IB Chemistry SL Internal Assessment Example

The introduction title is clear but would benefit from anchoring the investigation in a real-world context, such as battery performance or corrosion prevention, to enhance relevance.

Consider previewing the scientific context (e.g. applications in electrochemical cells) earlier, before the formal background, to frame the study’s purpose.

The background omits a concise description of how the salt bridge maintains charge balance; adding this would strengthen the conceptual context.

Background section clearly explains oxidation and reduction half-reactions using balanced equations, which supports reader understanding.

The apparatus table omits mass or volume values for CaCl₂ and KCl, hindering reproducibility. Include complete quantities.

The research question is succinct and directly aligns with the aim to study ionic-radius effects on galvanic cell voltage.

The soak time for the filter-paper bridge is not specified, creating ambiguity in conductivity. Specify exact duration to improve reproducibility.

Procedure steps 1–3 are well sequenced and detailed, facilitating clear experimental setup.

Including setup images strengthens the report by visually clarifying the apparatus arrangement.

Photographs lack scale bars and component labels; adding annotations would improve clarity and reproducibility.

The dependent variable’s unit is listed as Å rather than volts. Correct units to V to maintain precision and avoid confusion.

Variables table clearly distinguishes independent, dependent, and controls, demonstrating thorough experimental planning.

Raw trial-by-trial voltage data are omitted in favor of averages. Including full datasets enhances transparency and error checking.

Beyond the ionic-radius plot, include error bars on the time vs. voltage graph to reflect measurement uncertainty across intervals.

Percentage uncertainties for ionic radii are presented without derivation; include propagation steps or reference to source instrumentation.

Label Table 2 explicitly as “Total ionic radii with propagated uncertainties” and briefly state the propagation formula used.

When reporting the regression, include the coefficient of determination (R²) to quantify the strength of the linear fit.

The CaCl₂ average voltage is mis-typed as 1.96 V in the deviation table, which is inconsistent with earlier data; verify and correct it.

The uncertainty-of-mean calculation using $\frac{\sigma }{\sqrt{n}}$ is correctly applied, demonstrating solid understanding of error propagation.

The ±0.01 Å uncertainty assigned to each ionic radius measurement needs justification—specify the database or instrument precision.

Theoretical cell voltage formula $E_{cell}^{\circ }=E_{cathode}^{\circ }-E_{anode}^{\circ }$ is correctly stated and applied with standard potentials.

The regression equation is misreported; include the full form $y=-0.0502x+1.2235$ to correctly represent slope and intercept.

An r-value of 0.6305 indicates moderate correlation; avoid overstating the strength of the linear relationship in the conclusion.

The conclusion effectively links smaller ionic radii to higher voltage and cites literature to support the trend.

Evaluation will be stronger by estimating how each methodological weakness quantitatively affects voltage measurements.

The methodology evaluation identifies specific weaknesses (dissolution, connections), aiding critical reflection.

Quantify how suggested improvements (e.g., overnight soaking) will reduce uncertainty or variability to deepen the evaluation.

The evaluation table pairs weaknesses with realistic improvements, demonstrating clear methodological reflection.

Future work on temperature effects is well-motivated; outline a detailed protocol (e.g., temperature control, calibration) to enhance planning.