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Chemistry IA Exemplar: Electrolysis Time and Copper Transfer | RevisionDojo
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IB Chemistry SL Internal Assessment Example
How does the electrolysis time (1 min, 2 min, 3 min, 4 min, 5 min) affect the amount of copper transferred onto a paper clip through electrolysis in a copper sulphate solution?SL
5
Official IB Result
15/24
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General feedback
15/24
0
12
24
5.1·Suggestion
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Risk assessment safety measures are clear; include mention of neutralization or disposal procedures for copper sulfate waste to complete the section.
5.2·Suggestion
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The ethical/environmental section mentions proper disposal but could reference specific waste protocols or regulatory guidelines.
Criteria A: Research Design
5/6
0
3
6
Criteria Strands
A.1Research question context
Excellent
A.2Methodological considerations
Excellent
A.3Methodology description
Good
Criteria Feedback
Clear, discipline-specific context for the research question linking electroplating to industrial applications
Thorough explanation of methodological controls (repeats, solution concentration, voltage, electrode spacing, mass balance precision)
Procedure and materials described well enough for reproducibility with only minor ambiguities
Introduction left incomplete in places, omitting some variable definitions
No explicit method for measuring or monitoring current during electrolysis
Temperature control entry is split across tables and lacks a clear control method
Ambiguity in how detached copper is recovered and massed (filter paper vs copper isolation)
1.1·Strength
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Strong contextual linkage between industrial electroplating and the electrolysis process provides a focused discipline-specific background.
1.2·Suggestion
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The research question clearly identifies the variables but could be refined to specify the form of copper measured (mass of copper deposited) for increased clarity.
1.3·Weakness
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The introduction ends mid-sentence, leaving out parameter definitions. Complete the paragraph to ensure full explanation of variables.
1.4·Suggestion
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Background on copper sulfate is descriptive, but adding the dissociation reaction in formal notation (e.g., \ceCuSO4−>Cu2++SO42−) would strengthen chemical accuracy.
1.5·Strength
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The rationale effectively ties the investigation to redox theory and practical applications, demonstrating relevance within the chemistry syllabus.
1.6·Suggestion
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The diagram is clear, but the text should explicitly reference “Diagram 1” when describing migration of ions for smoother integration.
1.7·Strength
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Correct representation of the cathode reduction half-reaction is presented and formatted clearly.
1.8·Weakness
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The sentence describing Faraday’s first law ends abruptly (“should also”). Complete this to articulate the proportional relationship fully.
1.9·Weakness
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Including filter paper mass in deposit calculations introduces ambiguity; specify whether copper mass is isolated or combined with filter paper.
1.10·Suggestion
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Procedure lists independent and dependent variables clearly; include a note on how current is measured or monitored to enhance reproducibility.
1.11·Weakness
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The temperature control entry in the controlled variables table is incomplete. Provide full explanation and control method for clarity.
1.12·Suggestion
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Materials list is thorough; noting instrument precision (e.g., voltmeter ±0.01 V, stopwatch ±0.1 s) would strengthen methodological transparency.
1.13·Suggestion
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Procedure step 2 describes wiring; explicitly state how polarity is verified and how current is monitored to avoid ambiguity.
Criteria B: Data Analysis
3/6
0
3
6
Criteria Strands
B.1Communication of data recording and processing
Good
B.2Consideration of uncertainties
Moderate
B.3Data processing quality
Good
Criteria Feedback
Data tables include units and uncertainties and a well-labelled scatter plot with best-fit line
Use of Pearson’s r-value and error bars demonstrates sound statistical treatment
Correct application of uncertainty propagation formula
Inconsistent reporting of balance uncertainty (±0.001 g vs. ±0.0001 g) and significant figures
Omissions in processing (missing entries for some time points) and incomplete uncertainty treatment for time and volume
Outlier‐removal criteria not defined and combined uncertainties not carried through to regression
2.1·Weakness
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Raw data table contains inconsistent significant figures (e.g., 0.346 vs 1.024). Standardize to ensure precision and clarity.
2.2·Suggestion
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The choice to exclude the second trial is noted, but the criteria for outlier removal should be defined and justified.
2.3·Weakness
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Average mass table lists uncertainty as ±0.0001 g, conflicting with earlier ±0.001 g. Ensure consistency in uncertainty reporting.
2.4·Suggestion
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Sample calculation rounds the average too early. Retain full precision in intermediate steps before final rounding.
2.5·Weakness
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Processed data table omits entries for 4 and 5 minutes. Ensure completeness of data presentation.
2.6·Strength
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Graph is well-constructed with clear data points, best-fit line, and error bars illustrating standard deviation.
2.7·Strength
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Use of the Pearson’s correlation coefficient (r = 0.976) effectively quantifies the strength of the linear relationship.
2.8·Strength
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The propagation formula is applied correctly, demonstrating clear understanding of combined uncertainties.
2.9·Weakness
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Uncertainty discussion omits time and volume uncertainties which could influence the propagated error in mass measurements.
Criteria C: Conclusion
4/6
0
3
6
Criteria Strands
C.1Conclusion relevance and support
Excellent
C.2Scientific context comparison
Good
Criteria Feedback
Conclusion directly references numerical results, r = 0.976, and relates findings to Faraday’s law
Discussion of an anomalous data point and link to industrial relevance strengthens relevance
No quantitative comparison with theoretical or literature values of copper mass
