AS 91911 annotated exemplars

This annotated exemplar is intended for teacher use only. Annotated exemplars are extracts of student evidence, with commentary, that explain key parts of a standard. These help teachers make assessment judgements at the grade boundaries.

Download all exemplars and commentary [PDF, 1.3 MB]

TKI Chemistry assessment resources (external link)

For Excellence, the student needs to carry out a comprehensive investigation into chemical species present in a sample using qualitative analysis.

This involves justifying the identification of chemical species present by linking secondary data and chemical principles to the reactions occurring during the analysis and discussing the significance of an identified chemical species for people and/or the environment.

This student has made links between the secondary data and chemical principles to justify the identification of the species in the solution (1). They have also provided a limited discussion on the significance of copper ions for humans (2).

For a more secure Excellence, the student could provide further discussion of the significance of copper ions for humans and/or the environment. Since the concentration of copper ions in the sample is unknown, the significance of the copper ions could vary.

Further linking showing that if the concentration of copper ions is low, then it will have a minimal effect on people for a short exposure but could still have serious effects as continual exposure can lead to bioaccumulation (3).

For Merit, the student needs to carry out an in-depth investigation into chemical species present in a sample using qualitative analysis.

This involves explaining the identification of chemical species present by linking the primary data to the procedure, writing relevant equations to explain all the changes occurring during the identification procedure, and explaining the significance of an identified chemical species for people and/or the environment.

This student has linked the data to the procedure used (1), and written equations for all the changes that occurred (2). The learner has also made links between the presence of magnesium ions and the impact on people (3).

To reach Excellence, the student could justify the chemical species present by linking secondary data and chemical principles to the reactions. For example, the formation of the complex ion caused the precipitate to dissolve, since the metal cation from the precipitate formed the complex ion, which is soluble in the solution (4). Furthermore, linking the formation of the magnesium hydroxide precipitate to the solubility rules to justify the identification of the species (5).

For Merit, the student needs to carry out an in-depth investigation into chemical species present in a sample using qualitative analysis.

This involves explaining the identification of chemical species present by linking the primary data to the procedure, writing relevant equations to explain all the changes occurring during the identification procedure, and explaining the significance of an identified chemical species for people and/or the environment.

This student has identified the chemical compound (1) based on the collected data and the procedure used (2). The student has written the equations for all the changes that occurred (3), and given explanations of the significance of magnesium ions for the environment (4).

For a more secure Merit, the student could link all the primary data to the procedure to identify both species. For example, the addition of H2SO4 to a new sample of sample A results in no change to the solution, and this can be linked to the identification Mg2+ in the sample (5).

For Achieved, the student needs to carry out an investigation into chemical species present in a sample using qualitative analysis.

This involves collecting primary data using an identification procedure, identifying chemical species present by matching primary data to the procedure, linking the chemical species to the compound present in the sample, and describing the significance of an identified chemical species for people and/or the environment.

This student has collected data using the procedure (1), applied this to identify the compound present (2), and described the significance of citric acid for people and the environment (3).

To reach Merit, the student could write the relevant equations for all the changes that occurred in the identification process. For example, writing the correctly balanced equation for the addition of Lucas reagent (including water as a product), and the actual structural formulae of organic reactants and products (4).

For Achieved, the student needs to carry out an investigation into chemical species present in a sample using qualitative analysis.

This involves collecting primary data using an identification procedure, identifying chemical species present by matching primary data to the procedure, linking the chemical species to the compound present in the sample, and describing the significance of an identified chemical species for people and/or the environment.

This student has collected primary data and matched this to the identification procedure used to identify chemical species (1). They have also linked the chemical species to the compound present in the sample (2), and provided a weak description of the significance of glycerol (3).

For a more secure Achieved, the student could further describe the significance of glycerol for people and/or the environment.

or Achieved, the student needs to carry out an investigation into chemical species present in a sample using qualitative analysis.

This involves collecting primary data using an identification procedure, identifying chemical species present by matching primary data to the procedure, linking the chemical species to the compound present in the sample, and describing the significance of an identified chemical species for people and/or the environment.

This student has collected primary data and matched this to the identification procedure used to identify chemical species (1). The student has also described the significance of an identified species (2).

To reach Achieved, the student could use the procedure and the primary data to identify the compound present in the sample, CuSO4 (3).