Concluding in Chemistry (DP IB Chemistry): Revision Note
Concluding in Chemistry
The conclusion is a brief, focused summary of the findings of your investigation.
Your goal is to provide a clear and concise answer to your research question, based only on the evidence from your data analysis.
A strong conclusion relates your specific findings back to broader scientific principles and compares them to accepted values.
Principles of concluding
Interpret processed data and analysis to draw and justify conclusions
Your conclusion must be justified by your data.
This is the most important rule.
Start your conclusion with a direct answer to your research question.
Use the trend you identified in your interpretation to make a definitive statement.
Include key processed data as evidence to support your statement, such as:
The final calculated concentration.
The gradient of your graph.
The experimental enthalpy change.
Never introduce new ideas or explanations in the conclusion.
It should only be a summary of what you have already analysed.
Relate the outcomes to the stated research question or hypothesis
You must explicitly state whether your results support or refute your initial hypothesis.
For example: "The data shows a positive linear correlation between concentration and rate, which supports the hypothesis."
If your results do not support your hypothesis, that is perfectly fine and does not mean your experiment has "failed".
It is a valid scientific finding, and you should state it clearly.
You can then suggest reasons for the discrepancy in your evaluation.
Compare the outcomes to the accepted scientific context
A high-level conclusion compares your experimental results to accepted literature values from the IB data booklet, textbooks, or other reliable sources.
This comparison allows you to comment on the accuracy of your outcome.
When making a comparison, you should:
State the literature value.
Cite your source (e.g., "IB Chemistry Data Booklet, 2025").
Quantify the difference, usually by calculating the percentage error.
Discuss the impact of uncertainties on the conclusions
Your propagated uncertainty determines the confidence you have in your final result.
You must comment on the significance of your uncertainty.
Compare your percentage uncertainty with your percentage error.
If the percentage error is larger than the percentage uncertainty:
This suggests that the deviation from the literature value is not just due to the limitations of your equipment (random error)
The error is likely due to significant systematic errors in your methodology.
If the literature value falls within the range of your experimental uncertainty:
You can conclude that your result is consistent with the accepted value, despite any errors.
For example, your result is 50 ± 5 kJ mol-1 and the true value is 53 kJ mol-1.
Worked Example
Research question:
"What is the enthalpy of neutralisation of hydrochloric acid and sodium hydroxide?"
Sample conclusion:
The results of this investigation show that the neutralisation reaction between hydrochloric acid and sodium hydroxide is exothermic.
The experimentally determined standard enthalpy of neutralisation was calculated to be -52.3 ± 1.5 kJ mol-1.
This supports the hypothesis that the reaction would release energy.
The accepted literature value for this reaction is -57.1 kJ mol-1 (IB Chemistry Data Booklet).
The experimental value is reasonably close to this, with a calculated percentage error of 8.4%.
The experimental uncertainty was calculated to be ±2.9%.
The percentage error is significantly larger than the percentage uncertainty.
This suggests that the main cause of the inaccuracy is systematic error in the methodology, rather than the limitations of the measuring instruments.
Worked Example
Research question:
"What is the relationship between the concentration of hydrochloric acid and the rate of its reaction with calcium carbonate?"
Sample conclusion:
The investigation found a positive, linear relationship between the concentration of HCl and the initial rate of reaction.
A graph of rate versus concentration produced a straight line of best fit that passed through the origin, with a coefficient of determination (R2) of 0.992.
This indicates that the rate of reaction is directly proportional to the concentration of HCl, which supports the hypothesis.
This finding is consistent with collision theory, which predicts that as the concentration of a reactant increases, the frequency of effective collisions also increases, leading to a faster reaction rate.
The results therefore suggest that the reaction is first-order with respect to [HCl].
Examiner Tips and Tricks
Be concise and direct.
A conclusion should be a short paragraph, not a long essay.
Get straight to the point and answer your research question.
Only conclude what your data shows.
Do not make claims that are not supported by your results.
If your data is inconclusive, you must state that.
Always include your final result with its uncertainty.
Stating the uncertainty is crucial for discussing the reliability and accuracy of your conclusion.
Quantify your comparison.
Don't just say your result was "close" to the literature value.
Calculate the percentage error to show how close it was.
This is a much more scientific approach.
Unlock more, it's free!
Did this page help you?
