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wise otter.Chemistry
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8873 / 2027
Data and Experimental Skills

Lesson 1 of 3

Read unfamiliar data

Select evidence and connect it to a chemical principle.

A-Level 8873, revised syllabus (2026-2027)

  • I can organise relevant information.Syllabus

    Syllabus 8873, B1. Organise relevant information

  • I can select what matters.Syllabus

    Syllabus 8873, B2. Select what matters

  • I can explain relationships.Syllabus

    Syllabus 8873, B5. Explain relationships

  • I can apply chemistry to unfamiliar situations.Syllabus

    Syllabus 8873, B6. Apply chemistry to unfamiliar situations

  • I can integrate knowledge.Syllabus

    Syllabus 8873, B7. Integrate knowledge

Read unfamiliar data with a purpose

Separate the question, the evidence and the chemistry that connects them.

Start with the quantity or claim the question asks you to establish. Then locate the relevant measurements, conditions and any new definitions in the stem. An unfamiliar substance name does not make its data unusable: use the supplied information together with a familiar idea such as conservation of atoms, collision frequency or intermolecular attraction.

From information to an answer
  1. Name the task

    For a calculation, identify the required quantity and unit. For an explanation, identify the observation that needs explaining.

  2. Select the evidence

    Extract the relevant rows, axes and conditions. Distinguish a measurement from a proposed explanation; do not use every number just because it is present.

  3. Connect a principle

    State the chemical relationship that makes the evidence relevant. Check that the comparison holds other important variables constant.

  4. State the result and its limit

    Give a numerical answer with units, or a conclusion supported by a specific comparison. State an assumption where the inference depends on it.

Worked exampleAssess a claim about a catalyst

Two runs use the same amount of reactant and the same temperature. Run A gives 40 cm3 of gas in 20 s; run B gives 40 cm3 in 50 s. Both eventually give 60 cm3. A report says: "A produces more product because it is faster."

Try it first. Then show the worked stepsHide the worked steps
  1. The time to reach the same volume is smaller for A: its average rate to 40 cm3 is 2.0 cm3 s-1, compared with 0.80 cm3 s-1 for B.
  2. The final volumes are the same under the same collection conditions, so these data do not show more final gaseous product in A.
  3. The evidence supports faster production, not a greater final amount. Identifying the cause as a catalyst also requires the stated experimental difference between the runs.
Answer

Compare rate using a time interval and final amount using the plateau. They answer different questions.

A useful explanation joins evidence and mechanism: "At the same temperature and reactant concentration, this catalyst gives a higher measured rate; it provides an alternative pathway with a lower activation energy." Merely repeating "the graph is higher" does not explain the chemistry.

Check your understanding

A table gives temperature, concentration, reaction time and the colour of the laboratory bench. Which data belong in an explanation of the rate trend?

  1. Temperature, concentration and reaction time, after checking which one was changed
  2. Every column, since the examiner put each one there to be used in the answer
  3. Reaction time alone, since rate is calculated from time and nothing else
Show the answer

Temperature, concentration and reaction time, after checking which one was changed

Use the variables that can affect rate, and find out which one was varied. Bench colour has no chemical role, so do not invent a link just because a detail is given.