Assessment Report

Level 1 Chemistry 2021

Standards 90932  90933  90934

 

Part A: Commentary

Candidates overall were likely to be successful if they were aware that question parts may follow on from each other and be linked. Candidates should actively look for this connection and ensure they use examples or explain chemical knowledge relevant to the stated question. This may mean referring to previous parts of a question; if necessary, turning to previous pages in the booklet

Candidates need to unpack the requirements of the question making clear links to the chemistry involved, for example between observations and the type of chemical reaction taking place using the language of chemistry appropriately, ensuring the correct use of the key terms such as atoms, molecules, and ions.

Candidates should avoid repeating answers or addressing aspects not required by the question.

Part B: Report on Standards

90932:  Demonstrate understanding of aspects of carbon chemistry

Examination

Candidates were required to respond to all three questions. Questions one to three required candidates to apply their understanding of the structure, properties, production, uses, importance and effects of carbon and its chemistry. The questions covered the requirements of the 2021 assessment specification, which were to demonstrate understanding of aspects of carbon chemistry. Candidates were expected to apply their understanding of carbon chemistry including alkanes, alkenes and alcohols and provide balanced chemical equations where relevant.

Observations

Candidates should endeavour to address the points in the question clearly and not write repetitive

answers with content that is not required. Reading the questions carefully and explicitly linking answers back to the question was a common area where candidates could improve.

Candidates need to be able to make clear links and explanations between health and environmental effects from combustion reactions.

Candidates were able to identify some of the conditions needed to produce ethanol by fermentation. They need to read the question carefully, include all the conditions and explain why these conditions were necessary.

Intermolecular forces that exist between molecules were often mixed up by candidates for covalent bonds within molecules.

Using the language of chemistry appropriately is important, for example, when discussing attractions/boiling points the word ‘atom’ was often used instead of ‘molecule’. 

The diagram of the distillation tower in question three allowed candidates to identify different fractions. Candidates need to gain a better understanding of the full process, from the heating up of the crude oil into a vapour before it enters the distillation tower.

Some candidates were able to identify that polymerisation requires the breaking of a double bond, but others needed to have a better explanation linking the double bond to the carbon atoms in the carbon chain of the molecule.

Grade awarding

Candidates who were awarded Achievement commonly:

  • wrote clear and accurate structural formula
  • read the question carefully and used the specific compounds named in the questions and in the tables
  • stated advantages and disadvantages of using ethanol as a fuel but did not link the advantage or disadvantage to the effect on the environment for attainment at a higher level
  • described clear and simple health and environmental effects of combustion reactions in the correct questions but did not explain why
  • explained that boiling points are related to the strength of forces between molecules, but did not link this to the heat energy required
  • understood the difference between complete and incomplete combustion and could identify the products of these
  • explained solubility of alcohols/alkanes, but confused vocabulary, such as atoms vs molecules ,in their answers
  • explained the general idea behind fractional distillation but with limited understanding of the process, did not explicitly identify where methane, nonane and eicosane collect
  • identified the process of cracking/polymerisation and the products/reagents required for these.

Candidates whose work was assessed as Not Achieved commonly:

  • did not take enough care with their structures (e.g. untidy structures, missing bonds, atoms etc)
  • used molecular formula instead of structural formula
  • did not read the question carefully (e.g. did not use the specific compounds named in the questions)
  • interchanged the terms atom, molecule, ion incorrectly. Stated that OH was an atom and did not realise the OH is in fact an oxygen and hydrogen atom joined together
  • confused health and environmental effects of combustion reactions
  • did not recall that fermentation requires glucose/sugar
  • stated that polymerisation needs a 'double bond', but did not refer to it being connected to carbon atoms
  • did not use the arrow correctly in the flow diagram in Q3b(i) (transposed the first products)
  • referred to bonds between atoms breaking when an organic compound changes state from liquid to gas, rather than forces between the molecules
  • did not recall conditions for polymerisation or cracking, and confused fractional distillation with cracking.

Candidates who were awarded Achievement with Merit commonly:

  • did not explain that methanol has an oxygen atom in the molecule and therefore, uses less oxygen to burn and burns cleanly, or relate that methanol being made from natural gas is not the reason it burns cleanly
  • linked ethanol combustion to complete combustion, lack of soot production, and the effect on photosynthesis (or hydrocarbon combustion to incomplete combustion, soot production etc)
  • linked the short carbon chain of ethanol to less CO2 production than long chain hydrocarbons and linked this to an environmental effect such as ocean acidification or sea level rising via climate change
  • linked ethanol production to plants and the recycling of CO2 in a carbon neutral process as an advantage of ethanol as a fuel
  • explained the solubility of compounds with respect to their relative attractions with water molecules compared to the attractions between solute molecules
  • linked the boiling points of compounds to their molar mass/carbon chain length and therefore the strength of intermolecular forces, and the heat energy required to separate the molecules
  • explained what the process of fermentation was, and the conditions required for fermentation, however, did not read the question properly, and did not explain why the conditions were required. Some were good at explaining why some of the conditions were necessary but did not include/mention all of them; warmth, moisture, yeast, and anaerobic conditions.
  • wrote accurate, unbalanced formula equations for fermentation, combustion, and cracking
  • linked incomplete combustion to a lack of oxygen in a confined space
  • explained the effect of a product of incomplete combustion on human health
  • explained the process of polymerisation clearly, linking the C=C double bond breaking to the subsequent formation of C-C single bonds between adjacent monomers repeatedly to make a long chain.

Candidates who were awarded Achievement with Excellence commonly:

  • wrote a balanced symbol equation for fermentation, supporting their answer by stating all conditions for fermentation to occur with explanations for these conditions
  • clearly linked two advantages of using ethanol as a fuel to environmental reasons. Many candidates struggled to identify more than one advantage of using ethanol as a fuel and link appropriately to environmental rather than health effects
  • explained in detail the dangers of burning butane gas indoors in a confined space, and linked the confined space of a tent to incomplete combustion and two clear health effects supported with a balanced symbol equations for combustion
  • explained how solubility can be used to differentiate between alkanes and alcohols, with reference to strength of attractions within a compound, compared to between compound and water
  • discussed the temperature gradient in a distillation tower, indicating that temperature decreases as you move up tower. The distillation process was explained with reference to relationship between size of molecule, strength of intermolecular forces and boiling point. They then went on to explicitly link this to where the three compounds are collected
  • linked the fact that methane gas does not condense, as it is a very small molecule and therefore remains a gas. Candidates recognised that formation of polypropene requires C=C double bond to be broken, and that ethene is not a suitable monomer due to only having 2 C atoms.
  • explained the process, using the specific molecules in the question as examples, and not just a generalised answer.

 


90933:  Demonstrate understanding of aspects of selected elements

Examination

The examination required candidates to demonstrate understanding of aspects of selected elements.

This examination paper contained three questions and candidates were required to answer all three questions. These questions provided candidates the opportunity to demonstrate understanding of atomic structure and the organisation of the periodic table, and the properties and uses of selected metals, non‑metals, and non-metal compounds. Overall, the paper was well attempted by most candidates.

Observations

This was a very accessible paper for candidates. Candidate performance would be increased with a better understand of metal properties and alloying. Candidates lacking the confidence to write short concise answers and use diagrams to support their answers struggled. Writing accurate observations for observed reactions is challenging for many candidates and it is recommended that they prepare and practice using the correct language to describe these. 

Grade awarding

Candidates who were awarded Achievement commonly:

  • demonstrated understanding of atomic structure and ion formation
  • described properties of named elements
  • used chemical symbols to - accurately write formulae for compounds and complete unbalanced equations
  • wrote simple facts and isolated observations and did not develop these into explanations

Candidates whose work was assessed as Not Achieved commonly:

  • used chemical symbols accurately to write accurate formula for compounds and complete equations (unbalanced)
  • did not read questions carefully enough and subsequently did not answer the question being asked
  • did not accurately describe observations for the reaction scenarios used.

Candidates who were awarded Achievement with Merit commonly:

  • explained the formation of ions
  • used chemical symbols to complete balanced equations
  • explained the physical properties of carbon allotropes
  • accurately interpreted the resource material and questions being asked.

Candidates who were awarded Achievement with Excellence commonly:

  • wrote balanced equations
  • wrote comprehensive answers with reference to the question’s context
  • demonstrated sound understanding of the chemical and physical properties of the elements used in this exam paper.

 


 

90934:  Demonstrate understanding of aspects of chemical reactions

Examination

The examination required candidates to demonstrate an understanding of aspects of chemical reactions. Where applicable, chemical reactions can be explained using the concept of electron transfer as outlined in the assessment specifications. This examination paper contained three questions and candidates were required to answer all three questions. These questions provided candidates the opportunity to identify and explain a wide range of applicable chemical reactions and their observations. The information in the resource booklet provided relevant support for the questions in this examination.

An error in question one was compensated for in the marking schedule. 

Observations 

Candidates need to ensure they have a good grasp of the specific colours of the chemical species included in this standard to fully link observations to reactants and products. Being able to differentiate between reaction types (e.g. displacement, precipitation, combination etc) continues to be a key skill in being able to explain what is happening in a reaction. This includes understanding the differences between various reaction types. Candidates need to be able to not only state the type of reaction by supporting answers with observations that would be expected. Knowledge of various tests that can be conducted to confirm products or reactions was also an area in which a good level of understanding would support a candidate to a higher grade achievement.

Grade awarding

Candidates who were awarded Achievement commonly:

  • described some observations for particular chemical reactions
  • completed word equations for chemical reactions
  • stated the types of reaction that were occurring in various situations
  • described an observation that supported the classification of specific reaction types
  • identified which precipitates would form when specific solutions were mixed with use of the solubility rules
  • recognised whether a reaction had occurred or not based on the activity series
  • described tests for specific products of reaction.

Candidates whose work was assessed as Not Achieved commonly:

  • confused reaction types
  • confused the activity series order (typically reversing it)
  • stated the type of reaction occurring (not consistently however) but could not support this with any specific evidence as to why it was that particular type of reaction
  • did not describe expected observations in a given reaction in general terms, and could not link their observations to reactants/products
  • did state the type of reaction occurring, but could not support this with any specific observations
  • did not know simple laboratory tests and how to carry them out (e.g. gas tests).

Candidates who were awarded Achievement with Merit commonly:

  • linked observations to most of the species in a given chemical reaction
  • wrote unbalanced symbol equations (including ionic equations) for given chemical reactions
  • explained what type of reaction was occurring, with links to the reactants and products
  • explained reaction types with reference to the activity series and / or solubility rules to support their answer
  • used chemistry-specific vocabulary in explanations of the different reaction types (showing an in-depth understanding of them)
  • provided in-depth explanations (including observations) of how to carry out tests for the presence of specific chemical species after a reaction had occurred.

 Candidates who were awarded Achievement with Excellence commonly:

  • provided correctly balanced symbol equations (including ionic equations)
  • linked all observations to reactants and products for given reactions
  • fully justified types of chemical reactions that were occurring, with regards to particle type (e.g. ions, electron transfer) and solubility rules as appropriate
  • explained displacement in terms of both the activity series and electron transfer and relate this to all observations
  • used chemistry conventions and vocabulary in answers
  • comprehensively explained how to conduct common laboratory tests to confirm the presence of specific products (or reactants) across various reaction type (including observations made in carrying out tests).

 

Chemistry subject page

 

Previous years' reports

2020 (PDF, 204KB)

2019 (PDF, 116KB)

2018 (PDF, 134KB)

2017 (PDF, 49KB)

2016 (PDF, 221KB)

 
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