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Chemistry IA Exemplar: Apple Juice Brand and Vitamin C Intake | RevisionDojo
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IB Chemistry HL Internal Assessment Example
Investigating How Apple Juice Brand Selection Affects Vitamin C Concentration Intake in Relation to Meeting Daily Nutritional Requirements
5
Official IB Result
14/24
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14/24
0
12
24
4.1·Question
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How would the research design change if the goal were to isolate vitamin C specifically rather than total titratable acidity? Thinking about this would help refine whether the chosen method truly matches the research question.
4.2·Suggestion
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The student could strengthen the context by adding one or two quantitative benchmarks from published juice studies, such as typical vitamin C concentrations in apple juice. That would make the comparison more scientifically grounded and help justify the expected scale of the results.
4.3·Weakness
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The background makes several broad health claims, but phrases such as “profound health benefits” and “several minerals” are not supported by specific compounds or data. The student should narrow the context to the exact chemical rationale for measuring vitamin C in apple juice, so the introduction supports the method more directly.
4.4·Weakness
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The statement that the juices were “stored at 22.5°C” is useful, but the method does not describe how that temperature was maintained or measured. The student should add the control procedure, because a condition cannot be reproduced reliably if only the target value is stated.
4.5·Question
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If the concentration differences between brands are smaller than the experimental uncertainty, how confident can the student be that the ranking is truly meaningful? Reflecting on this would improve the interpretation of the graph.
4.6·Suggestion
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The student could strengthen the evaluation by pairing each weakness with the direction of its effect on the result. For example, interference from other acids would likely inflate the calculated vitamin C concentration, which is important for judging validity.
4.7·Weakness
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The evaluation names several limitations but does not rank them by impact. The student should explain which error most strongly affected the final vitamin C values, because that would show a deeper understanding of reliability and validity.
4.8·Strength
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The improvement column is practical and experiment-specific, which shows that the student has thought about how to make the investigation better rather than simply listing flaws. That makes the evaluation useful and method-focused.
4.9·Weakness
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The discussion of improvements does not explain how much each change would reduce bias or uncertainty. Adding a brief estimate of impact would make the evaluation more analytical and help justify which fixes are worth prioritizing first.
4.10·Strength
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The evaluation identifies specific weaknesses rather than vague ones, including inconsistent swirling, interference from other acids, and parallax/meniscus issues. This is effective because each limitation is tied to a concrete part of the procedure.
4.11·Suggestion
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The improvement to use an iodine/redox titration would be more convincing if the student explained why that method better targets ascorbic acid. Linking the proposed change to the underlying chemistry would make the suggestion more analytical.
Criteria A: Research Design
4/6
0
3
6
Criteria Strands
Excellent
Research question context
Good
Methodological considerations
Good
Methodology description
Criteria Feedback
You framed the investigation in a clear and specific real-world context that made the question purposeful and relevant.
You included several methodological controls and enough procedural detail for another student to follow the main steps.
You showed thoughtful planning by using repeated trials and keeping key variables constant.
Some contextual claims were broader than the chemistry actually tested, which made the rationale feel slightly uneven.
A few procedural details were inconsistent, especially the indicator concentration, which weakens reproducibility.
The method would be stronger if it explained more clearly how the endpoint was standardized and how temperature was controlled.
The design does not fully account for the fact that apple juice contains acids other than vitamin C.
1.1·Strength
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The background successfully motivates why vitamin C matters by linking it to daily dietary requirements and consumer choice. That connection helps justify the investigation and shows why the measurements are relevant to an authentic health context.
1.2·Strength
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The research question is framed in a clear real-world context by naming the four brands, the purchase location, and the nutritional purpose of comparing vitamin C intake. This specificity gives the investigation a focused scope and makes the chemistry question meaningful rather than purely theoretical.
1.3·Strength
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The control variables table shows deliberate planning: the student identifies the sample volume, titrant concentration, and indicator use as factors that must be kept constant. This is good experimental thinking because it supports fair comparison across the four brands.
1.4·Weakness
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The design still treats the juice as if the only relevant acid were ascorbic acid, even though apple juice contains other acids that can also react during titration. The student should either justify this assumption carefully or redesign the method to account for total acidity versus vitamin C specifically.
1.5·Weakness
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The control table does not address how temperature was actually maintained at 22.5°C or how that condition was monitored. Because storage temperature can affect vitamin C stability, the student should explain the control method more explicitly to improve reproducibility.
1.6·Weakness
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The method does not explain key handling details such as whether the burette was rinsed with KOH, how air bubbles were removed, or how the initial reading was standardized. These omissions matter because they can change delivered volume and reduce reproducibility.
1.7·Weakness
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The indicator concentration is inconsistent across the submission: the equipment list references one concentration, while the procedure uses another. This inconsistency should be resolved, because the chosen indicator concentration affects endpoint appearance and therefore the comparability of trials.
1.8·Strength
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The preliminary KOH preparation is written in a clear sequence with measured mass, transfer steps, and solution-making logic. This level of procedural detail supports replication and shows that the solution concentration was intentionally prepared rather than assumed.
1.9·Suggestion
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The student could make the endpoint more reproducible by defining a standard stopping rule, such as a pale pink color lasting for a fixed time or using a white background. That would reduce dependence on subjective judgment during titration.
Criteria B: Data Analysis
3/6
0
3
6
Criteria Strands
Excellent
Communication of data recording and processing
Moderate
Consideration of uncertainties
Moderate
Data processing quality
Criteria Feedback
Your tables are generally clear, well organized, and easy to follow, with units and uncertainties shown in a sensible way.
You showed the processing steps from raw titres to averages and then to final calculated concentrations.
You explicitly calculated percentage uncertainty, which shows that you were thinking about measurement reliability rather than just reporting final numbers.
The chemical model used in the processing is oversimplified for this experiment, because juice contains other acids and vitamin C is not treated with full chemical accuracy.
The final concentration results are reported without propagated uncertainties.
The uncertainty treatment does not fully include all measured quantities, such as the sample volume measured with the graduated cylinder.
The graph would be stronger if it included error bars to show variation more clearly.
2.1·Strength
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The raw data table records initial and final burette readings with units and uncertainty, which makes the measurement trail transparent. This is strong communication because the reader can see exactly how each titre was obtained before any processing occurs.
2.2·Strength
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The percentage uncertainty calculation is shown explicitly, including the formula and a worked example. This is a strong feature because it demonstrates the student’s reasoning rather than just presenting a final uncertainty value.
2.3·Strength
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The average volume table is clearly organized by brand and trial, and the processing path from repeated titres to a mean value is easy to follow. That structure is effective because it lets the reader verify how the final results were produced.
2.4·Weakness
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The uncertainty analysis uses burette uncertainty, but the 10 mL sample volume was measured with a graduated cylinder and its tolerance is not included. Because sample volume is part of the concentration calculation, omitting this uncertainty weakens the completeness of the analysis.
2.5·Weakness
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The final concentration table gives values without propagated uncertainties, so the reader cannot see how measurement error affects the reported vitamin C concentrations. The student should include uncertainty on the final values to show the reliability of the processed data.
2.6·Suggestion
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The student should standardize the number of significant figures across processed values so the reported precision matches the measurement uncertainty. Consistent rounding would make the final data easier to compare and more scientifically defensible.
2.7·Weakness
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The processing assumes a direct C1V1=C2V2 relationship for vitamin C without addressing the chemical model behind that equation in this matrix. Because ascorbic acid is diprotic and apple juice contains other acids, this simplification introduces a significant processing inaccuracy.
2.8·Weakness
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Graph 1 communicates the final concentrations clearly, but it does not show error bars. Adding them would make the figure far more informative because the reader could immediately compare the size of variation relative to the differences between brands.
Criteria C: Conclusion
4/6
0
3
6
Criteria Strands
Excellent
Conclusion relevance and support
Moderate
Scientific context comparison
Criteria Feedback
You answered the research question directly and clearly by ranking the brands and restating the calculated values.
Your conclusion is consistent with the pattern in your processed data and is linked back to the comparison you made.
You made a real attempt to place the findings in a wider scientific context by referring to prior work and storage-related factors.
The comparison with scientific context stays fairly general and would be much stronger with specific published values.
Some explanatory claims are plausible but not tied closely enough to evidence from your own investigation.
The conclusion would be more balanced if it acknowledged the limitations of the titration model more explicitly.
3.1·Strength
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The discussion makes a genuine attempt to connect the results to scientific context by comparing the brands and considering storage-related explanations. That moves the conclusion beyond simple restatement and shows an effort to interpret the pattern.
3.2·Weakness
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The comparison to scientific context remains too general because it does not give published numerical values for vitamin C in apple juice. The student should include specific literature benchmarks so the conclusion can be judged against external evidence rather than only internal results.
3.3·Suggestion
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The conclusion could be stronger if it briefly acknowledged the titration model’s limitation in measuring total acidity rather than pure vitamin C. That would show a more balanced scientific judgment and improve credibility.
3.4·Weakness
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Claims about heat and light reducing vitamin C are reasonable, but they are not connected to measured storage conditions or cited studies in a way that explains the observed data. The student should distinguish between plausible explanation and evidence-based comparison.
3.5·Strength
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The conclusion clearly answers the research question and restates the comparative ranking of the brands using the calculated concentrations. This works well because it ties the final judgment directly back to the processed results rather than giving a vague summary.
Criteria D: Evaluation
3/6
0
3
6
Criteria Strands
Good
Methodological weaknesses
Good
Suggested improvements
Criteria Feedback
You identified several relevant methodological limitations, including mixing consistency, parallax/meniscus issues, and interference from other acids.
Your suggested improvements are practical and realistic for this type of investigation.
You clearly show awareness that the method could be improved to produce more reliable results.
The evaluation would be stronger if you explained which limitations had the biggest effect on the outcome.
The improvements are described, but not in enough depth to show exactly how they would reduce error or bias.
Some weaknesses are listed, but their likely direction of effect on the results is not fully developed.
