paper 2 qu's Flashcards
(19 cards)
Silver nitrate solution and dilute nitric acid are added to the solution. A cream precipitate forms. Which ion is shown to be present by the cream precipitate?
bromide ion
Describe how ethanol is produced from sugar solution. Give the name of this process (3)
*fermentation
*add yeast
*anaerobic conditions
Name the gas produced when sodium is added to ethanol
hydrogen
Methanol is used to produce methanoic acid. What type of substance reacts with methanol to produce methanoic acid?
oxidising agent
In the Haber process, the mixture of gases from the reactor cools in the condenser. Suggest why ammonia condenses but the other gases do not.
ammonia has a higher boiling point
The % of CO2 and O2 have changed from Earth’s early atmosphere to Earth’s atmosphere today. Explain the processes that led to these changes. (6)
**changes
*CO2 has decreased
*oxygen has increased
**processes
*volcanic activity released water vapour
*water vapour condensed to form oceans
*carbonates produce sediments
*carbon locked up in sedimentary rocks
*algae and plants absorbed CO2
*by photosynthesis
*which also released oxygen
*carbon locked up in fossil fuels
Why are scientists not certain about the % of each gas in the Earth’s early atmosphere?
limited or no evidence
Polymers are produced when monomers join together and lose a small molecule. Name the small molecule lost.
water
Carpets are made from poly(propene), wool or a mixture of both. Poly(propene) wears out more slowly than wool. A mixture of poly(propene) and wool to make carpets is more sustainable than using just poly(propene) or just wool. Suggest why. (2)
*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
Suggest tow reasons why the maximum allowed percentage of CO has been decreased for newer cars. (2)
*CO is poisonous
*greater public concern about pollution
*more cars so otherwise there would be more CO entering the atmosphere
Give one reason for having a maximum allowed percentage of unburned hydrocarbons in exhaust fumes
to reduce health problems
Describe how oxides of nitrogen are produced when petrol is burned in car engines (2)
*nitrogen from the atmosphere reacts with oxygen from the atmosphere
*at high temperature in engine
Give two effects of atmospheric pollution which are reduced by using catalytic converters
*acid rain
*respiratory problems
*carbon monoxide
*global dimming
The reaction (CO(g) + 2H2(g) ⇌ CH3OH(g)) is carried out at a temperature of 250 ºC and a pressure of 100 atmospheres. The forward reaction is exothermic. Explain what happens to the yield of methanol if a temperature higher than 250 ºC is used. (2)
*smaller yield
*favours endothermic reaction
A pressure of 100 atmospheres is used instead of atmospheric pressure. The higher pressure gives a greater yield of methanol and an increased rate of
reaction. Explain why. (4)
*equilibrium position moves to the product side
*because fewer molecules on product side
*more collisions per unit time
*because more molecules per unit volume
A catalyst is used in the reaction to produce methanol from carbon monoxide
and hydrogen. Explain how a catalyst increases the rate of a reaction (2)
*provides a different reaction pathway
*which has a lower activation energy
Suggest why a catalyst is used in this industrial process. Do not give answers in terms of increasing the rate of reaction.
less energy is needed
Suggest the effect of using the catalyst on the equilibrium yield of methanol.
no effect
Melamine is a polymer used to make non-disposable cups. Melamine does not melt when it is heated. Explain why. (2)
*thermosetting polymer
*contains bonds between polymer chains
