Chemistry A-Level
absence as evidence
What absence as evidence means in Chemistry A-Level, as defined for AQA.
Definition of absence as evidence
Check what you remember
Read the wording for your board, then hide it and explain absence as evidence in your own words. Rough notes are fine. This is a self-check, with no mark or grade.
Reference: AQA
Deducing the functional group from the combination of peaks present and absent, since the absence of a second peak is what settles it.
Topics that use absence as evidence
- Infrared spectroscopy (AQA A-Level)
Related terms
- below 1500 cm⁻¹
- bond vibration
- broad O–H shapes
- C=O near 1700 cm⁻¹
- characteristic wavenumbers
- comparison with a database
- fingerprint region
- units of cm⁻¹
Using absence as evidence in the exam
Check the command word and mark scheme for your exact question. After comparing your explanation with the reference, use the term in an answer on the linked topic. This practice does not predict an exam mark.
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