Chem Past Paper -2 Flashcards by Harriet Dolby

What colour flame would sodium ions produce

Yellow

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Name a metal ion that would produce a green flame

Copper

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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

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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

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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

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What name is given to a useful prodcut such as methylated spirit

Formulation

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Suggest why pyridine 9unpleasant spell0 and methyl violet (make mixture purple) to make methylated spirit

To deter consumption/drinking by people

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Uses of methylated spirit

Fuel
Solvent
Antiseptic

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Describe how ethanol is produced from sugar soluton

Give the name of this process

Fermentation
Add yeast
Anaerobic conditions
Warm

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Name the gas produced when sodium is added to ethanol

Hydrogen

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Methanol is used to prodcue methanoic acid, what tupe of subtance reacts with methanol to produce methanoic acid

Oxidising agent

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Give the approximate temp used in haber process

450 C

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Pressure used in haber process

200 atm

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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

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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

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What is the problem in chromatography when line drawn in ink

Ink dissolves

Ink runs in solvent/water

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What is the problem with water used in chromatography

Colour will not dissolve/move

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Polyesters are produced when monomers join togetehr and lose a small molecule. Name this small molecule

Water

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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)

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Explain how carbon monoxide is produced when petrol is bruned in car engine

Incomplete combustion

Insufficenient limited o2 supply

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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

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Give one reason for having a max allowed prcentage of unburned hydrocarbons in exhaust fumes

Reduce health problems

Reduce global dimming

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Give two effects of atmospheric pollution which are reduced by using catalystic converters

acid rain
respiratory problems
carbon monoxide
global dimming/smog

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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

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Explainwhat happens to the yield of methanol if a temo higher than 250 is used

Smaller yield | Favours endothermic reaction

Sugggest why a catalyst is used in this industrial process

Less energy needed

Sugest the effect of using the catalyst on the equilibrium yield of methanol

No effect/change

Melamine is a ppolymer used to make non-disposable cups Melamine does not melt when it is heated Why

``` Thermosetting polymer Contains crosslinks (between polymer chains) ```

Suggest a suitable temp for the furnace in fractional distillation

Betwee 400-500

Suggest two reasons why bitumen is not used as fuel

- too viscous - not very flammable - bp too high

Conditions needed to crack hydrocarbon molecules from the diesel oil fraction

- high temp - steam - catalyst

Explain why large hydrocarbons cracked into smaller

- greater demand - smaller - more uselful, better fuel, used to make alkenes, used to make polymers

How to show presence of lithium ions experiment

crush tablets or dissolve tablet (in water or acid) • clean wire • place on wire • place in (roaring / blue / non-luminous) flame • observe flame colour • crimsonflame

What two pieces of meaasuring apparatus could the student use to fidn the rate of production of hydrogen gas

- gas syringe | - stopclock/stopwatch

Magnesium is fixed to some steel ships. Explain how this prevents the steel from rusting

- mg more reactibe | - provides sacraficial protection

Explain why aluminium windowframes do not corrode after they are made

- al has coating of aluminium oxide | - protects metal from further corrosion

Suggest reasons why wood is more sustainable than natural gas as a fuel for central heating boilers

wood is renewable or (natural) gas is finite (burning) wood produces the same amount of carbon dioxide as the trees absorbed or (burning natural) gas increases the amount of carbon dioxide (in the atmosphere

Name the function group of -COOH

Carboxylic acid

Monomer -OH and -COOH join to produce a polyester and small molecule - what is it

Water

Why does this type of polyester melt when it is heated

- thermosoftening | - no cross-links

Suggest why an outer skin is added to a polysester surf board

``` Make it -harder -stronger tougher -waterproof ```

Describe a test to show that the drinking water contained aluminium ions

add sodium hydroxide (solution to water sample) white precipitate (forms) (precipitate which is) soluble in excess (NaOH)

Plan an nvestigation to find the amss of dissolved solis in a fixed vollume of water

weigh (evaporating) basin / dish • add measured volume of water • weigh (evaporating) basin / dish and water • heat to evaporate water • reweigh • repeat heating until constant mass obtained • subtract mass of (evaporating) basin / dish from mass • repeat and calculate a mean, discarding anomalous results • calculate the mass in 100 cm3 water if necessary

Explain why organisms could not have evolved same way on titan as on earth- low o2 and co2 conc

Titan has) little / no oxygen (so) photosynthesis has not occurred (on Titan) (therefore) little / no carbon dioxide present (on Titan) or (therefore) oxygen-using animals cannot have evolved (on Titan)

Explaine how methane a greenhouse gas, keeps titan warmer than otehr moons that do not have atmosphere

methane) allows short(er) wavelength radiation to pass through (from the sun) (which is) re-emitted from the surface as long(er) wavelength radiation (which is) absorbed (by methane in the atmosphere

Why is a greater pressure not used in the haber process

• the energy costs would be high(er) • the equipment would need to be strong(er) • high(er) pressures are (more) dangerous

To test for sulfate ions the student added dilute hcl to copper sulfate solution. Name the solutio that would hsow the presence of sulfate ions when added to this micture

Barium chloride

Why filter water

Remove undisolved solids

How is liquid effluent processed

Aerobic biological treatment

How is solid sewage sludge proposed

Anaerobic digestion

Suggest reason why the total mass of processed solid sewage sludge increased between two dates

• the population increased • more waste water produced • less untreated sewage discharged

Between 1992 and 2010 the proportion of processed solid sewage sludge used as fertiliser increased. Suggest why

- increased demand for food (due to incrasing pop) - conserve energy/resources - landfill space is running out - increased demand for organic fertiliser

Compare two molecules n term of Structure and bonding Their reactions

- no. Atoms - no. Bonds - size of molecule - conbustion - reactions- addition

Which was could one increase the distance between the spots

- allow solvent front to travel further | - use a diff solvent

The manufacturers of greeen ink always use the same proportions of yellow dye and blue dye. Suggest why

-so that shade of green is the same | Or- green ink is a formulation

What will def produce a smaller rf value if the solvent and paper are both changed

- dye less soluble in new solvent | - more attracted new paper

Describe how ceramic food plates are produced from clay

- clay is shapes | - heated in furnace

Ethanoic acid ionises in water | CH3COOH(aq) CH3COO-(aq) + H+(aq)

- incomplete/partial ionisation | - reaction is reversible

Methaoic acid

HCOOH

CH3CH2COOH

Propanoic aci

Give name of the ester produced when ethanoic acid reacts when ethanol

Ethyl ethanoate

The student concluded that the large calcium carbonate lumps reacted more slowly than the small calcium carbonate lumps. How do the students result show that this conclusion is correct?

(for large lumps) a smaller number of moles of gas is collected in the same time or (for large lumps) more time is needed to collect the same number of moles of gas or the line (of best fit for large lumps) is less steep

Glycine reacts by condensation polymerisation to produce a polypetide and one other substance. Name other substance produced

Water

Which gases from earths early atmosphere could have produced this element glycine for algea

Ammonia | Nitrogen

Describe the shape and structure of dna

two polymer chains four (different) monomers / nucleotides (double) helix

Give the name of the solvent used to dssolve the ions in this reaction

Water

Explain why a change in pressure doesnt affect the colour of the equilibrium mixture

no change in equilibrium position | (because) no gases are present

Suggest why uisng solar energy is a more suistainable way of generating electricity than burning oil

Solar is renewable source of energy

solar energy may nit be able to replace the generation of electricity from fossil fuels completely? Suggestwhy

- sunshine unreliable - increased demand for enrgy - lack of space

Each student did the chomatography investigation differently. Rf values diff. How did the investigations differ

Dff solvent used

What is the stationary phase in paper chromatography

Paper

How can diff forms of poly(ethene) be produced from ethene

-use diff reaction conditions

Explain why HDPE has a higher densiity than LDPE

HDPE polymer chains/ molecules are closer together | -more atoms per unit volume

Name soluble salt produced when calcium phosphate reacts w/ nitric acid

Calcium nitrate

Name soluble salt produced when calcium phosphate reacts w/ phosphoric acid

Triple superphosphate

Suggest reasons why recylcling scrap copper is a more ssustainable 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 phytoming

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 of solution (containing a copper compound) or displacement (of copper) from solution (containing a copper compound)

Ohytomining has not been widely used to extract copper - suggest why

high grade ores still available • land not available | • phytomining takes a long time • new technology

Explain why the lines of best fit become horizontal

- reactionhas stopped | - reactant is used up

The activation energy for the reaction between zinc and sulfuric acid is lowered if a solution containinng meal ions is added. What is the most likely formula of. metal ions added

CU2+

Describe conditions needed for cracking

- high temp | - steam/catalyst

Butanil can be produced from sugar solution by adding bacteria. Sugar solution is broken down in similar ways by bacteria and by yeast Suggest reaction conditions needed

- warm | - anaerobic conditions

Chem Past Paper -2 Flashcards

(82 cards)