Clarification details
Updated December 2021. This document has been created to address issues that have arisen from moderation.
Achievement standard requirements
The standard involves planning an investigation into a substance present in a consumer product, carrying out the investigation to collect primary data, processing and interpreting the data, and reporting on the investigation. An outline of the titration procedure that allows learners to modify aspects of it should be provided.
The determination of the concentration of a substance requires evidence of using stoichiometric principles and the relationships n=m/M and n=cV.
Stoichiometric principles involves the use of mole ratios. At least one calculation involving a non one-to-one stoichiometric relationship needs to be included in the task.
Making judgements
For all levels of achievement, learners need to develop a plan to determine if the sample and/or procedure require modification. Learners then carry out the investigation to collect, record and process data (and calculate the concentration of a substance relevant to the investigation) to make a conclusion. Descriptions of how the significant variables (those that could have a substantial impact on the results) were controlled are also required.
Merit also requires learners to use the results from the trials to develop a valid plan to modify the sample and/or titration procedure. Learners then need to carry out the valid plan to collect, record and process quality data (accurately determining the concentration of the standard solution and the substance present in the consumer product) to make a valid conclusion. Explanations of how the control of variables improved the quality of the investigation are also required.
Excellence also requires learners to accurately determine the concentration (using relevant significant figures and units) of the substance in the consumer product. Furthermore, learners need to justify how the modifications to the consumer product and/or the titration procedure improved both the validity and accuracy of the investigation. This could include giving examples specific to the investigation carried out that justify how the modification resulted in an increase in accuracy and validity. Finally, an evaluation of the conclusion in relation to the consumer product is required.