches blue litmus white
what would be observed at the positive electrode, in the electrolysis of sodium chloride?
- chlorine gas formed
- bubbles of gas
- bleaches blue litmus white