IB Chemistry HL Internal Assessment Example

The caption for Figure A appears without the actual cell diagram; ensure the image is embedded so readers can see the experimental setup.

The introduction is verbose and includes general energy storage context; focus more tightly on the Daniell cell and Nernst equation derivation to streamline relevance.

The student effectively situates the research question within the context of electrochemical energy‐storage technologies and the Daniell cell, providing a clear justification for investigating zinc nitrate concentration’s effect on cell potential.

Background describes the Daniell cell but omits a reaction schematic; including a half-cell diagram would enhance clarity and aid reproducibility.

The Nernst equation introduction clearly defines each variable and cites sources, making the theoretical basis precise and contextually appropriate.

The free energy discussion is accurate but could be shortened to focus on how ΔG relates directly to cell potential under non-standard conditions.

Derivation of the Daniell cell’s Nernst equation is presented correctly. Ensure you reference any approximations (e.g. neglecting activity coefficients).

The independent variable concentrations cover several orders of magnitude but lack justification; explain why 2 M down to 0.002 M was chosen.

The control‐variable table is thorough but offers no rationale for salt‐bridge composition; justify choice of KNO₃ and its concentration.

The equipment list omits electrode dimensions (surface area geometry); specify dimensions so others can reproduce surface‐area effects.

The initial control‐variable table has empty cells, suggesting incomplete documentation; ensure each control is fully described.

Step 7 of serial dilution has a volume misprint ($½\; cm³$); clarify to avoid compounding concentration errors.

The pilot study description is clear but does not quantify how the 5-s interval improves uncertainty; include comparative data if possible.

Procedure step 3–6 describes electrode placement but omits the order of connection; specify sequence to minimize systematic bias.

Including the final dilution step ensures the full concentration series is covered, demonstrating thorough preparation.

Equation B is correct but omit or annotate units of R, F, and n in the equation display to improve precision.

The dependent‐variable description states average potential but omits how the multimeter resolution contributes to uncertainty; include instrument precision here.

The raw data table is detailed with uncertainties for each concentration and time point, demonstrating clear and precise data recording.

Qualitative observations mention consistent voltage and color but omit metrics (e.g. absorbance or pH). Consider quantifying color changes to support claims.

After Eq. 5, restate variable definitions (μ, V_E, n) immediately to reinforce understanding before proceeding.

Uncertainty calculation in Figure 1 is shown but lacks clear separation of temperature and concentration terms; annotate each component separately.

The method of combining instrument uncertainty by multiplication is incorrect; use standard error or propagation equations for uncertainties in repeated measures.

The mean‐average formula is correct, but the choice of n=12 measurements should be justified to support statistical robustness.

The mass‐uncertainty calculation uses excessive significant figures ($0.0080010888$); round to three significant figures to reflect measurement precision.

In the ΔE uncertainty equation, explicitly substitute ΔT and ΔQ values within the formula for transparency.

Correctly derived partial derivatives for ΔE/ΔT and ΔE/ΔQ provide a solid basis for uncertainty propagation.

The Table 4 caption is brief; clarify that “Uncertainty (%)” refers to theoretical cell potential uncertainty for each Q.

Table 4 presents theoretical uncertainties across concentrations clearly, enabling comparison of error magnitudes.

Uncertainties for 0.0002 M and 0.002 M are excessively large; consider excluding these outliers or discussing their impact to avoid skewed interpretation.

Graph 2 is well‐constructed but omits error bars on theoretical points; include error bars to reflect propagated uncertainties.

Graph 1 clearly shows a logarithmic trend between [Zn²⁺] and E, including trendline and proper axes labels enhances interpretation.

Restructure the conclusion section to lead with key findings, then discuss consistency with Nernst equation to improve narrative flow.

The conclusion effectively links observed R² values and literature support to justify the zinc‐concentration–potential relationship.

Mentioning R²=0.849 is good, but discuss its statistical significance and degrees of freedom for a more rigorous interpretation.

Separate the evaluation into clear “Strengths” and “Limitations” subsections and align each with specific methodological impacts.

The junction potential is discussed qualitatively; include a typical mV range (1–10 mV) and estimate its contribution to the vertical gap.

The evaluation correctly identifies electrode oxidation but could quantify its impact (e.g. % potential loss) for a more nuanced critique.

Quantify how averaging over one minute reduced voltage fluctuations (e.g., standard deviation before/after) to highlight this strength.

The improvement of separate standard solutions instead of serial dilution is well-targeted; consider also using gravimetric preparation to minimize volumetric errors.