Best examples of chemistry lab report discussion examples for students

Strong examples of chemistry lab report discussion examples (and why they work)

The fastest way to understand what your instructor actually wants is to see realistic examples of chemistry lab report discussion examples and then reverse‑engineer them. Let’s walk through several common lab types you’ll see in high school, AP, and intro college chemistry.

Each example below includes:

• A short context for the lab
• A sample discussion paragraph (or two)
• A quick breakdown of what the student did well (and what you can copy)

Example of a titration discussion: Acid–base titration (standardizing NaOH)

Lab context: You prepared a standard solution of potassium hydrogen phthalate (KHP) and titrated it with NaOH to determine the exact molarity of the NaOH solution.

Sample discussion excerpt:

The experimentally determined molarity of the NaOH solution was 0.102 M, which is within 2.0% of the target value of 0.100 M. This relatively low percent error indicates that the standardization procedure was mostly accurate and that the KHP primary standard was weighed and dissolved correctly. The consistent endpoint volumes across three trials (24.36 mL, 24.41 mL, and 24.39 mL) also suggest good precision in the titration technique.

However, several systematic and random errors likely contributed to the small positive deviation from the expected NaOH concentration. Overshooting the phenolphthalein endpoint by even one drop would decrease the calculated molarity of KHP and therefore increase the calculated molarity of NaOH. In addition, incomplete drying of the KHP before weighing could have led to a lower actual mass of solute than recorded, again causing an overestimation of NaOH molarity. Future repetitions of this experiment should include oven‑drying the KHP and using a pH meter to detect the equivalence point more objectively. Overall, the data support the expected stoichiometric relationship between NaOH and KHP and demonstrate that titration is a reliable method for standardizing strong base solutions.

Why this works:

• States the main result in the first sentence.
• Compares to an expected/target value and reports percent error.
• Distinguishes between precision (similar volumes) and accuracy (percent error).
• Names specific sources of error and predicts how they affect the result.
• Ends by connecting back to the purpose of the lab.

When you look for examples of chemistry lab report discussion examples for titrations, this is the structure you want to imitate.

Example of a kinetics discussion: Rate law for iodination of acetone

Lab context: You measured the initial rate of reaction between acetone and iodine at different concentrations to determine the rate law and rate constant.

Sample discussion excerpt:

The experimental data support a rate law that is first order in acetone, first order in H⁺, and zero order in I₂: rate = k[acetone][H⁺]. Doubling the acetone concentration while holding [H⁺] and [I₂] constant approximately doubled the initial rate, and a similar trend was observed when [H⁺] was doubled. In contrast, changes in iodine concentration did not produce a consistent change in the reaction rate, suggesting that I₂ is not involved in the rate‑determining step. The calculated rate constant, k, averaged 1.1 × 10⁻⁴ s⁻¹ at 25 °C, which is in reasonable agreement with literature values reported for similar conditions.

Deviations between the experimental and literature rate constants can be explained by limitations in timing and mixing. Because the reaction begins as soon as the reactants are combined, any delay between mixing and starting the timer would cause the measured rate to appear smaller. In addition, the color change used to judge the disappearance of iodine is somewhat subjective and depends on the observer. Using a spectrophotometer to monitor absorbance at a specific wavelength would reduce this subjectivity and improve the consistency of the initial rate measurements. Despite these limitations, the overall trends in the data are consistent with the proposed mechanism in which protonation of acetone is involved in the slow, rate‑determining step.

Key takeaways you can reuse:

• Clearly states the rate law and ties it to observed trends.
• Mentions temperature and compares to literature values.
• Connects data patterns to a proposed mechanism.
• Suggests a realistic improvement (spectrophotometer) rather than vague “do better measurements” language.

This is one of the best examples of chemistry lab report discussion examples for kinetics because it shows how to argue for a mechanism using real numbers and patterns.

Example of an equilibrium discussion: Determining Kc for an iron–thiocyanate complex

Lab context: You formed the FeSCN²⁺ complex ion, measured absorbance, and used Beer’s Law to determine equilibrium concentrations and the equilibrium constant Kc.

Sample discussion excerpt:

The average experimental value of the equilibrium constant, Kc = 92 ± 8, falls within the range of 80–110 reported in introductory chemistry texts for the Fe³⁺ + SCN⁻ ⇌ FeSCN²⁺ system at room temperature. This agreement suggests that the calibration curve was reasonably accurate and that the assumption of negligible dilution during mixing was valid. The relatively small standard deviation among the Kc values for the five trials also indicates that the procedure was reproducible.

The primary limitation of this experiment was the assumption that only the FeSCN²⁺ complex absorbs significantly at the selected wavelength. Any side reactions or additional complexes with similar absorbance would artificially increase the calculated concentration of FeSCN²⁺ and therefore inflate the value of Kc. Small errors in volumetric glassware and pipetting technique could also shift the initial concentrations, further affecting the equilibrium calculation. To improve the reliability of the results, future work could include recording spectra over a broader wavelength range and performing a more detailed analysis of possible side complexes. Overall, the data support the predicted formation of a strongly favored complex, consistent with Le Châtelier’s principle and the observed intense red color of the solution.

Why this is a strong example:

• Reports Kc with uncertainty, not as a single magic number.
• References textbook/literature ranges instead of pretending the lab exists in a vacuum.
• Explains how specific assumptions (only one absorbing species) affect the result.
• Connects observations (red color) back to equilibrium concepts.

If you need examples of chemistry lab report discussion examples for equilibrium labs, notice how this one blends math, theory, and visual observations.

Example of a calorimetry discussion: Enthalpy of neutralization

Lab context: You mixed a strong acid and strong base in a coffee‑cup calorimeter and used the temperature change to calculate ΔHₙₑᵤₜ.

Sample discussion excerpt:

The experimentally determined enthalpy of neutralization for the reaction between 1.0 M HCl and 1.0 M NaOH was −54 kJ/mol, which is slightly less exothermic than the accepted value of approximately −57 kJ/mol for strong acid–strong base reactions at 25 °C. This 5% difference suggests that the calorimeter did not capture all of the heat released during the reaction. Heat loss to the surroundings and the assumption that the solution’s specific heat capacity equals that of pure water are likely contributors to this discrepancy.

Additional sources of error include incomplete mixing of the solutions and a small delay between combining the reactants and recording the maximum temperature. Both would cause the measured temperature change to be lower than the true value, leading to a less negative calculated enthalpy. Using a better‑insulated calorimeter and a temperature probe that records continuously would improve the accuracy of the measurement. Despite these limitations, the sign and magnitude of ΔHₙₑᵤₜ are consistent with the expected exothermic nature of acid–base neutralization and support the idea that the reaction primarily forms water and dissolved salt.

What you can copy from this example:

• Immediate comparison of experimental and accepted values.
• Quantitative percent difference.
• Clear link between direction of error (less exothermic) and likely causes (heat loss).
• Practical suggestions tied to specific weaknesses in the setup.

Among the best examples of chemistry lab report discussion examples for thermochemistry labs, this one shows exactly how to talk about heat loss without sounding vague.

Example of a reaction yield discussion: Synthesis of aspirin (acetylsalicylic acid)

Lab context: You synthesized aspirin from salicylic acid and acetic anhydride, then measured percent yield and assessed purity (often by melting point or simple tests).

Sample discussion excerpt:

The percent yield of acetylsalicylic acid was 68%, which is typical for a student‑level synthesis that involves multiple transfer and purification steps. The product’s melting point range of 131–134 °C is slightly lower and broader than the literature value of 135–136 °C, suggesting the presence of impurities, likely unreacted salicylic acid or residual acetic acid. These impurities would reduce the apparent purity of the product but do not fully explain the loss of yield.

Mechanical losses during filtration and transfer are the most probable causes of the reduced yield. Some product remained adhered to the filter paper and glassware, and small amounts were lost during recrystallization when hot solution was decanted. Incomplete reaction due to insufficient heating time or inadequate mixing could also leave some salicylic acid unreacted. To improve both yield and purity, future experiments could use vacuum filtration to recover more product and confirm reaction completion using thin‑layer chromatography. Overall, the data indicate that aspirin was successfully synthesized, but the procedure could be optimized to increase yield and purity.

Why this example works for synthesis labs:

• Talks about both yield and purity, not just one metric.
• Uses melting point as evidence, not decoration.
• Identifies realistic student‑level errors (product on filter paper, transfers).

If you’re searching for real examples of chemistry lab report discussion examples for organic or synthesis labs, this one hits the standard expectations instructors look for.

Example of a gas laws discussion: Molar volume of a gas

Lab context: You generated hydrogen gas by reacting a metal with acid, collected the gas over water, and used the data to estimate molar volume at STP.

Sample discussion excerpt:

The experimentally determined molar volume of hydrogen gas at STP was 22.9 L/mol, which is close to the theoretical value of 22.4 L/mol predicted by the ideal gas law. This 2.2% difference suggests that the corrections for water vapor pressure and non‑standard temperature and pressure were reasonably accurate. The linear relationship between moles of hydrogen produced and gas volume collected also supports the assumption that the gas behaved nearly ideally under the experimental conditions.

Sources of error include gas leakage from the collection apparatus and inaccurate reading of the gas volume due to parallax or incomplete leveling of the water levels inside and outside the gas collection tube. Any loss of hydrogen before measurement would decrease the measured volume and shift the calculated molar volume away from the accepted value. Additionally, assuming that the hydrogen gas was completely dry after correction for water vapor pressure may not be entirely valid. Using better‑sealed connections and digital pressure and temperature sensors would likely improve the accuracy of the molar volume determination.

What to notice here:

• Connects the result directly to the ideal gas law.
• Mentions water vapor pressure, a detail instructors care about.
• Explains how each error would change the result, not just listing issues.

This is a strong example of how to write a discussion when gas collection and the ideal gas law are involved.

Example of a spectroscopy discussion: Determining concentration using Beer’s Law

Lab context: You used a spectrophotometer to measure absorbance of a series of standard solutions, built a calibration curve, and determined the concentration of an unknown.

Sample discussion excerpt:

The calibration curve for the dye solutions showed a strong linear relationship between absorbance and concentration, with an R² value of 0.998, indicating that Beer’s Law was obeyed over the concentration range used. Using the line of best fit, A = 18.3C + 0.005, the concentration of the unknown solution was calculated to be 3.2 × 10⁻⁵ M. This value is consistent with the instructor‑provided reference range of (3.0–3.5) × 10⁻⁵ M, suggesting that both the preparation of standards and the spectrophotometer readings were reliable.

Small deviations from perfect linearity at the highest concentrations may be due to stray light or limitations of the detector at higher absorbance values. In addition, fingerprints or bubbles in the cuvette could alter the path of light and introduce random error into individual absorbance measurements. To reduce these effects, future experiments should include careful cleaning of cuvettes and possibly discarding data points with obvious experimental issues. Overall, the results confirm that Beer’s Law is a practical method for determining the concentration of colored solutions within a defined concentration range.

Why this is one of the best examples for Beer’s Law labs:

• Uses the calibration equation and R² value directly in the discussion.
• Compares the unknown’s concentration to a realistic reference range.
• Identifies specific instrument‑related issues, not generic “measurement error.”

When instructors talk about strong examples of chemistry lab report discussion examples for spectroscopy, they’re usually looking for this level of detail and interpretation.

How to model your own discussion section after these examples

Looking across these real examples of chemistry lab report discussion examples, a pattern emerges. Strong discussions almost always:

• Start with the main result. State your key value(s) clearly: molarity, Kc, ΔH, percent yield, rate constant, or molar volume.
• Compare to something. That might be a theoretical value, a literature value, a textbook range, or the instructor’s reference.
• Quantify the difference. Use percent error or percent difference instead of vague words like “close” or “far.” Basic percent error guidance is available in many university resources, such as NIST’s uncertainty guidelines.
• Explain patterns, not just numbers. Talk about trends in your data: linear relationships, first‑order vs second‑order behavior, or how doubling a concentration affects rate.
• Discuss limitations honestly. Mention realistic issues: heat loss, endpoint subjectivity, incomplete reactions, side reactions, leaks, or instrument limitations.
• Propose specific improvements. Better glassware, different indicators, more trials, automated timing, or more sensitive instruments.
• Connect back to theory. Link your findings to concepts from lecture or your textbook—Le Châtelier’s principle, Beer’s Law, the ideal gas law, or collision theory.

If you build your discussion around those moves, your writing will look very similar to the best examples of chemistry lab report discussion examples you see in top‑scoring reports.

2024–2025 trends: What instructors now expect in chemistry lab discussions

Chemistry teaching has changed in the last few years, and expectations for lab reports have changed with it. Looking at recent guidance from major universities and national organizations, a few trends stand out:

• More emphasis on error analysis and uncertainty. Instructors increasingly want you to talk about uncertainty, not just “human error.” Many departments now align with approaches similar to those described by the American Chemical Society (ACS) and NIST, even in intro courses.
• Data literacy and reproducibility. Since the pandemic, there’s been a stronger push to interpret data critically, not just report it. That means explaining why your data might differ from literature and what that says about the method’s reliability.
• Safety and ethics awareness. Some courses now ask you to mention safety or environmental considerations in your discussion, especially in synthesis labs and green chemistry modules. Groups like the ACS Committee on Chemical Safety publish guidelines that many departments follow.

If you want your report to stand out in 2024–2025, model it on these real examples of chemistry lab report discussion examples and make sure you:

• Interpret your data like a scientist, not just a student filling a template.
• Use current terminology from your course (e.g., uncertainty, systematic vs random error).
• Show that you understand both the chemistry and the limitations of the experiment.

FAQ: Short answers based on real examples

Q: Can I see more examples of short discussion sentences I can reuse?
Yes. Here are a few sentence starters inspired by the best examples of chemistry lab report discussion examples above:

• “The experimentally determined value of ___ was ___, which differs from the accepted value of ___ by ___.”
• “This percent error suggests that the procedure was reasonably accurate, but several limitations may explain the remaining discrepancy.”
• “The data support a ___‑order dependence on ___, because doubling ___ approximately ___ the rate.”
• “The observed trend is consistent with ___ principle/theory, which predicts that ___.”

Q: What is an example of a strong first sentence for a discussion section?
Try something like: “The experimentally determined equilibrium constant, Kc = 92 ± 8, agrees with the textbook range of 80–110, indicating that the FeSCN²⁺ complex was formed as expected under the conditions used.”

Q: How many limitations or errors should I mention?
Usually two to four specific limitations are enough. Copy what you see in these examples of chemistry lab report discussion examples: focus on issues that actually matter for your main result (endpoint detection, heat loss, leaks, incomplete reaction), not generic statements like “human error” or “we could have been more careful.”

Q: Do I always need to compare my data to a literature value?
If your lab manual, textbook, or instructor provides an accepted value or range, you should absolutely compare. If not, compare your trials to each other (precision), or compare your trend to theory (e.g., linear vs non‑linear behavior). The examples include both types.

Q: Can I use first person ("I” or “we") in my discussion?
Follow your instructor’s rules. Many modern lab courses now accept first person in discussions, especially in the U.S., but some still prefer passive voice. The structure and content from these examples of chemistry lab report discussion examples will work either way—you can easily switch “we determined” to “the data indicate” if needed.

If you model your writing on these best examples of chemistry lab report discussion examples, you’ll move from “I don’t know what to say” to sounding like someone who actually understands their data—and that’s exactly what your instructor is grading.