p2 exam questions Flashcards
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
give two effects of atmospheric pollution which are reduced by breaking down nitrogen oxides
- acid rain
- respiratory problems
- global dimming
- carbon monoxide
suggest why a catalyst is used - dont answer in terms of increasing RoR
less energy is needed
suggest effect of using catalyst on equilibrium yield
no effect
describe a test to show that drinking water contains aluminium ions. give the result of the test
- add sodium hydroxide solution to water sample
- white precipitate forms
- which is soluble in excess NaOH
plan an investigation to find the total mass of dissolved solids in a 100cm3 sample of drinking water
- weigh evaporating basin
- add measured volume of water
- weigh evaporating basin and water
- heat to evaporate water
- reweigh
- repeat heating until constant mass obtained
- subtract mass of evaporating basin from mass
- repeat and calculate a mean, discarding anomalous results
- calculate the mass in 100cm3 water if necessary
plan an investigation to show how the conc of sodium thiosulfate solution affects the RoR with dilute hydrochloric acid
- measure indicated volume of sodium thiosuflate
- place in conical flask
- measure indicated volume of hydrochloric acid
- place on cross
- add hydrochloric acid to conical flask
- swirl
- start stopwatch
- measure time for cross to become no longer visible
- repeat and find mean
- repeat for different concentrations of sodium thiosulfate
control variables:
- conc of hydrochloric acid
- volume of hydrochloric acid
- total volume of sodium thiosulfate solution
suggest two reasons why only two spots are seen on a chromatography paper
- some of the compounds are colourless in solution
- dyes have the same rf values
suggest two pieces of information about energy usage which would help to produce a complete LCA
energy used in:
- extraction of raw materials
- processing raw materials
- manufacturing
- transportation
- cleaning non-disposable plates
- disposal
- recycling
explain how reducing the amount of sulfur in fossil fuels reduces the erosion of limestone
- sulfur reacts with oxygen to form sulfur dioxide
- so less sulfur dioxide emitted
- so less acid rain
- so less limestone reacts with acid rain
solar energy may not be able to replace the generation of electricity from fossil fuels completely. suggest two reasons why
- sunshine is unreliable
- increased demand for energy
- lack of space
plan an investigation to determine the Rf value for the dye in this food colouring
- draw pencil start line on chromatography paper
- place spot of food colouring on start line
- using capillary tube
- use of suitable solvent
- place solvent in beaker
- place chromatography paper in beaker
- so chromatography paper is in solvent
- but solvent is below start line
- use a lid
- wait for solvent to travel up the chromatography paper until near top
- mark solvent front
- dry chromatography paper
- measure distance between start line and centre of spot
- measure distance between start line and solvent front
- divide first distance by second distance to determine Rf value
explain why HDPE has a higher density than LDPE
- polymer chains in HDPE are closer together
- so more atoms per unit volume
suggest three reasons why recycling scrap copper is a more sustainable way of obtaining copper than processing copper ores
- recycling conserves copper ores
- recycling uses less energy
- recycling reduces waste
- mining / quarrying cause environmental impacts
describe how copper is extracted from low-grade ores by phytomining
- grow plants on land containing copper ores
- plants are burnt to produce ash
- ash dissolved in acid to produce a solution of a copper compound
- electrolysis / displacement
