SQA National 5 Chemistry skills of scientific inquiry and the assignment: a complete guide to planning, data, evaluation and the report

National 5 Chemistry tests more than recall: across both the question paper and the assignment, it assesses the skills of scientific inquiry, the scientific method of planning, gathering, processing, concluding and evaluating. This guide covers those skills and the structure of the 20 mark assignment report; each has its own key-area page with worked questions.

Planning and variables

Good planning starts with the variables:

• Independent variable: the one you deliberately change.
• Dependent variable: the one you measure to see the effect.
• Controlled variables: kept the same so the test is fair.

A fair test changes only the independent variable, so any change in the dependent variable can be linked only to it. For example, when investigating how concentration affects rate, the concentration is independent, the rate is dependent, and temperature and amount of solid are controlled.

Presenting data

• Tables need clear headings with units, the independent variable first.
• Line graphs (for continuous data) need both axes labelled with quantity and unit, a sensible scale, accurate points, and a best-fit line or curve.
• Bar charts are for data in categories.

Marks are routinely lost by missing units or a missing best-fit line, so treat presentation as carefully as the chemistry.

Processing the data

Processing means doing the calculations the data needs: average rate, the mole with $n = m / \text{GFM}$, concentration with $C = n / V$, or energy released with $E_h = cm\Delta T$. Always show working and give the unit with the answer. These are the same calculations drilled in the three content areas, reused on experimental data.

Drawing conclusions

A conclusion answers the aim and is supported by the evidence, quoting the trend in the data. "As the temperature increased, the rate increased, shown by the gas being collected faster at higher temperatures" is a strong conclusion; "temperature changes the rate" alone is not, because it does not use the evidence.

Evaluating reliability

An evaluation judges how good the experiment was:

• Repeat and take an average to improve reliability.
• Spot and discard outliers before averaging.
• Identify a real source of error (such as heat loss) and suggest a specific improvement.

A vague "be more careful" earns nothing; name the weakness and the fix.

The assignment

The assignment is the second course component, worth 20 marks out of 120, written as a report under controlled conditions. The candidate carries out an experiment with a chemical basis, gathers their own raw data and data from the literature, and writes the report. Its sections are:

• Aim: what is being investigated.
• Raw data: a correctly headed table with units.
• Processed results: calculations with working, and a labelled graph where appropriate.
• Analysis: the trend in the results.
• Conclusion: answers the aim, supported by the evidence.
• Evaluation: judges reliability and suggests an improvement.

Using both experimental and literature data lets the candidate compare their results with established values, strengthening the analysis.

How to secure the inquiry marks

1. Learn the three kinds of variable and be able to identify each in an unfamiliar experiment.
2. Always label tables and graph axes with units and draw a best-fit line.
3. Show working and units in every calculation.
4. Write conclusions that quote the evidence and evaluations that name a real fix.
5. For the assignment, work to the section structure and the mark scheme.

For the official course specification, visit sqa.org.uk and always revise from the current specification.