Paper 1 June 2023 Chemistry- AS level OCR Breadth in Chemistry Paper 1 June 2023 (Mark S, Exams of Chemistry

Download Paper 1 June 2023 Chemistry- AS level OCR Breadth in Chemistry Paper 1 June 2023 (Mark S and more Exams Chemistry in PDF only on Docsity!

Paper 1 June 2023 Chemistry- AS level OCR Breadth in Chemistry

Paper 1 June 2023 (Mark Scheme)

Alkanes

• First four alkanes are methane (CH4), Ethane (C2H6), Propane (C3H8), and Butane (C4H10)
• single Bonded Alkenes and Alkynes
• Contain double and triple bonds respectively. Alcohols
• contain Hydroxyl group (OH)
• suffix ol or hydroxy if a higher priority group is present
• Diols contain two hydroxyl groups.

• Geminal: 2 Hydroxyl groups on the same carbon
• Vicinal: on adjacent carbons Common Names for Ketones

• suffix one
• Acetone (dimethylketone; 2- propanone) ; smallest ketone; similar as the figure
• 2 pentanone (R= CH3CH2CH2) 3 - butene- 2 - one
• Naming ketones

• methylvinylketone Carboxylic Acids and Derivatives
• Contain both carbonyl group C=O and hydroxyl group (OH)
• most oxidized group that appear on the MCAT
• Suffix: Oic acid
• Methanoic acid (Formic Acid)
• Ethanoic acid (acetic acid)
• Propanoic Acid (Propanoic Acid) Ester
• Carboxylic acid derivative
• OH is replaced with OR, an alkoxy group Amides
• Carboxylic acid derivative
• OH is replaced with an amino group

Anhydrides

• Carboxylic acid derivative
• formed by dehydration of 2 carboxylic acids

• Symmetric = same acid
• asymmetric = two different acids
• cyclic = intramolecular reaction of a dicarboxylic acid Identify whether longhand notation or noble-gas notation was used in each case below. Potassium (K): 1s22s22p63s23p64s longhand notation Identify whether longhand notation or noble-gas notation was used in each case below. noble-gas notation Iron (Fe): [Ar]4s23d noble-gas notation Identify whether longhand notation or noble-gas notation was used in each case below. Argon (Ar): [Ne]3s23p noble-gas notation Identify whether longhand notation or noble-gas notation was used in each case below. Magnesium (Mg): 1s22s22p63s longhand notation

The breakdown of Assessment Objectives for GCSE (9-1) in Chemistry B: Assessment Objective AO1 Demonstrate knowledge and understanding of scientific ideas and scientific techniques and procedures. AO1.1 Demonstrate knowledge and understanding of scientific ideas. AO1.2 Demonstrate knowledge and understanding of scientific techniques and procedures. AO2 Apply knowledge and understanding of scientific ideas and scientific enquiry, techniques and procedures. AO2.1 Apply knowledge and understanding of scientific ideas. AO2.2 Apply knowledge and understanding of scientific enquiry, techniques and procedures. AO3 Analyse information and ideas to interpret and evaluate, make judgements and draw conclusions and develop and improve experimental procedures. AO3.1 Analyse information and ideas to interpret and evaluate. AO3.1a Analyse information and ideas to interpret. AO3.1b Analyse information and ideas to evaluate. AO3.2 Analyse information and ideas to make judgements and draw conclusions. AO3.2a Analyse information and ideas to make judgements. AO3.2b Analyse information and ideas to draw conclusions. AO3.3 Analyse information and ideas to develop and improve experimental procedures. AO3.3a Analyse information and ideas to develop experimental procedures. AO3.3b Analyse information and ideas to improve experimental procedures.

J258/01 Mark Scheme June 2023 Question Answer Marks

AO

element Guidance 1 (a) Potable water  1 1. (b) Any two from: Distillation  Water evaporated/boiled  (Water vapour) then condensed  2 1.2 IGNORE ‘distillation’ with incorrect detail IGNORE ‘water heated’ OR Any two from: Membrane filtration  Salty water forced through membrane at high pressure  Water molecules pass but dissolved salts don’t  IGNORE ‘filtration’ unqualified (c) (i) To kill micro-organisms/bacteria  1 1.1 ALLOW ‘remove bacteria’ ALLOW sterilises the water IGNORE ‘stop disease’ [too vague] Answer must be in terms of bacteria, microorganisms etc. [Allow germs] (ii) Toxic / poisonous  1 1.1 BOD taste I GNORE ‘harmful’ [too vague] / Cost

Question Answer Marks

AO

element Guidance (iii) 

Question Answer Marks

AO

element Guidance 2 (a) First check answer on answer line If answer = 0.02025/2.025 x 10 –^2 award 3 marks 40.5/2 ✓ = 20.25 ✓ (20.25 ÷ 1000) = 0.02025/2.025 x 10 –^2 ✓

2.2 x 2 1.

ALLOW 0.

ECF correct conversion of any stated mg to g (b) Labelled suitable container containing labelled water ✓ Labelled heat source below ✓ 2 3.3a IGNORE test tube as a container IGNORE clamps, gauzes etc IGNORE list of apparatus (c) (^) Calcium hydroxide ✓ 1 2. (d) (^) (LHS) silver ✓ 2 1.2 ALLOW ECF from another metal wrongly used for first mark repeated in second. (RHS) silver chloride AND nitrate ✓ 2. (e) Any three from: Greater sensitivity /can detect very small amounts of a substance ✓ 3 1.2 IGNORE cost / safety ALLOW reliable as an extra point Greater accuracy ✓ Greater speed /Data automatically recorded ✓ Can identify different elements in mixtures ✓

Question Answer Marks

AO

element Guidance 3 (a) (^) energy ✓ mining ✓ 2 2.2 ALLOW them in either slot (b) First check answer on answer line If answer = 72(%) award 3 marks 168 x 100/232 ✓ = 72.41. ..... ✓ = 72 (to 2 sf) ✓

2.2 x 2 1.2 ECF allow calculated answer to 2 sf. (c) 2 1. Rusting can be prevented … physical barrier ✓ Rusting is a form of corrosion. ✓ Rusting is a reduction reaction Rusting is caused by oxygen alone (d) 2 1. Iron forms coloured compounds ✓ Iron forms ions with more than one charge. (^) ✓ Iron has a low density Iron has a low melting point

Question Answer Marks

AO

element Guidance 4 (a) Zinc is below carbon and Aluminium is above carbon in the reactivity series ✓ (so) aluminium oxide cannot be displaced by carbon ORA ✓ 2 1.2 ie links all three reactivities MUST MENTION DISPLACEMENT (b) (i) 2 1.2 DO NOT ALLOW any other ticks – these contradict those already scored (ii) (^) gain ✓ atoms ✓

(c) (i) (^) energy is needed to melt/decompose aluminium oxide / energy is needed to provide the electricity ✓ 1 2.1 IGNORE cost IGNORE unqualified heating, must link to melting ALLOW difficult to break bonds / forces [so long as not in terms of molecular / intermolecular forces] (‘Energy to separate atoms etc’ not quite enough, we need why it needs that energy, i.e. forces.) (ii) Solution will contain positive aluminium and positive hydrogen ions (which compete) / aluminium more reactive than hydrogen (more stable) ✓ (and/so) hydrogen gas forms at the (cathode) (instead of aluminium metal) ✓ 2 3.1b ALLOW discussion of hydrogen or H+ Al3+^ ions move to the positive electrode Oxygen is also formed ✓ The aluminium oxide is molten … ions … move.

✓

The negative electrode is made of steel

Question Answer Marks

AO

element Guidance 5 (a) ✓✓ 4 2.1 Any two correct in melting point/conducting electricity columns = 1 mark All four correct in these columns = 2 marks (b) ✓✓ 2 2.1 (^) Any two correct = 1 mark All correct = 2 marks (c) 2 1. Formula Melting point Does it conduct electricity when molten? Does it conduct electricity when solid? Structure Magnesium oxide (MgO) (high) (yes) no (Giant) ionic ✓ Magnesium (Mg) (high) (yes) yes (^) Metallic ✓ Silicon dioxide (SiO 2 ) high no (no) (giant covalent) True False Chlorine and silicon dioxide have atoms joined by shared pairs of electrons

✓

Forces between chlorine molecules are strong (^) ✓ Bonds between silicon atoms and oxygen atoms are strong (^) ✓ Particles that conduct electricity Magnesium oxide Ions ✓ Magnesium (^) Electrons ✓

Question Answer Marks

AO

element Guidance 6 (a) ✓

(b) ✓✓✓ 3 1.1 Two correct = 1 mark Three correct = 2 marks True False^ Four correct = 3^ marks The proportion of greenhouse gases in the atmosphere has increased over the last 200 years

✓

The greenhouse effect is only caused by carbon dioxide and methane

✓

The Earth would be too hot to support life without the greenhouse effect

✓

Most scientists think that recent climate change can be explained by increased greenhouse gas emissions

✓

Question Answer Marks

AO

element Guidance 7 (a) (^) Nitrogen and oxygen in the air ✓ React at high temperature of the engine. ✓

(b) (i) (^) carbon dioxide ✓ carbon monoxide has gained oxygen ✓ 2 2.1 IGNORE ‘nitrogen and carbon dioxide’ ALLOW carbon has gained oxygen (ii) Any two from: Catalytic converter doesn’t remove ALL the gases (CO and NO) ✓ CO 2 /carbon dioxide is formed / not removed (which is a greenhouse gas) ✓ Doesn’t remove sulfur (dioxide) and/or other particulates ✓ 2 3.1b

(c) (i) Any three from: Petrol engines produce more carbon monoxide than nitrogen monoxide ✓ Petrol engines produce 3 times more CO than NO ✓ More CO produced than NO even with catalytic converter ✓ A catalytic converter decreases the concentration of both gases ✓ Any correct calculation ✓ 3 3.2b Conclusions must go beyond statements about numbers from the graph, they must be in context ‘the chart shows more CO than NO’ = 0 IGNORE statements about ‘nitrogen’ or ‘carbon’, must be about the oxides. References to gases refer to ‘polluting gases’ from the stem, so ‘Less gas is produced using the converter’ = 1 mark ‘Petrol engines produce 3 times more CO than NO’ as a stand-alone answer = 2 marks (ii) First check the answer on answer line If answer = 3/1 or 3 award 2 marks 840/280 ✓ = 3 / 1 or 3 ✓

(d) (^) N 2 O ✓ 1 1.2 DO NOT ALLOW superscript

Question Answer Marks

AO

element Guidance 8 (a) (^) O 2 ✓ 2 1. 2 SO 2 AND 2 SO 3 ✓ 2. (b) 2 1. Rate of forward reaction = rate of reverse reaction (^) ✓ The reaction stops when equilibrium is reached The reaction stops when there is 100% SO 2 There will always be some SO 2 present at equilibrium

✓

(c) (i) As the temperature rises, the percentage falls (AW, ORA) ✓ 1 3.1a ALLOW negative correlation ALLOW reversed causality answers (ii) (^) 90 ✓ 1 2.2 ALLOW 91 (iii) First check the answer on answer line If answer = 83±1 award 2 marks Percentage converted 17±1 ✓ Percentage remaining 100 – 17±1 = 83±1 ✓

ECF from percentage converted (iv) First check the answer on answer line 3 2. If answer = 50(%) award 3 marks Rearrangement % = SO 3 x 80/SO 2 ✓ Mark^ point^1 will^ be^ scored^ if^ mark^ point^2 is correct. % = 20 x 80/32 ✓ = 50(%) ✓

Question Answer Marks

AO

element Guidance 9 (a) low boiling/melting point / does not conduct electricity / poor heat conductor / low density / colourless / odourless ✓ 1 1.1 IGNORE non-metal / full outer shell ALLOW gas (at room temperature) / insulator (b) Argon has a full outer shell / has 8 electrons in the outer shell / has a stable electronic structure/arrangement ✓ Chlorine gains one electron (to give a full (outer) shell) ✓ 2 2.1 IGNORE argon does not gain/lose electrons IGNORE chlorine has 7 electrons in the outer shell alone / chlorine does not have a full outer shell / is missing an electron DO NOT ALLOW chlorine loses or gains electrons ALLOW chlorine needs to gain electrons (c) (i) ✓✓ 2 3.2a All 4 correct = 2 marks Any 2 correct = 1 mark (ii) (^) Sodium / potassium ✓ 1 3.2b ALLOW rubidium / caesium /francium IGNORE hydrogen/ Group II IGNORE fluorine (d) (^) 22 ✓ 1 1.2 ALLOW 21.

Question Answer Marks

AO

element Guidance 10 (a) (i) ✓

1 1.2 DO NOT ALLOW - OH

(ii) (^) Methanoic acid ✓ 1 1. (b) (^) 1 - 6.9 ✓ 1 1.1 ALLOW 0 (c) (i) (^) Carbon dioxide ✓ 1 1.2 ALLOW CO 2 DO NOT ALLOW CO^2 (ii) (^) Ca(HCOO) 2 ✓ 1 2.1 ALLOW correct formula in any attempt at an equation ALLOW CaH 2 C 2 O 4 / Ca(HCO 2 ) 2 / Ca2+(HCOO-) 2 (d) (^) Filtration/filter ✓ to remove calcium carbonate from the mixture ✓ 2 3.3b ALLOW filtration given in explanation but DO NOT ALLOW ‘filter to remove crystals’ (=0) IGNORE to remove solids/insoluble solids/excess substances Mark point 2 for identifying calcium carbonate as the impurity to be removed (e) (i) (^) Evaporation/evaporate (AW) ✓ 1 1.2 IGNORE filtration / boiling / heating / crystallisation / put in an oven

(ii) First check the answer on answer line If yield = 30(%) award 3 marks 20g of calcium carbonate gives 26g of calcium formate / actual yield for 10g is 3.9 g ✓ % = 7.8/26 x 100 or 3.9/13 x 100 ✓ = 30(%) ✓

ALLOW (2) for 60 ALLOW (2) for 0. ALLOW (1) for 0.

Annotations available in RM Assessor

Annotation Meaning Correct response Incorrect response Omission mark Benefit of doubt given Contradiction Rounding error Error in number of significant figures Error carried forward Level 1 Level 2 Level 3 Benefit of doubt not given Noted but no credit given Ignore

1. Abbreviations, annotations and conventions used in the detailed Mark Scheme (to include abbreviations and subject-specific conventions). Annotation Meaning / alternative and acceptable answers for the same marking point 🗸 Separates marking points DO NOT ALLOW Answers which are not worthy of credit IGNORE Statements which are irrelevant ALLOW Answers that can be accepted ( ) Words which are not essential to gain credit Underlined words must be present in answer to score a mark ECF (^) Error carried forward AW (^) Alternative wording ORA (^) Or reverse argument