Chem Past Paper -2
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卡片预览 (24 张)
What colour flame would sodium ions produce
Yellow
Name a metal ion that would produce a green flame
Copper
Some fireworks contain a mixture of metal ions. Why is it difficult to identify the metal ions from the colour of the flames
Colours are masked
Silver nitrate solution and dilute nitric acid are added t the solution. A cream precipitate forms. Which ion s shown to be present by the cream precipitate
Bromide
Descrive a test to show the presence ofsulfate ions in the solution. Give the result of the test if there are suklflate ions in the solution
add barium chloride (solution) add hydrochloric acid white precipitate produced
What name is given to a useful prodcut such as methylated spirit
Formulation
Suggest why pyridine 9unpleasant spell0 and methyl violet (make mixture purple) to make methylated spirit
To deter consumption/drinking by people
Uses of methylated spirit
Fuel Solvent Antiseptic
Describe how ethanol is produced from sugar soluton Give the name of this process
Fermentation Add yeast Anaerobic conditions Warm
Name the gas produced when sodium is added to ethanol
Hydrogen
Methanol is used to prodcue methanoic acid, what tupe of subtance reacts with methanol to produce methanoic acid
Oxidising agent
Give the approximate temp used in haber process
450 C
Pressure used in haber process
200 atm
The mixture of gases from the reactor cools in the condensor Suggest why ammonia condenses but the other gases do not
Ammonia has a higher bp
Why are scientist not certain about the percentage of each gas in the earth early atmosphere
Occured 4.6 bn years ago Limited or no evidence
What is the problem in chromatography when line drawn in ink
Ink dissolves Ink runs in solvent/water
What is the problem with water used in chromatography
Colour will not dissolve/move
Polyesters are produced when monomers join togetehr and lose a small molecule. Name this small molecule
Water
Why is a mixture of poly(propene) and wool is used to make carpets is more sustainable than using just one of the materials
poly(propene) comes from a non-renewable source • poly(propene) requires a lot of energy to make • poly(propene) is not biodegradable • a wool carpet needs replacing more often • wool requires the use of large areas of land (which could be used to grow food crops)
Explain how carbon monoxide is produced when petrol is bruned in car engine
Incomplete combustion Insufficenient limited o2 supply
Suggest two reasons why maximum allowed percentage of carbonn monoxide has been decreased for newer cars
carbon monoxide toxic / poisonous • greater public concern / awareness about pollution • more cars so otherwise there would be more carbon monoxide entering atmosphere • improved engine technology • catalytic converters have been introduced
Give one reason for having a max allowed prcentage of unburned hydrocarbons in exhaust fumes
Reduce health problems Reduce global dimming
Give two effects of atmospheric pollution which are reduced by using catalystic converters
• acid rain • respiratory problems • carbon monoxide • global dimming/smog
The catalyst in catalytic converters is a mixture in three elements. Where is the periodic table are these elements most likely to be found
Transition metals