Topic 11
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What is quantitative data?
Taken from measurements made in a lab and are associated with random errors
What is qualitative data?
Non numerical data taken from observations
What is the absolute uncertainty of analog equipment?
Half the smallest smallest scale of division
What is percentage uncertainty?
Absolute uncertainty/ uncertainty measured X 100
What are random errors?
Unpredictable changes in the experiment like changes in the environment and mis reading
How can random errors be reduced?
By conducting repeat trials and using precise apparatus
What are systematic errors?
A flaw in the experimental design or apparatus where the measured value is higher or lower than the actual value
What can systematic errors not be reduced by?
Repeating trials
How do you workout the propagation of uncertainties?
Work out the % uncertainty of each and add them together
What is the formula for % error?
%error = experimental - theoretical / theoretical X 100
What is IHD?
The degree of unsaturation ( unsaturated will have less H atoms and thus hydrogen deficient)
What can IHD determine?
The number of rings or multiple bonds in a molecule
What is the formula for IHD?
IHD = 2x+2-y / 2 x is the number of carbon atoms y is the number of H atoms
What does an IHD of 0 mean?
There are no double bonds or rings
What does an IHD of 1 mean?
One double bond or a ring structure
What does an IHD of 2 mean?
A triple bond
What do you if there is a nitrogen atom?
Add 1 to the n of carbons and the n. of H atoms
What is HNMR?
The typical proton chemical proton shift relative to TMS
What is HNMR?
The typical proton chemical proton shift relative to TMS
What do the number of peaks on HNMR data tell you?
The number of different chemical envirnoments
Infrared spectroscoppy
• Can be used to determine the structure of a molecule - look at the wave number and compare to data booklet ( table 26)
What does a strong intensity mean for the infrared data?
Strongly polar
What does a weak intensity mean for the infrared data?
Weakly polar
What can mass spec be used for?
Determine the Ar of an element and the structure of a compound