Chemistry IA Exemplar: Acetylsalicylic Acid Synthesis Temperature… | RevisionDojo

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IB Chemistry SL Internal Assessment Example

How does the temperature (50.0,60.0,70.0,80.0,90.0 °C) of Acetylsalicylic acid synthesis from Salicylic Acid and Acetic anhydride affect its % yield and purity (determined by the Iron (III) Chloride test and the melting-point of the Acetylsalicylic acid crystals)?SL

Official IB Result

15/24

Criteria A: Research Design

5/6

Criteria Strands

A.1Research question context

Excellent

A.2Methodological considerations

Good

A.3Methodology description

Excellent

Criteria Feedback

Research question situated in a clear, specific chemical and industrial context
Comprehensive step-by-step procedure with quantities, safety notes and uncertainties that allows full replication
Justified choice of variables and controls, with rationale for repeats and precision considerations

Personal motivation lacks scientific literature rationale
Controlled-variable list is incomplete and cuts off mid-description
Purity assessment relies solely on qualitative tests rather than quantitative measures

1.1·Strength

Page 1• Click to view

The research question is situated within a clear chemical and industrial context (yield and purity via two tests across temperatures), demonstrating specific relevance.

1.2·Weakness

Page 2• Click to view

The personal motivation statement lacks scientific context and does not justify the importance of the investigation; consider replacing with a brief literature‐based rationale.

1.3·Suggestion

Page 3• Click to view

Purity assessment relies on qualitative colour and melting‐point proximity; consider incorporating quantitative techniques (e.g. UV–Vis) or titration for more precise purity measurement.

1.4·Weakness

Page 3• Click to view

The controlled‐variable list item is incomplete and cuts off mid‐sentence; clarify the concentration control description fully to avoid ambiguity.

1.5·Strength

Page 5• Click to view

The procedure outlines stepwise repetitions across temperatures and trials, allowing complete independent reproduction.

1.6·Strength

Page 6• Click to view

The safety table comprehensively lists hazards, precautions and disposal protocols, demonstrating robust methodological consideration.

Criteria B: Data Analysis

3/6

Criteria Strands

B.1Communication of data recording and processing

Good

B.2Consideration of uncertainties

Moderate

B.3Data processing quality

Moderate

Criteria Feedback

Data tables and graphs are generally clear, with headings, units, error bars and R² values
Qualitative observations (effervescence, smell, cloudiness) are well-described, adding context to quantitative data
Theoretical yield calculation is correctly executed, showing good stoichiometric understanding

Repeated identical watch-glass masses indicate data-entry errors
Calculations are sometimes poorly expressed or mis-typed (e.g. ‘500 %’ uncertainty) and formulas are missing
Uncertainties are not fully accounted for (many apparatus lack stated uncertainties; systematic sources like purity tests are omitted)

2.1·Weakness

Page 4• Click to view

Many items in the materials table lack stated uncertainties, limiting precise error analysis; add or justify uncertainty values for all apparatus.

2.2·Suggestion

Page 8• Click to view

Subjectivity in colour change during the Fe(III) test may bias purity assessment; consider using spectrophotometry or digital image analysis for objectivity.

2.3·Strength

Page 8• Click to view

Qualitative observations are clearly described (effervescence, smell, cloudiness), providing contextual insight before quantitative analysis.

2.4·Suggestion

Page 9• Click to view

Table headings lack clarity on control vs sample data (e.g. positive control label); add explicit column titles for ease of interpretation.

2.5·Suggestion

Page 9• Click to view

Raw melting-point data are tabulated but lack summary statistics; include means and standard deviations to convey central tendency and spread.

2.6·Weakness

Page 9• Click to view

Identical watch glass masses across all temperatures indicate a likely data-entry error; revisit raw measurements and correct the table entries.

2.7·Suggestion

Page 10• Click to view

The theoretical yield section omits clear stepwise presentation; format each calculation with separate equations, variable definitions and units.

2.8·Strength

Page 10• Click to view

The theoretical yield calculation is correctly executed and reflects strong stoichiometric understanding.

2.9·Weakness

Page 10• Click to view

The mean calculation is described inconsistently and mislabels units; revise the formula as

\overline{x} = \frac{\sum x _{i}}{n}

and ensure units align.

2.10·Suggestion

Page 11• Click to view

Selecting a polynomial fit purely to maximize R² risks overfitting; justify curve choice based on reaction kinetics or consider linear/exponential models.

2.11·Weakness

Page 11• Click to view

Typographical inconsistency in the temperature label '90 O' could mislead readers; correct this to '90.0' °C for uniformity.

2.12·Suggestion

Page 12• Click to view

Relying on R² alone to choose the best‐fit line overlooks theoretical plausibility; discuss whether linear or exponential kinetic models better describe the data.

2.13·Weakness

Page 12• Click to view

Error propagation for melting‐point deviations yields a uniform ±1 % without clear link to instrument error; explicitly show propagation from thermometer uncertainty.

2.14·Weakness

Page 13• Click to view

The reported 500 % uncertainty for 80 °C is clearly incorrect; recalculate each percentage uncertainty using

\frac{Δ x}{x} \times 100%

Criteria C: Conclusion

4/6

Criteria Strands

C.1Conclusion relevance and support

Good

C.2Scientific context comparison

Moderate

Criteria Feedback

Conclusion addresses yield and purity trends directly and links them to reaction kinetics and equilibrium
Comparison with published IJHSR data provides scientific context and validates the findings

Quantitative support is minimal—yields and uncertainties are not explicitly cited
Discussion of discrepancies with literature is brief and lacks depth

3.1·Suggestion

Page 14• Click to view

Comparison with published IJHSR data is valuable; deepen analysis by discussing potential sources of discrepancy and experimental bias.

3.2·Weakness

Page 15• Click to view

The conclusion accurately restates trends but omits quantitative uncertainty ranges; incorporate yields ± uncertainties to strengthen its support by data.

Criteria D: Evaluation

3/6

Criteria Strands

D.1Methodological weaknesses

Good

D.2Suggested improvements

Good

Criteria Feedback

Specific methodological weaknesses (sample mass, melting-point method, error bars) are clearly described
Realistic improvement suggestions (doubling mass, automatic melting‐point apparatus, extended recrystallisation) are relevant and linked to error reduction

The relative impact of each weakness is not quantified or rigorously analysed
Improvements lack quantitative justification (e.g., no calculation of error reduction)

4.1·Strength

Page 4• Click to view

The note on method development acknowledges adaptations and constraints, strengthening reproducibility and critical reflection.

4.2·Suggestion

Page 15• Click to view

Quantify how doubling sample mass would reduce relative uncertainty (e.g. from 1 % to ~0.7 %) to substantiate the improvement recommendation.

4.3·Suggestion

Page 16• Click to view

Error bars not intersecting trendlines suggests the fit may obscure uncertainty; include residual plots or confidence bands to visualise data variation.

Loading scores...

Official IB Result

15/24

Criteria A: Research Design

5/6

Criteria Strands

A.1Research question context

Excellent

A.2Methodological considerations

Good

A.3Methodology description

Excellent

Criteria Feedback

Research question situated in a clear, specific chemical and industrial context
Comprehensive step-by-step procedure with quantities, safety notes and uncertainties that allows full replication
Justified choice of variables and controls, with rationale for repeats and precision considerations

Personal motivation lacks scientific literature rationale
Controlled-variable list is incomplete and cuts off mid-description
Purity assessment relies solely on qualitative tests rather than quantitative measures

1.1·Strength

Page 1• Click to view

The research question is situated within a clear chemical and industrial context (yield and purity via two tests across temperatures), demonstrating specific relevance.

1.2·Weakness

Page 2• Click to view

The personal motivation statement lacks scientific context and does not justify the importance of the investigation; consider replacing with a brief literature‐based rationale.

1.3·Suggestion

Page 3• Click to view

Purity assessment relies on qualitative colour and melting‐point proximity; consider incorporating quantitative techniques (e.g. UV–Vis) or titration for more precise purity measurement.

1.4·Weakness

Page 3• Click to view

The controlled‐variable list item is incomplete and cuts off mid‐sentence; clarify the concentration control description fully to avoid ambiguity.

1.5·Strength

Page 5• Click to view

The procedure outlines stepwise repetitions across temperatures and trials, allowing complete independent reproduction.

1.6·Strength

Page 6• Click to view

The safety table comprehensively lists hazards, precautions and disposal protocols, demonstrating robust methodological consideration.

Criteria B: Data Analysis

3/6

Criteria Strands

B.1Communication of data recording and processing

Good

B.2Consideration of uncertainties

Moderate

B.3Data processing quality

Moderate

Criteria Feedback

Data tables and graphs are generally clear, with headings, units, error bars and R² values
Qualitative observations (effervescence, smell, cloudiness) are well-described, adding context to quantitative data
Theoretical yield calculation is correctly executed, showing good stoichiometric understanding

Repeated identical watch-glass masses indicate data-entry errors
Calculations are sometimes poorly expressed or mis-typed (e.g. ‘500 %’ uncertainty) and formulas are missing
Uncertainties are not fully accounted for (many apparatus lack stated uncertainties; systematic sources like purity tests are omitted)

2.1·Weakness

Page 4• Click to view

Many items in the materials table lack stated uncertainties, limiting precise error analysis; add or justify uncertainty values for all apparatus.

2.2·Suggestion

Page 8• Click to view

Subjectivity in colour change during the Fe(III) test may bias purity assessment; consider using spectrophotometry or digital image analysis for objectivity.

2.3·Strength

Page 8• Click to view

Qualitative observations are clearly described (effervescence, smell, cloudiness), providing contextual insight before quantitative analysis.

2.4·Suggestion

Page 9• Click to view

Table headings lack clarity on control vs sample data (e.g. positive control label); add explicit column titles for ease of interpretation.

2.5·Suggestion

Page 9• Click to view

Raw melting-point data are tabulated but lack summary statistics; include means and standard deviations to convey central tendency and spread.

2.6·Weakness

Page 9• Click to view

Identical watch glass masses across all temperatures indicate a likely data-entry error; revisit raw measurements and correct the table entries.

2.7·Suggestion

Page 10• Click to view

The theoretical yield section omits clear stepwise presentation; format each calculation with separate equations, variable definitions and units.

2.8·Strength

Page 10• Click to view

The theoretical yield calculation is correctly executed and reflects strong stoichiometric understanding.

2.9·Weakness

Page 10• Click to view

The mean calculation is described inconsistently and mislabels units; revise the formula as

\overline{x} = \frac{\sum x _{i}}{n}

and ensure units align.

2.10·Suggestion

Page 11• Click to view

Selecting a polynomial fit purely to maximize R² risks overfitting; justify curve choice based on reaction kinetics or consider linear/exponential models.

2.11·Weakness

Page 11• Click to view

Typographical inconsistency in the temperature label '90 O' could mislead readers; correct this to '90.0' °C for uniformity.

2.12·Suggestion

Page 12• Click to view

Relying on R² alone to choose the best‐fit line overlooks theoretical plausibility; discuss whether linear or exponential kinetic models better describe the data.

2.13·Weakness

Page 12• Click to view

Error propagation for melting‐point deviations yields a uniform ±1 % without clear link to instrument error; explicitly show propagation from thermometer uncertainty.

2.14·Weakness

Page 13• Click to view

The reported 500 % uncertainty for 80 °C is clearly incorrect; recalculate each percentage uncertainty using

\frac{Δ x}{x} \times 100%

Criteria C: Conclusion

4/6

Criteria Strands

C.1Conclusion relevance and support

Good

C.2Scientific context comparison

Moderate

Criteria Feedback

Conclusion addresses yield and purity trends directly and links them to reaction kinetics and equilibrium
Comparison with published IJHSR data provides scientific context and validates the findings

Quantitative support is minimal—yields and uncertainties are not explicitly cited
Discussion of discrepancies with literature is brief and lacks depth

3.1·Suggestion

Page 14• Click to view

Comparison with published IJHSR data is valuable; deepen analysis by discussing potential sources of discrepancy and experimental bias.

3.2·Weakness

Page 15• Click to view

The conclusion accurately restates trends but omits quantitative uncertainty ranges; incorporate yields ± uncertainties to strengthen its support by data.

Criteria D: Evaluation

3/6

Criteria Strands

D.1Methodological weaknesses

Good

D.2Suggested improvements

Good

Criteria Feedback

Specific methodological weaknesses (sample mass, melting-point method, error bars) are clearly described
Realistic improvement suggestions (doubling mass, automatic melting‐point apparatus, extended recrystallisation) are relevant and linked to error reduction

The relative impact of each weakness is not quantified or rigorously analysed
Improvements lack quantitative justification (e.g., no calculation of error reduction)

4.1·Strength

Page 4• Click to view

The note on method development acknowledges adaptations and constraints, strengthening reproducibility and critical reflection.

4.2·Suggestion

Page 15• Click to view

Quantify how doubling sample mass would reduce relative uncertainty (e.g. from 1 % to ~0.7 %) to substantiate the improvement recommendation.

4.3·Suggestion

Page 16• Click to view

Error bars not intersecting trendlines suggests the fit may obscure uncertainty; include residual plots or confidence bands to visualise data variation.