Prove it mark schemes 5.1.1.1 3

5.1.1.2

5.1.1.3

5.2.1.1 5.2.1.2

5.2.1.5

5.2.2.1 5.2.2.2

5.2.2.3

5.2.2.4

5.2.2.5

5.2.2.7 5.2.2.8

5.2.3.1 5.2.3.2

5.2.3.3

4.2.4.1

4.2.4.2

5.7.1.1

5.7.1.2

5.7.1.3

5.7.1.4

4.7.2.1 C6H14

4.7.2.3

4.7.3.1

4.7.3.2

5.8.1.1 5.8.1.2

4.8.3.1 4.8.3.2

4.8.3.3 4.8.3.4 4.8.3.5

4.8.3.6 4.8.3.7

5.3.1.1 5.3.1.2

5.3.2.1

NOTE: Question gives Mr of C as 14 not 12!

5.3.2.2

4.3.3.1

4.3.3.2

Spec Ref.

Mark scheme

CS 5.1.4.3 5.4.1.4

(HT)

Triple 4.4.1.3 4.4.1.4

carbon is above lead in the reactivity series } NOT for 1 mark

carbon is below aluminium in the reactivity series } OXIDE for 1 mark

(HT) carbon can remove oxygen from/reduce lead oxide or cannot remove oxygen from aluminium oxide not aluminium more reactive than lead for 1 mark

OR similar ideas in comparing bond strengths 3

CS 5.4.2.5

Triple

4.4.2.4

Red (accept orange)

Neutralisation H+ + OH- H2O CS

5.4.2.5 (HT)

Triple

4.4.2.6(HT)

C A D B 1

acidic 1

CS 5.4.3.1 5.4.3.2

Triple

4.4.3.1 4.4.3.2

CS 5.4.3.3 5.4.3.5

(HT)

Triple 4.4.3.3 4.4.3.5

(HT)

0 marks No relevant content. Level 1 (1–2 marks) A brief reason is given against extraction or for recycling. There is little scientific terminology used. Level 2 (3–4 marks) Some reasons are given with clear statements against extraction and or for recycling. Some scientific terminology is used Level 3 (5–6 marks) Several reasons are given with a detailed explanation against extraction and for recycling. Scientific terminology is used accurately

examples of chemistry points made in the response ignore uses and properties of aluminium. Comparative statements count for both methods extraction: • limited resources of aluminium oxide • higher temperatures required allow quoted temperatures eg extracted at 950°C • large amount of energy required • expensive • requires mining / quarrying • process takes longer / has more stages • produces more carbon dioxide / greenhouse gases recycling: • saves resources • cheaper to recycle • uses less energy • only needs to be melted allow quoted temperatures eg melted / recycled at 700°C • less electricity needs to be used • less effect on environment • example of effect on environment eg less destruction of habitats • avoids need for disposal / use of landfill • no need for quarrying • sustainable

[6]

CS

5.4.3.4 5.4.3.5

(HT)

Triple 4.4.3.4 4.4.3.5

(HT)

CS 5.9.1.1 5.9.1.2

any three described from:

• plants take in (CO2), accept photosynthesis uses (do not accept CO )

Triple

4.9.1.1 4.9.1.2

• converted to glucose / starch / carbohydrates ignore carbon compounds by itself • CO2 locked up in fossil fuels, accept coal / oil / natural gas / methane for fossil fuels • CO2 reacts with / dissolves (sea)water, accept ocean removes CO2

• producing hydrogencarbonates, accept carbonic acid • producing carbonates, accept named carbonates • marine animals use carbonates to make shells, do not accept bones • forms sedimentary rocks, accept limestone / chalk/marble, do not accept sediments alone

CS 5.9.1.3 5.9.1.4

Triple

4.9.1.3 4.9.1.4

Main changes • oxygen increased because plants / algae developed and used carbon dioxide for photosynthesis / growth producing oxygen; carbon dioxide decreased because of this • carbon dioxide decreased because oceans formed and dissolved / absorbed carbon dioxide; carbon dioxide became locked up in sedimentary / carbonate rocks and / or fossil fuels • oceans formed because the Earth / water vapour cooled and water vapour in the atmosphere condensed • continents formed because the Earth cooled forming a supercontinent / Pangaea which formed the separate continents • volcanoes reduced because the Earth cooled forming a crust. Other changes • nitrogen has formed because ammonia in the Earth’s early atmosphere reacted with oxygen / denitrifying bacteria.

6 CS

5.9.2.1 5.9.2.2

Triple

4.9.2.1

4.9.2.2

general increase in temperature caused by increase in greenhouse gases 1

any two human activities correctly linked to a named greenhouse gas e.g. increased burning of fossil fuels causes more carbon dioxide deforestation causes more carbon dioxide more cattle production causes more methane use of landfill causes more methane

2 CS

5.9.3.1 5.9.3.2

Triple

4.9.3.1 4.9.3.2

CS

5.10.1.2

water needs more / different processes 1

because it contains any two from: • more organic matter • more microbes

5.10.1.3

Triple 4.10.1.

2

4.10.1.3

• toxic chemicals or detergents 2

CS 5.10.1.4(HT)

Triple

4.10.1.4

(HT)

Answer includes linking between ideas, showing the consequence of either not recycling or the advantage of recycling. Answers such as less fossil fuel needed so less carbon dioxide produced or less carbon dioxide produced so less global warming examples of the points made in the response resources (recycling) conserves supplies of ores copper available for longer as (at present rate of use) copper ores will run out in about 35 years (recycling) conserves supplies of fossil fuels or energy less fuel used at a lower cost land pollution mining scars landscape or produces noise pollution mining destroys wildlife habitats (recycling) less need to mine ores / fossil fuels so less habitat destroyed or less scarring of landscape (recycling) less need to use landfill for waste atmospheric pollution burning fossil fuels produces carbon dioxide / greenhouse gas which (may) cause global warming or climate change extraction produces sulfur dioxide which causes acid rain which can kill trees / fish

6

CS 5.10.2.

1

Triple 4.10.2.

1

CS 5.10.2.

2

Triple 4.10.2.

2

(recycling) is used to conserve iron (ore) or energy or resources or minimise pollution or reduce the need to quarry allow reverse arguments.

1 (not reuse) because of damage, paint removal, rusting/corrosion, metal fatigue/weaker

1 (not landfill) because sites have limited space or loss of habitats allow to reduce the use of landfill

1

4.10.3.2

4.10.3.

3

4.10.4.

1

4.10.4.

2

CS 5.5.1.2

Triple

4.5.1.2

A

1 C

1

CS

5.5.1.3 (HT)

Triple

4.5.1.3 (HT)

products are at a lower energy level than reactants if candidate has drawn a profile for an endothermic reaction penalise first marking point only activation energy correctly drawn and labelled

1 ΔH correctly labelled

1 –93 (kJ per mole) correct answer with or without working gains 3 marks allow 2 marks for +93 kJ per mole

if any other answer is seen award up to 2 marks for any two of the steps below: bonds broken (614 + 193) = 807 (kJ) or (614 + 193 + (4 × 413)) = 2459(kJ) bonds formed (348 + 276 + 276) = 900(kJ) or 348 + (2 × 276) + (4 × 413) = 2552(kJ) bonds broken – bonds formed allow ecf for arithmetical errors

3 more energy is released when the bonds (in the products) are formed

1 than is needed to break the bonds (in the reactants)

1 if no other marks gained, allow 1 mark for energy released for bond making and energy used for bond breaking

4.5.2.2 using hydrogen saves petrol / diesel / crude oil allow crude oil is non-renewable ignore hydrogen is renewable 1 using hydrogen (in fuel cells) does not cause pollution accept no carbon dioxide produced allow less carbon dioxide produced allow hydrogen produces only water 1

Spec Ref.

Mark scheme

CS 5.6.1.1 5.6.1.2

Triple

4.6.1.1 4.6.1.2

CS

5.6.1.2

Triple 4.6.1.2

any two from:

• temperature (of the HCl) • mass or length of the magnesium • surface area of the magnesium • volume of HCl

(i) (a greater concentration has) more particles per unit volume

allow particles are closer together 1

therefore more collisions per unit time or more frequent collisions. 1

(ii) particles move faster allow particles have more (kinetic) energy 1

therefore more collisions per unit time or more frequent collisions 1

collisions more energetic (therefore more collisions have energy greater than the activation energy) or more productive collisions

1

CS 5.6.2.1 5.6.2.2 5.6.2.3

Triple 4.6.2.1 4.6.2.2 4.6.2.3

CS

5.6.2.6 (HT)

5.6.2.7 (HT)

0 marks No relevant content

Level 1 (1−2 marks)

Triple

4.6.2.6 (HT)

4.6.2.7 (HT)

At least one statement about the effect of a condition on either rate or yield.

Level 2 (3−4 marks) Correct statements about the effect of at least one condition on rate and yield.

Level 3 (5−6 marks) Correct statements about the effect of at least one condition on rate and yield and at least one correct statement about compromise conditions.

Examples of the points made in the response

Temperature • a higher temperature gives a lower yield • a higher temperature gives a faster rate

Pressure • a higher pressure gives a higher yield • increase in yield gets less as pressure increases • a higher pressure gives a faster rate • increase in rate increases as pressure increases

Catalyst • using a catalyst speeds up reaction • catalysts allow a lower temperature to be used and so save energy / reduce energy costs

Compromise • a higher pressure gives a greater yield but increases costs / (safety) risks • a high pressure gives a faster rate but increases costs / risks • a high temperature makes reaction faster but reduces yield • a catalyst makes reaction faster so a lower temperature can be used which will increase the yield

6