Chemistry IA Exemplar: Magnesium Salt Solubility and Crystallisation… | RevisionDojo

Loading document preview...

IB Chemistry HL Internal Assessment Example

How does the temperature of the water affect the solubilities of magnesium salts magnesium dichloride hexahydrate and magnesium nitrate hexahydrate, as measured by the crystallisation temperatures of the solution at manipulated concentrations?HL

Official IB Result

18/24

Criteria A: Research Design

5/6

Criteria Strands

A.1Research question context

Excellent

A.2Methodological considerations

Excellent

A.3Methodology description

Good

Criteria Feedback

Research question framed within a specific, real-world context of dietary magnesium supplements
Comprehensive methodological rationale, including control variables linked to scientific justifications
Responsive adaptations (e.g., switching to volumetric pipette, using bungs to prevent evaporation) to improve data quality
Detailed plan with sufficient trials and justification for concentration range

Procedure omits precise stirring rate, heating time, and thermometer reading intervals
Control of hot-water bath temperature not specified in enough detail
Minor repetition in research question wording impacting conciseness

1.1·Strength

Page 1• Click to view

The research question is framed within a specific context of dietary magnesium supplements, providing clear relevance and scope.

1.2·Weakness

Page 1• Click to view

The research question repeats terms unnecessarily; consider refining wording for conciseness and clarity.

1.3·Strength

Page 2• Click to view

The background effectively contextualizes magnesium’s physiological role and justifies investigating supplement solubility in varying water temperatures.

1.4·Strength

Page 2• Click to view

The rationale for selecting magnesium dichloride and nitrate hydrates over other salts is thorough, demonstrating sound methodological consideration.

1.5·Suggestion

Page 3• Click to view

Include quantitative values for

Δ H

and

Δ S

or reference literature sources to strengthen the Gibbs free energy analysis.

1.6·Suggestion

Page 4• Click to view

Clarify the precise rate and method of stirring during heating and cooling to improve reproducibility of crystallization observations.

1.7·Weakness

Page 5• Click to view

The description of the independent and dependent variables is clear, but control of the hot water bath temperature requires more detail (e.g., thermostat settings).

1.8·Suggestion

Page 6• Click to view

Consider using a volumetric flask for initial dilution steps to reduce cumulative pipetting uncertainties.

1.9·Weakness

Page 6• Click to view

The procedure omits specifics on stirring speed and duration; specify these to allow precise replication.

1.10·Strength

Page 7• Click to view

The controlled variables table systematically links each control to its scientific rationale, demonstrating comprehensive methodological consideration.

1.11·Strength

Page 8• Click to view

Adapting the concentration range mid-investigation shows responsiveness to preliminary data and optimizes the experimental design.

1.12·Strength

Page 8• Click to view

Implementing a volumetric pipette and using a bung to prevent evaporation illustrates thoughtful procedural refinements.

Criteria B: Data Analysis

5/6

Criteria Strands

B.1Communication of data recording and processing

Excellent

B.2Consideration of uncertainties

Good

B.3Data processing quality

Moderate

Criteria Feedback

Data tables and graphs are both clear and precise, with consistent units, labels, legends, and error bars
Comprehensive communication of data processing steps, including conversion of mass to moles and calculation of standard deviations
Appropriate consideration of uncertainties in measurements, with propagation into concentration and display in visualizations
Effective use of scatterplots showing all data points and fitted trendlines enhances interpretability

Uncertainty propagation is done additively rather than using quadrature methods
No justification provided for the polynomial order chosen in trendline fitting
Inconsistent formatting of unit notation (e.g., “moldm⁻3”)

2.1·Strength

Page 9• Click to view

The qualitative description of crystal formation and comparative solubility provides clear, precise communication of observed trends.

2.2·Weakness

Page 10• Click to view

The unit notation 'moldm⁻3' is inconsistently formatted; ensure consistent unit formats to maintain clarity.

2.3·Suggestion

Page 11• Click to view

Quantify uncertainties in molar mass or justify their omission to enhance transparency of uncertainty propagation.

2.4·Weakness

Page 12• Click to view

Uncertainties are combined additively rather than via quadrature; use correct propagation methods to improve accuracy.

2.5·Weakness

Page 13• Click to view

Combining percentage uncertainties by simple addition overestimates total uncertainty; consider quadrature for independent error sources.

2.6·Strength

Page 14• Click to view

Presenting all individual data points in scatterplots with error bars enhances precision and clarity in data visualization.

2.7·Weakness

Page 15• Click to view

Trendlines are applied without justification of polynomial order; include rationale or fit diagnostics (e.g.,

R^{2}

) to support the chosen model.

2.8·Strength

Page 17• Click to view

Calculating standard deviations using raw data demonstrates appropriate consideration of data variability and uncertainties.

Criteria C: Conclusion

4/6

Criteria Strands

C.1Conclusion relevance and support

Good

C.2Scientific context comparison

Moderate

Criteria Feedback

Conclusion directly answers the research question and is fully consistent with observed trends
Integration of thermodynamic reasoning (Le Chatelier’s principle, Gibbs free energy) to support findings
Acknowledgment of discrepancies with literature solubility values and attribution to systematic error

Lacks quantitative reference to uncertainty ranges when justifying the conclusion
Discussion of deviation magnitudes from literature is superficial and could be deepened
No exploration of future research directions to extend the investigation

3.1·Weakness

Page 18• Click to view

The comparison to literature solubilities identifies discrepancies, but the discussion remains superficial; deepen analysis of divergence magnitudes.

3.2·Weakness

Page 22• Click to view

The conclusion restates qualitative trends but lacks quantitative integration of uncertainty ranges; strengthen by referencing error margins.

3.3·Suggestion

Page 22• Click to view

Suggest outlining potential future research directions (e.g., other salt types or narrower temperature intervals) to extend the investigation’s scope.

Criteria D: Evaluation

4/6

Criteria Strands

D.1Methodological weaknesses

Good

D.2Suggested improvements

Moderate

Criteria Feedback

Specific methodological weaknesses are identified and linked to their impact on data accuracy
Realistic improvements are suggested for each limitation, demonstrating critical reflection
Use of an evaluation table shows systematic consideration of methodological issues

Some suggested improvements lack depth, feasibility discussion, or cost analysis
A few entries in the improvements table are incomplete or insufficiently explained
No quantification of the expected magnitude of improvement for each suggestion

4.1·Weakness

Page 19• Click to view

Several improvement cells are left blank or lack depth; provide realistic, detailed mitigation strategies and consider feasibility and resource constraints.

4.2·Strength

Page 19• Click to view

The evaluation section lists specific methodological limitations and links them to impacts on data, showing detailed critical reflection.

Loading scores...

Official IB Result

18/24

Criteria A: Research Design

5/6

Criteria Strands

A.1Research question context

Excellent

A.2Methodological considerations

Excellent

A.3Methodology description

Good

Criteria Feedback

Research question framed within a specific, real-world context of dietary magnesium supplements
Comprehensive methodological rationale, including control variables linked to scientific justifications
Responsive adaptations (e.g., switching to volumetric pipette, using bungs to prevent evaporation) to improve data quality
Detailed plan with sufficient trials and justification for concentration range

Procedure omits precise stirring rate, heating time, and thermometer reading intervals
Control of hot-water bath temperature not specified in enough detail
Minor repetition in research question wording impacting conciseness

1.1·Strength

Page 1• Click to view

The research question is framed within a specific context of dietary magnesium supplements, providing clear relevance and scope.

1.2·Weakness

Page 1• Click to view

The research question repeats terms unnecessarily; consider refining wording for conciseness and clarity.

1.3·Strength

Page 2• Click to view

The background effectively contextualizes magnesium’s physiological role and justifies investigating supplement solubility in varying water temperatures.

1.4·Strength

Page 2• Click to view

The rationale for selecting magnesium dichloride and nitrate hydrates over other salts is thorough, demonstrating sound methodological consideration.

1.5·Suggestion

Page 3• Click to view

Include quantitative values for

Δ H

and

Δ S

or reference literature sources to strengthen the Gibbs free energy analysis.

1.6·Suggestion

Page 4• Click to view

Clarify the precise rate and method of stirring during heating and cooling to improve reproducibility of crystallization observations.

1.7·Weakness

Page 5• Click to view

The description of the independent and dependent variables is clear, but control of the hot water bath temperature requires more detail (e.g., thermostat settings).

1.8·Suggestion

Page 6• Click to view

Consider using a volumetric flask for initial dilution steps to reduce cumulative pipetting uncertainties.

1.9·Weakness

Page 6• Click to view

The procedure omits specifics on stirring speed and duration; specify these to allow precise replication.

1.10·Strength

Page 7• Click to view

The controlled variables table systematically links each control to its scientific rationale, demonstrating comprehensive methodological consideration.

1.11·Strength

Page 8• Click to view

Adapting the concentration range mid-investigation shows responsiveness to preliminary data and optimizes the experimental design.

1.12·Strength

Page 8• Click to view

Implementing a volumetric pipette and using a bung to prevent evaporation illustrates thoughtful procedural refinements.

Criteria B: Data Analysis

5/6

Criteria Strands

B.1Communication of data recording and processing

Excellent

B.2Consideration of uncertainties

Good

B.3Data processing quality

Moderate

Criteria Feedback

Data tables and graphs are both clear and precise, with consistent units, labels, legends, and error bars
Comprehensive communication of data processing steps, including conversion of mass to moles and calculation of standard deviations
Appropriate consideration of uncertainties in measurements, with propagation into concentration and display in visualizations
Effective use of scatterplots showing all data points and fitted trendlines enhances interpretability

Uncertainty propagation is done additively rather than using quadrature methods
No justification provided for the polynomial order chosen in trendline fitting
Inconsistent formatting of unit notation (e.g., “moldm⁻3”)

2.1·Strength

Page 9• Click to view

The qualitative description of crystal formation and comparative solubility provides clear, precise communication of observed trends.

2.2·Weakness

Page 10• Click to view

The unit notation 'moldm⁻3' is inconsistently formatted; ensure consistent unit formats to maintain clarity.

2.3·Suggestion

Page 11• Click to view

Quantify uncertainties in molar mass or justify their omission to enhance transparency of uncertainty propagation.

2.4·Weakness

Page 12• Click to view

Uncertainties are combined additively rather than via quadrature; use correct propagation methods to improve accuracy.

2.5·Weakness

Page 13• Click to view

Combining percentage uncertainties by simple addition overestimates total uncertainty; consider quadrature for independent error sources.

2.6·Strength

Page 14• Click to view

Presenting all individual data points in scatterplots with error bars enhances precision and clarity in data visualization.

2.7·Weakness

Page 15• Click to view

Trendlines are applied without justification of polynomial order; include rationale or fit diagnostics (e.g.,

R^{2}

) to support the chosen model.

2.8·Strength

Page 17• Click to view

Calculating standard deviations using raw data demonstrates appropriate consideration of data variability and uncertainties.

Criteria C: Conclusion

4/6

Criteria Strands

C.1Conclusion relevance and support

Good

C.2Scientific context comparison

Moderate

Criteria Feedback

Conclusion directly answers the research question and is fully consistent with observed trends
Integration of thermodynamic reasoning (Le Chatelier’s principle, Gibbs free energy) to support findings
Acknowledgment of discrepancies with literature solubility values and attribution to systematic error

Lacks quantitative reference to uncertainty ranges when justifying the conclusion
Discussion of deviation magnitudes from literature is superficial and could be deepened
No exploration of future research directions to extend the investigation

3.1·Weakness

Page 18• Click to view

The comparison to literature solubilities identifies discrepancies, but the discussion remains superficial; deepen analysis of divergence magnitudes.

3.2·Weakness

Page 22• Click to view

The conclusion restates qualitative trends but lacks quantitative integration of uncertainty ranges; strengthen by referencing error margins.

3.3·Suggestion

Page 22• Click to view

Suggest outlining potential future research directions (e.g., other salt types or narrower temperature intervals) to extend the investigation’s scope.

Criteria D: Evaluation

4/6

Criteria Strands

D.1Methodological weaknesses

Good

D.2Suggested improvements

Moderate

Criteria Feedback

Specific methodological weaknesses are identified and linked to their impact on data accuracy
Realistic improvements are suggested for each limitation, demonstrating critical reflection
Use of an evaluation table shows systematic consideration of methodological issues

Some suggested improvements lack depth, feasibility discussion, or cost analysis
A few entries in the improvements table are incomplete or insufficiently explained
No quantification of the expected magnitude of improvement for each suggestion

4.1·Weakness

Page 19• Click to view

Several improvement cells are left blank or lack depth; provide realistic, detailed mitigation strategies and consider feasibility and resource constraints.

4.2·Strength

Page 19• Click to view

The evaluation section lists specific methodological limitations and links them to impacts on data, showing detailed critical reflection.