IB Chemistry SL Internal Assessment Example

The research question wording (\

The background discussion describes reversible reactions well but lacks mention of ionic strength or activity coefficients, which can affect Kₑq in solution-based equilibria. Consider discussing or controlling ionic strength to strengthen methodological context.

The specified independent variable temperatures are clear, but details on equilibration times and ionic strength control are missing. Specify equilibration duration and how ionic strength will be maintained.

The procedure calibration step omits the specific wavelength (λₘₐₓ) used for absorbance measurements. State the wavelength and justify its selection.

Table 1 lists controlled variables but omits ionic strength, pH, and cuvette path length, which affect absorbance. Include methods to control or measure these to ensure reproducible calibration.

Table 2 mixes an inline example calculation and final concentrations in one cell, which obscures clarity. Present calculation steps separately or in a footnote, and tabulate only final concentration values.

Qualitative observations in Part 1 lack details on mixing order, timing, and lighting conditions, which affects reproducibility. Describe these conditions for consistent qualitative data.

Table 3 presents absorbance values without stating path length or calibration uncertainty. Include cuvette path length and uncertainty in absorbance to improve precision of data reporting.

Figure 2 shows a strong trend but lacks error bars on data points. Including error bars for absorbance replicates would visually communicate uncertainty.

The calibration curve equation is forced through the origin without reporting the y-intercept and its uncertainty. Fit with intercept or justify zero-intercept assumption.

Table 7’s equilibrium concentrations are reported to three significant figures without consistency in subtraction. Ensure correct significant figures based on instrument precision.

The ICE table calculation assumes initial concentrations without adjusting for total volume change. Calculate initial [Fe³⁺] and [SCN⁻] correctly by accounting for dilution.

Table 8 shows uncertainty for 10°C only. Propagate uncertainties for each temperature to provide a complete uncertainty analysis.

Uncertainty calculations list volumetric device errors but omit spectrophotometer precision. Include instrument error for absorbance measurements.

The text reports a negative coefficient of determination. R² cannot be negative; verify calculation and correct reporting.

The Kₑq values in Table 9 unexpectedly increase at 30°C relative to 20°C. Consider discussing this anomaly and potential causes (e.g., equilibrium not reached).

The conclusion restates trends but omits quantitative connection to the Van ’t Hoff slope. Relate the gradient of ln(Kₑq) vs 1/T to ΔH° for deeper justification.

Literature comparison uses only a single 20 °C reference. Broaden context by comparing experimental Kₑq across multiple temperatures or citing additional sources.

The strengths table is cluttered, mixing reasons and weaknesses in one layout. Separate strengths and weaknesses into distinct tables for clarity.

The strengths section effectively lists positives but lacks explanation of their relative impact on results. Discuss which strength most improved reliability.

Improvements are realistic but not ranked by potential impact. Explain which suggestion would most reduce uncertainty and why.

Table 11 slot is blank. Populate it with documented weaknesses and suggested improvements to fulfill the evaluation criterion.

The weaknesses section (5.2) is empty. Provide specific methodological weaknesses and their impacts to complete evaluation.