C2

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What are the advantages of gas chromatography over paper chromatography?
Rapid / quick, accurate, sensitive or detects very small quantities.
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What does mass spectroscopy give?
Identifies solvents / compounds / substances.
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Describe a method for making crystals of potassium chloride from potassium hydroxide solution and hydrochloric acid. (Describe how you will neutralise the potassium hydrochloric solution and how you will get crystals of potassium chloride)
Reagent in beaker. Add indicator. Add other reagent. Swirl. Add dropwise near end. Stop at change of colour. Note volume added. Repeat without indicator, add same volume of reagent. Pour solution into basin. Heat. Leave to crystallise/evaporate.
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Why do some farmers put ammonium nitrate on their farmland?
Because it is a fertiliser / helps plants grow.
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Why does an increase in temperature increase the rate of reaction?
Because the particles have more energy / move faster. So particles collide more frequently or are more likely to collide. More of the collisions are successful or more of the particles have the activation energy.
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Carbon dioxide has a very low boiling point. Explain why.
Because carbon dioxide is simple molecular / small molecules. There are intermolecular forces (between the molecules). So a small amount of energy needed (to separate molecules) or (intermolecular forces) are weak.
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Gold is rare and expensive. Why is it still used in industrial processes?
Gold is the only catalyst for some reactions. Catalysts are not used up. Improves speed of reaction. Reduces amount of energy or process needs low(er) temperature. Only small quantities (of catalyst) needed.
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Why does electrolyte contain cryolite?
Because it lowers the melting point (of the aluminium oxide) so less energy is needed (to melt it).
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Calcium hydroxide has the formula Ca(OH)2. Why are there two hydroxide ions for each calcium ion in the formula?
Because calcium is +2 and hydroxide is –1 or to make the compound neutral (in terms of charges).
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What is a nanoparticle?
Particles of size 1-100 nm / particles with a few hundred atoms / particles with a high surface area (to volume ratio) / has different properties to ‘normal’ size particles of the same substance.
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Why is graphite softer than diamond?
Because the layers (of carbon atoms) in graphite can slide as there are only weak intermolecular forces or weak forces between layers. However, in diamond, each carbon atom is (strongly / covalently) bonded to 4 others so no atoms can slide.
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What is the ionic equation for the neutralisation reaction?
H+ + OH– → H2O
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Describe how gas chromatography can separate substances in a mixture of compounds.
Substances carried by gas, through column / coil / tube or through solid material / powder, at different speeds.
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How is aluminium and carbon dioxide formed in the electrolysis of aluminium oxide?
Aluminium oxide melted. Al ions attracted to -electrode. At -electrode Al is formed/Al ions gain electrons. Oxide ions attracted to +electrode. O2 formed at +electrode/oxide ions lose electrons. O2 reacts with C to make CO2/CO2 formed at +electrode.
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Suggest a suitable chemical that could be added to the water to provide OH- ions.
Sodium hydroxide / potassium, hydroxide / alkali / a hydroxide.
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Explain why ammonia (NH3) has a low boiling point.
Because ammonia is made of small molecules / simple molecules / simple molecular structures. So there are weak forces between the molecules or so the intermolecular forces are weak.
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Describe and explain how used plastic bottles (made out of thermosoftening plastic) can be changed into new plastic objects.
Used plastic bottles are heated then moulded / extruded into a new shape / object because the polymer chains / molecules in the plastic have weak intermolecular forces that allow these polymer chains / molecules to become mobile when heated.
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Other cards in this set

Card 2

Front

What does mass spectroscopy give?

Back

Identifies solvents / compounds / substances.

Card 3

Front

Describe a method for making crystals of potassium chloride from potassium hydroxide solution and hydrochloric acid. (Describe how you will neutralise the potassium hydrochloric solution and how you will get crystals of potassium chloride)

Back

Preview of the front of card 3

Card 4

Front

Why do some farmers put ammonium nitrate on their farmland?

Back

Preview of the front of card 4

Card 5

Front

Why does an increase in temperature increase the rate of reaction?

Back

Preview of the front of card 5
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