IB Chemistry SL Internal Assessment Example

The question would be stronger if it named the concentration range directly. Stating the exact albumin and glucose levels in the research question would make the variables more operational and help the reader immediately see what is being tested.

The research question is framed in a specific biomedical context, linking calcium oxalate precipitation to albumin and glucose in synthetic urine. This gives the investigation a clear purpose and shows that the student has moved beyond a generic kidney-stone topic into a focused, relevant line of inquiry.

The student supports the design with literature on albumin’s role in calcium oxalate nucleation. This is effective because it shows the experiment is grounded in prior scientific work rather than personal intuition alone.

The inclusion of glucose literature alongside albumin helps justify why both variables were chosen. This strengthens the research design because the investigation is not treating the two factors as arbitrary additives; it shows a scientific basis for comparing them.

The independent variable is still described too broadly as “the amount of albumin and glucose added.” The methodology would be clearer if the student stated whether albumin and glucose were tested in separate series, or together in combined treatments, because that choice changes how the results should be interpreted.

The controlled-variable table is a useful start, but several key tolerances are still missing. The student should specify the permitted variation for temperature, pH, and reaction time so that another researcher can judge whether the conditions were actually held constant.

The pH adjustment method is still not reproducible enough. Saying to add HCl “while measuring pH” does not show how the end-point was decided, what instrument was used, or how the probe was calibrated, so the acidity level cannot be replicated with confidence.

If 5 mL of oxalate is added to 5 mL of synthetic urine, how does the student ensure that the stated albumin and glucose concentrations still apply in the final reaction mixture? Clarifying this would prevent confusion about whether the concentration refers to the stock solution or the mixed sample.

“Leave the filter paper containing the precipitate in a dry, ventilated area overnight” is too vague for full reproducibility. Drying should be defined by a fixed condition, such as a temperature or a constant-mass endpoint, because moisture left in the sample can inflate the measured precipitate mass.

The filtration step remains underspecified because the filter grade, pore size, and whether the paper was pre-weighed are not given. These details matter because they affect how much precipitate is retained and therefore whether masses from different trials are truly comparable.

Uncertainty is still not treated quantitatively in the results tables. The balance precision is given elsewhere, but the student does not show how that uncertainty affects the recorded masses or the mean values, so the reliability of the processed data remains unclear.

The student states the temperature and pH conditions used for the experiment, which helps the reader interpret the data in context. This is useful because those variables can strongly affect calcium oxalate precipitation and are therefore relevant to data interpretation.

The raw results are organised clearly into repeated trials and grouped by condition. This makes it possible to compare albumin concentrations directly and shows that the student collected enough data to identify a pattern rather than relying on a single measurement.

What would the trend look like if the student plotted the mean precipitate mass with error bars? That would help distinguish a real concentration effect from variation caused by the measurement process.

The glucose data show noticeable spread between trials, especially at the higher concentrations, yet no measure of variability is reported. The student should include a range or standard deviation so the reader can see whether the trend is stable or driven by anomalous trials.

The inclusion of a second results table in rounded form is useful because it helps the reader see the data at a glance. This is a good example of clear communication, provided the rounding is kept consistent with the raw values.

The graph communicates the general trend, but the processing is still not precise enough to be considered robust. A clear axis label with units and a visible link to the corresponding mean values would make the visual comparison much easier to verify.

The student does link the findings to published research, which strengthens the scientific relevance of the conclusion. This helps show that the observed trend is not isolated but sits within an established body of work on crystal formation.

How would the conclusion change if one or two of the high-glucose trials were treated as anomalous? Reflecting on this would help the student judge how stable the claimed glucose effect really is.

The student could make the conclusion more persuasive by adding a quantitative summary, such as the size of the change from the lowest to highest condition. A numerical comparison would show the scale of the effect, not just its direction.

The conclusion would be stronger if it briefly distinguished between what the data show and what the synthetic-urine model can safely claim about real kidney-stone formation. That distinction would prevent the argument from sounding more certain than the method supports.

The opening of the conclusion restates the investigation focus in a concise way, which helps the reader follow the logic from question to result to claim. This shows that the student understands the need for a conclusion to answer the research question explicitly.

The statement about “controlled conditions” is too general to fully support the conclusion. The student should identify which controls mattered most to the validity of the claim, because not all controls contribute equally to confidence in the final interpretation.

The conclusion is clearly tied to the findings: the student states that albumin reduced precipitation while glucose increased it. This is effective because the claims are directly matched to the direction of the recorded averages rather than being stated as a generic summary.