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Chemistry > 3-6 Marker > Flashcards

3-6 Marker Flashcards

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1
Q

Explain in terms of particles, why the rate of reaction decreases during any reaction (3)

A

• as reaction progresses, concentration of particles decreases
• frequency of collisions decreases
• chance of successful collisions decreases

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2
Q

Explain what happens to the mass of the products as the reaction progresses between marble and hydrochloric acid in a conical flask (3)

A

• mass will decrease
• as carbon dioxide is produced
• which escapes from the conical flask / less products in the
conical flask

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3
Q

Describe how you can measure the rate at which the mixture goes cloudy when sodium thiosulfate reacts with sulfuric acid 3)

A

• put a flask on top of a cross
• record/measure time
• when cross cannot be seen/blocked/obscured/disappears

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4
Q

When reacting magnesium with sulfuric acid the products are magnesium sulfate and hydrogen gas. Describe, step by step, how you would carry out an experiment to test if the following prediction is true:
“If I halve the concentration of sulfuric acid, the rate of reaction will halve.” (6)

A

• measure the same volumes of sulfuric acid using a burette/pipette/measuring cylinder
• measure the same masses of magnesium using a top-pan balance/scales
• pour acid into a conical flask
• measure and record the starting temperature of the sulfuric acid
• same starting temperature must be used for each experiment
• thermometer
• add the magnesium to the sulfuric acid/conical flask
• then immediately seal the conical flask with a bung and delivery tube
• start timer when magnesium added
• delivery tube connected to syringe/inverted measuring cylinder
• measure volume of gas
• every regular interval of time e.g. 5s or 10s
• measure and record the highest temperature reached
• final temperature - starting temperature = temperature change
• repeat experiment with different concentrations of sulfuric acid

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5
Q

The method below has been used to investigate the rate of reaction when reacting sodium thiosulfate with hydrochloric acid:
1. A conical flask is used to measure 15 cm3 of cold sodium thiosulfate solution and hydrochloric acid
2. Measure the temperature of the corridor
3. Put the conical flask on a grey cross
4. Start counting when the reaction begins
5. Repeat the experiment using a measuring cylinder
6. Stop counting when the cross cannot be seen

A

• in step 1 use a measuring cylinder to measure 15 cm? of sodium thiosulfate and not a conical flask
• in step 2 the starting temperature of the reactants should be measured and not the corridor
• in step 3 a black cross should be used
• in step 4 a timer should be used instead of counting
• in step 5 a measuring cylinder is now being used and should have been a conical flask as this was used in step 1

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6
Q

Explain why a lower concentration of reactants results in a different rate of reaction compared to a higher concentration of reactants (3)

A

• slower rate of reaction in lower concentration
• less acid particles / slower reaction because of less frequent
collisions
• lower volumes of gas formed

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7
Q

Explain why increasing the temperature increases the rate of reaction (4)

A

• particles store more energy / move faster
• particles to collide more frequently
• higher percentage of particles have energy greater than the activation energy
• increases the chance of successful collisions

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8
Q

Explain why increasing the temperature increases the rate of reaction (4)

A

• particles store more energy / move faster
• particles to collide more frequently
• higher percentage of particles have energy greater than the
activation energy
• increases the chance of successful collisions

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9
Q

Explain how the size
of reactants changes the rate of a chemical reaction (3)

A

• smaller reactants have larger surface area/surface area to volume ratio/more points of contact
• frequency of collisions increases
• chance of successful collisions increases

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10
Q

Explain why increasing the surface area increases the rate of reaction (3)

A

• more points of contact between reactants / particles more
exposed
• increases frequency of collisions
• increases chance of successful collisions

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11
Q

Explain how catalysts increase the rate of reaction (3)

A

• lowering the activation energy
• providing an alternative reaction pathway
• higher percentage of particles have more energy than the activation energy
• increases the chance of successful collisions

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12
Q

Cars contain catalvtic converters
Explain why transition metals are coated on a honeycomb structure 3)

A

• honevcomb structure increases the surface area to volume
ratio
• catalysts in contact more with harmful gases
• increases rate of reaction
• less harmful gases released into atmosphere

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13
Q

Describe how you would show the reaction between hydrated copper sulfate and anhydrous copper sulfate is a reversible reaction (4)

A

• heat the hydrated copper sulfate (to form anhydrous copper sulfate)
• (anhydrous copper sulfate) is white/water or steam seen when hydrated copper sulfate heated
• (to form hydrated copper sulfate from anhydrous copper sulfate) you add water
• (hydrated copper sulfate) is blue

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14
Q

Explain what happens to the equilibrium when the concentration of BiCIz is increased (4)

A

• equilibrium shifts/moves/changes/no longer in equilibrium
• to right side / in forward reaction
• producing more products / decreasing reactants
• new equilibrium formed

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15
Q

Describe how to carry out chromatography in the laboratory and how to calculate the Rf value of the food colourings you separate (6)

A

• get the filter paper and draw the start line in pencil
• spots of food colouring must be widely spaced apart on the start line
• label vour food colourings
• use water as the solvent (or any other suitable solvent)
• water goes into the container e.g. beaker
• filter paper is then placed into the container
• start line above the solvent
• solvent will rise up the paper
• leave the paper to drv
• use a ruler to measure the distance from start line to solvent front
• use a ruler to measure the distance from start line to the centre of the spot
• Rf value = distance travelled by spot / distance travelled by solvent

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16
Q

Explain the appearance for the blue ink in this chromatogram (6)

A

• ink has 3 spots above the start line
• so blue ink is a mixture
• spots in blue ink finish at same level as other inks
• blue ink contains green ink, yellow ink and orange ink
• green ink most soluble
• ink does not leave start line so is insoluble
• no violet or red ink in mixture of blue ink

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17
Q

Describe what happens if more and more sodium hydroxide is added to the calcium and magnesium precipitates and how they can be distinguished (4)

A

• sodium hydroxide does not dissolve
• use a flame test
• calcium = orange/red
• magnesium = no colour

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18
Q

Describe how you can prove the presence of sulfate ions in a solution (3)

A

• first add hydrochloric acid
• then add barium chloride solution
• a white precipitate will be produced forms

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19
Q

Describe how you can prove the presence of chloride, bromide and iodide ions in a solution (5)

A

• first add nitric acid
• then add silver nitrate solution
• chloride ions = white precipitate
• bromide ions = cream precipitate
• iodide ions = yellow precipitate

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20
Q

Describe how you would prove which gas is produced when a carboxylic acid reacts with a metal carbonate (3)

A

• limewater test to identify carbon dioxide
(S) Negative lons: Carbonate lons
• colourless to
• cloudy/milky white

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21
Q

Describe how instrumental methods are better to use compared to chemical tests (4)

A

• more reliable / more efficient
• can use small amount
• more sensitive / precise
• can continuously be left on
• fast results

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22
Q

Explain why there was a lot of water vapour in Earth’s early atmosphere (3)

A

• volcanic activity
• caused temperature of atmosphere to be above 100 degrees
Celsius
• water vapour could not condense into a liquid

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23
Q

Explain how oceans formed in
Earth’s early atmosphere (3)

A

• water vapour condensed into clouds
• rained
• forming oceans

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24
Q

Explain how the composition of Earth’s early atmosphere changed
Refer to the gases carbon dioxide, oxygen and nitrogen (6)

A

• carbon dioxide decreased because of photosvnthesis
• cyanobacteria/algae/plants take carbon dioxide in from atmosphere
• fossil fuels such as oil/gas/coal store carbon
• carbon dioxide dissolved in oceans
• carbonates in oceans store carbon / sedimentarv limestone rocks store carbon
• oxygen increased because of photosynthesis
• due to cvanobacteria/algae/plants producing oxvgen
• nitrogen increased due to ammonia converted into nitrogen
• volcanoes release nitrogen
• bacteria produce nitrogen

25
Q

Explain what has caused carbon dioxide to increase in today’s atmosphere (4)

A

• burning/combustion of fossil fuels increases carbon dioxide
• respiration increases carbon dioxide
• volcanic eruptions/activity increases carbon dioxide
• deforestation increases carbon dioxide as less photosvnthesis
• photosynthesis decreases carbon dioxide
• carbon dioxide dissolving oceans decreases carbon dioxide in atmosphere

26
Q

Describe how the greenhouse effect works (4)

A

• short wavelength radiation enters the atmosphere
Greenhouse Effect
• absorbed
• longer wavelength radiation re-emitted / Earth’s surface re-emits longer wavelengths
• absorbed by greenhouse gases/carbon dioxide/methane
causing temperature increase/rise

27
Q

Describe six potential effects of climate change (6)

A

• global warming as temperature rise
• ice caps/glaciers melt
• causing sea levels to rise
• leading to flooding/coastal erosion
• weather can become more extreme
• causing drought/famine
• forest fires
• where habitats of animals can be lost/destroved
• which can lead to species becoming extinct/reduction in biodiversitv
• as well as problems with farming/agriculture

28
Q

Explain how a more concentrated solution of ethanol produced by fermentation can be obtained (4)

A

• (vou must use) fractional distillation
• then heat the solution of ethanol
• distillations will happen several times in the fractionating column
• the vapour at the top of fractionating column will be more concentrated with alcohol compared to the original ethanol solution
• you finally need to condense the vapour to obtain concentrated solution

29
Q

Describe how phytomining extracts copper from low-grade ores (4)

A

• plants are grown
• burn the plants
• add ash to sulfuric acid (to produce leachate)
• add scrap iron to copper sulfate solution / electrolvsis of copper sulfate solution

30
Q

Give six reasons why recycling copper is more sustainable than extracting copper from copper-rich ores (6)

A

• copper is a finite resource
• copper ores conserved
• decreases use of landfill
• less energy used
• waste decreased compared to mining
• less mining
• less greenhouse gases
• causes less damage to habitats/landscape
• uses less fossil fuels

31
Q

Explain the advantages of recycling iron and aluminium, instead of heating iron with carbon and extracting aluminium by electrolysis (6)

A

• extracting metals from ores produces more carbon dioxide than recycling (higher carbon footorint)
• recycling produces less greenhouse gases
• so less global warming
• extracting metals from ores uses more energy
• electrolysis uses a lot of electricity
• electricity is expensive
• extracting iron from its ore uses large amounts of heat energy
• recycling decreases waste in landfill sites
• recycling causes less damage to habitats/landscape
• recycling means there is less mining for ores
• recvcling conserves natural resources / keeps natural resources in the crust/ground
• recycling uses less energy/power
• so uses less fossil fuels

32
Q

Explain what will happen to each iron nail after they are left in the test tubes for two weeks (6)

A

• Iron nail in tube A does not rust/no rusting
• drying agent absorbs water
• no water in tube A (so no rusting)
• Iron nail in tube B does not rust/no rusting
• as oil prevents air being absorbed
• no oxygen in tube B as oxygen removed by boiling water (so no rusting)
• iron nail in tube C rusts
• tube C has oxygen/air and water
• water AND air are required for rusting

33
Q

Explain why alloys are stronger than pure metals (3)

A

• in allovs the different atoms have different sizes
• distorts regular structure
• more difficult for lavers to slide past each other

34
Q

Explain how ceramics are made (3)

A

• clay is mixed with water to make wet clay
• wet clay is moulded into specific shapes
• clay put into a furnace heated and hardens

35
Q

Explain why ceramics can easily be cracked with a small knock 3)

A

• layers easily distorted with a knock
• causes same charged ions in the layers to move closer together
• same charged ions repel each other

36
Q

Explain what happens to the yield of ammonia formed at equilibrium if the pressure is increased (3)

A

• amount/vield of ammonia increases
• equilibrium moves to the side with fewer molecules
• favouring the forward direction

37
Q

In the Haber process, explain why a higher pressure than 200 atm is not used (3)

A

• higher costs/energy
• increased risk of explosion
• compromise of 200 atm is used

38
Q

In the Haber process, explain why 450 degrees Celsius is used and not a lower temperature (4)

A

• forward reaction is exothermic
• so an increased temperature lowers the yield of ammonia
• whereas a lower temperature decreases the rate of reaction
• compromise of 450 degrees Celsius is used

39
Q

In the Haber process, explain why a much lower temperature is not used (3)

A

• (lower temperatures) the rate is too slow
• as particles do not collide as often
• fewer particles have the activation energy
• decreasing chance of successful collisions

40
Q

Explain why iron is used in the Haber process (4)

A

• iron is used as a catalvst
• speeding up the rate of reaction by providing an alternative reaction pathway
• lowers the activation energy
• so a lower temperature can be used

41
Q

You must discuss how changing the conditions affects the:
• rate of attainment of equilibrium
• equilibrium vield of ammonia

A

• (forward reaction is exothermic) so an increased temperature lowers the yield of ammonia
• whereas a lower temperature decreases the rate of reaction
• (lower temperatures) the rate is too slow
• as particles do not collide as often
• fewer particles have the activation energy
• decreasing chance of successful collisions
• compromise of 450 degrees Celsius is used
• (higher pressure of 200 am) means amount/vield of ammonia increases
• as equilibrium moves to the side with fewer molecules
• favouring the forward direction
• (iron used as a catalyst) speeds up the rate of reaction by providing an alternative reaction pathwav
• lowers the activation energy
• so a lower temperature can be used

42
Q

Explain why propane, butane and pentane are members of the same homologous series (3)

A

• same general formula/CH2n+2
• each formula is different by CH2
• similar physical properties/increases in boiling point as alcohol becomes longer
• each alkane reacts in similar ways/each alkane combusts completely to produce carbon dioxide and water/similar
chemical reactions

43
Q

Compare methane and butane discussing their structure and bonding (6)

A

• methane and butane both hydrocarbons
• belong to same homologous series
• methane has no covalent bonds between carbon atoms
• methane and butane both have contain C-H bonds
• methane has 1 carbon atom whereas butane has 4
• methane has 4 hydrogen atoms whereas butane has 10
• simple molecules
• both have weak (intermolecular) forces between molecules
• flammable
• methane and butane gases at room temperature/low boiling points
• methane and butane do not conduct electricitv

44
Q

Describe how crude oil can be separated into their individual fractions (4)

A

•heat/boil/vaporise
•column is cooler at the top / hotter at the bottom
•condenses
as fractions go below boiling point / at different levels

45
Q

Explain how the experiment below can be used to prove the products of complete combustion of methane (4)

A

• ice condenses water vapour
• water causes anhydrous copper sulfate to become blue
• limewater is colourless
• carbon dioxide makes limewater cloudy/white milky

46
Q

Compare and contrast why complete combustion of methane needs to happen instead of incomplete combustion (6)

A

• complete combustion happens in a lot of air/oxygen
• the products of complete combustion are carbon dioxide and water only
• carbon dioxide does not harm vou
• but carbon dioxide is a greenhouse gas
• which contributes to global warming
• incomplete combustion happens in a limited air/oxygen
• incomplete combustion produces toxic (gas) of carbon monoxide
• carbon monoxide combines with haemoglobin decreasing amount of oxygen in blood
• can causes unconsciousness/death
• as carbon monoxide is colourless so cannot be seen
• carbon monoxide is odourless so cannot be smelt
• incomplete combustion produces particulates/carbon/soot
• soot darkens buildings/makes them dirtv
• soot causes breathing problems (as gets into lungs)

47
Q

Describe how combustion of fossil fuels causes problems in the environment (3)

A

• sulfur combines with oxygen producing sulfur dioxide
• sulfur dioxide dissolves in clouds forming sulfuric
acid/sulfurous acid/acidic solution
• buildings/limestone damaged
• crops damaged/trees/plants are damaged
• lakes become more acidic/fish are killed

48
Q

Outline how pollutants released from petrol cars can cause damage to the environment and how catalytic converters help reduce emissions (6)

A

• carbon monoxide is toxic as combines with haemoglobin
• soot/particulates makes breathing more difficult/darkens buildings making them more dirtv
• carbon monoxide converted to carbon dioxide
• carbon dioxide is released which is a greenhouse gas
• greenhouse gases cause global warming
• global warming causes sea level rises, melting ice caps, more extreme weather etc…
• nitrogen oxides are released which are acidic
• nitrogen oxides contribute to acid rain
• acid rain kills plants, damages crops, damages buildings
• decreases carbon monoxide emissions
• decreases nitrogen oxides emissions
• less harmful gases released into atmosphere
• nitrogen oxides converted to nitrogen

49
Q

Soot damages the lungs causing breathing problems
Explain how else incomplete combustion can be dangerous for people (3)

A

• carbon monoxide is toxic/ poisonous
• decreases amount of oxygen in blood
• carbon monoxide combines with haemoglobin
• unconscious/die

50
Q

Explain what happens in
catalytic cracking of long alkanes (4)

A

• pass evaporated fraction over an aluminium oxide catalyst
• roughly 650 degrees Celsius
• breaks covalent bonds between carbon atoms
• products are shorter alkane and a small alkene

51
Q

Explain what happens in
steam cracking of long alkanes (3)

A

• steam breaks covalent bonds between carbon atoms
• into a shorter chained alkane and a small alkene
• 400 degrees Celsius

52
Q

Explain why propene can form polymers but propane cannot (3)

A

• propene/alkenes have double bonds/unsaturated
• propane/alkanes have single bonds/saturated
• alkenes are reactive/can bond to other alkenes

53
Q

Describe how you would test for an alkene and alkane using bromine water (3)

A

• bromine water is orange/yellow/red-brown/brown-red/brown
• alkene causes bromine water to become colourless/no colour
• alkane causes bromine water to stay orange/vellow/red-brown/brown-red/brown/no colour change

54
Q

Describe the conditions needed to make ethene into ethanol (3)

A

• heat
• high pressure
• catalyst

55
Q

Explain how poly(ethene) is formed (4)

A

• many ethene molecules Making Polymers
• have a carbon-carbon double covalent bond
• one of the bonds breaks allowing another ethene molecule to add on
• repeated over and over to form a long chain

56
Q

Give similarities and differences between addition polymerisation and condensation polymerisation (5)

A

Similarities:
• both form a larger molecule
(S) Polvmerisation
Differences:
• condensation polvmerisation has different monomers
• addition polvmerisation has one type/same monomers
• condensation polymerisation produces one molecule of water or hydrogen
chloride ver ester link
• addition polvmerisation produces onlv one product
.addition polymerisation form ploy(alkene)

57
Q

Explain why alcohols are useful as solvents (3)

A

• alcohols dissolve many of the same substances as water
• give neutral solutions
• dissolve organic compounds

58
Q

Explain why methanol, ethanol and propanol are members of the same homologous series (3)

A

• same general formula/CH2n+OH
• same functional group/OH group/hydroxy group/hydroxyl group (do not
allow hydroxide)
• each formula is different by CH,
• similar physical properties/increases in boiling point as alcohol becomes
longer
• each alcohol reacts in similar ways each alcohol combusts completely to
produce carbon dioxide and water/similar chemical reactions

59
Q

Explain the trend in reactivity of methanol, ethanol and propanol with sodium (3)

A

• methanol is the most reactive
• propanol is the least reactive
• reactivity decreases as the carbon chain becomes longer

Chemistry (16 decks)

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