DP Chemistry (first assessment 2025)

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Question 20N.1B.SL.TZ0.2a

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Date November 2020 Marks available [Maximum mark: 1] Reference code 20N.1B.SL.TZ0.2a
Level SL Paper 1B Time zone TZ0
Command term Identify Question number a Adapted from N/A
a.
[Maximum mark: 1]
20N.1B.SL.TZ0.2a
(a)

Identify the independent and dependent variables in this experiment.

[1]

Markscheme

Independent variable:
chain length OR number of carbon «atoms in alcohol»
AND
Dependent variable:
volume of NaOH OR Kc/equilibrium constant OR equilibrium concentration/moles of CH3COOH ✔

Examiners report

Well answered. Students mostly identified (alcohol) chain length as the independent variable and Kc at the dependent. For the latter [ethanoic acid] at equilibrium was another popular choice with some students neglecting to clarify "equilibrium" which was needed for the mark. This evidences an issue already identified in the Internal assessment that very often students only identify the processed variables. The proportion of students referring to volume of NaOH was too low for expectations.

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