Topic 11 Measurement and data processing

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11.1 Quantitative and qualitative data

Understandings:
Qualitative data includes all non-numerical information obtained from observations not from measurement.
Quantitative data are obtained from measurements, and are always associated with random errors/uncertainties, determined by the apparatus, and by human limitations such as reaction times.

11.1 Absolute and percentage uncertainties

Applications and skills:
Record uncertainties in all measurements as a range (+) to an appropriate precision.

Calculating uncertainties worksheet
Calculating uncertainties worksheet answer key

11.1 Random and systematic errors

Understandings:
Experimental design and procedure usually lead to systematic errors in measurement, which cause a deviation in a particular direction.
Repeat trials and measurements will reduce random errors but not systematic errors.
Applications and skills:
Distinction between random errors and systematic errors.
Discussion of systematic errors in all experimental work, their impact on the results and how they can be reduced.

11.1 Propagation of uncertainties

Understandings:
Propagation of random errors in data processing shows the impact of the uncertainties on the final result.
Applications and skills:
Propagation of uncertainties in processed data, including the use of percentage uncertainties.

11.1 Percentage error

Applications and skills:
Calculation of percentage error when the experimental result can be compared with a theoretical or accepted result.

11.3 Index of hydrogen deficiency

Understandings:
The degree of unsaturation or index of hydrogen deficiency (IHD) can be used to determine from a molecular formula the number of rings or multiple bonds in a molecule.

11.3 Infrared spectroscopy

Understandings:
Mass spectrometry (MS), proton nuclear magnetic resonance spectroscopy (1H NMR) and infrared spectroscopy (IR) are techniques that can be used to help identify compounds and to determine their structure.
Applications and skills:
Deduction of information about the structural features of a compound from percentage composition data, MS, 1H NMR or IR.
Guidance:
The regions employed for each technique should be understood.
The operating principles are not required for any of these methods.

11.3 Mass spectrometry

11.3 Proton nuclear magnetic resonance spectroscopy (1H NMR)

11.3 1H NMR - how to determine number of peaks in NMR spectrum

In this video, I take a look at how to determine the number of peaks on a 1H NMR spectrum of an organic compound by looking at its structure formula. Note that I do not cover splitting of the peaks in this video as this covered in the HL part of the syllabus.