Clarification details
Updated March 2016. This document has been updated in its entirety.
This standard involves carrying out an investigation in chemistry involving quantitative analysis.
Carrying out an investigation
The investigation is based on an analytical technique such as titration or colorimetry. The titration may be acid-base or redox. If an acid-base titration is used, it must be a non 1:1 reaction unless it is a back titration.
A trend will usually involve continuous data, e.g. chloride ion concentration at increasing (measured) distances from the sea or vitamin C concentration in freshly squeezed orange juice over storage time.
A pattern will usually involve discontinuous data, e.g. calcium ion concentration in milk from cows grazing on different types of pasture, phosphate ion concentration in water bodies in urban and rural settings.
Consumer testing/quality control is not acceptable at this level, e.g. comparing the concentration of Vit. C of different fruit juices with the value stated by the manufacturer.
Students may work in groups during their investigation but assessors will need to ensure that each student has met the standard.
The report does not need to include details such as making standard solutions and raw data but this information should be presented in a log book.
Judgement made between Achievement, Merit and Excellence is based on the quality of the investigation. At Excellence there needs to be evidence of understanding of the chemistry principles involved in the investigation.
Making judgements
For all levels of achievement, students need to develop and carry out an investigation based on a possible trend or pattern. This involves producing a report which includes a purpose, a description of the procedure, a summary of the collected and processed data, and a conclusion based on the processed data.
Merit also requires students to control significant variables (including the standardisation of a solution or the student making a standard solution), accurate processing of data, and evidence of the mathematical steps used to process the data. The report needs to include a detailed method, a conclusion that links the processed data to the purpose, and an explanation of how the procedure resulted in the collection of quality data.
Excellence also requires students to use appropriate significant figures and units in their processing of the data. The report needs to include justification of the steps in the procedure to the relevant reaction(s) and to the nature of the samples being analysed.
A comprehensive evaluation of the investigation links the conclusion to chemical principles and/or real life applications and evaluates the reliability of the data or justifies how the processed data supports the conclusion.