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Chemistry IA3 Research Investigation Guide

A practical guide to the QCE Chemistry IA3 research investigation, including claim unpacking, research questions, secondary evidence, limitations and conclusions.

Updated 2026-05-13 ยท 3 min read

Chemistry IA3 research investigation guide

Chemistry IA3 is a secondary-evidence research investigation. You are not trying to collect new lab data. You are using published scientific evidence to evaluate a claim through a focused research question.

The strongest IA3 responses usually feel narrow. They do not try to solve a whole social, economic or environmental issue. They choose a piece of the claim that can be judged using Chemistry evidence.

Build the rationale from claim to question

A good rationale should form a chain:

  1. State the claim.
  2. Identify the Chemistry concepts inside the claim.
  3. Narrow the claim to a specific chemical relationship.
  4. Explain why that relationship matters.
  5. Write a research question that your evidence can answer.

If a word appears in your research question, it should be prepared in the rationale. For example, if the question names a fuel, material, pollutant, temperature range or chemical process, the rationale should explain why that choice is relevant.

Find evidence before locking the question

It is risky to write the perfect research question first and then discover that no useful data exists. Search for evidence early, then tighten the question around what credible sources can actually support.

Strong evidence often comes from:

  • peer-reviewed journal articles
  • university research
  • government or scientific agency reports
  • reputable science publications with transparent methods and data

For most IA3 topics, a small number of highly relevant sources is better than many weak sources. You need enough evidence to compare trends, but not so much that the analysis becomes shallow.

Analyse trends, not just sources

Analysis should focus on what the evidence shows. Describe patterns with data values where possible:

  • Does a concentration increase or decrease the measured outcome?
  • Does one material produce a higher yield, lower emission or stronger response?
  • Is the relationship linear, curved, threshold-based or inconsistent?
  • Do two sources agree, or does one contradict the other?

Then explain the pattern chemically. A graph is not analysis until you explain what the relationship means.

Evaluate evidence limitations

Source credibility matters, but IA3 evaluation needs more than "this article is reliable". You should explain how useful the evidence is for answering your research question.

Useful limitations include:

  • a study tested different conditions from your chosen context
  • the sample size or range of values was narrow
  • the evidence measured a related variable, not the exact variable in your question
  • a model simplified the chemical system
  • a source supported one part of the question but not another

After identifying the limitation, explain whether it weakens, narrows or qualifies your conclusion.

Improvements and extensions

Improvements make the current investigation stronger. They should directly address evidence limitations. For example, use evidence with a wider concentration range, compare studies under more similar conditions, or include a source that measures the exact dependent variable.

Extensions move to a related question under the broader claim. For example, if your research question evaluates one fuel emission, an extension might investigate another emission, a different fuel blend, lifecycle production data or another reaction condition.

Conclusion structure

A strong conclusion:

  • answers the research question directly
  • uses the most important processed evidence
  • acknowledges limitations without sounding uncertain about everything
  • links back to the original claim cautiously

The safest wording is precise. Do not claim that your evidence proves the entire claim if your investigation only evaluated one narrow chemical relationship.

Sources