Alkanes: Physical Properties
Your task
1. The table below shows some physical data (density and boiling point) for some alkanes.
Complete the table.
Alkane
Density (g cm-3)
Tb (K)
0.466
0.572
0.585
0.557
0.601
0.591
0.620
0.626
0.653
0.660
0.679
0.684
0.698
0.703
0.718
0.730
0.740
0.749
0.775
0.789
109.1
184.5
231.0
261.4
272.6
282.6
301.0
309.2
333.4
342.1
363.1
371.5
390.7
398.8
423.9
447.2
469.1
489.4
560.1
616.9
methane
ethane
propane
2-methylpropane
butane
2,2-dimethylpropane
2-methylbutane
pentane
2-methylpentane
hexane
2-methylhexane
heptane
2-methylheptane
octane
nonane
decane
undecane
dodecane
hexadecane
eicosane
Number of
carbon atoms
2. Plot a graph (or graphs) to show the way in which each physical property changes with increasing
number of carbon atoms. The number of carbon atoms should be on the horizontal axis.
Label any unusual points on your graph(s).
Now answer the following questions as fully as you can using information from your graph or
graphs.
3. How does the size of alkane molecule affect the density and the boiling point?
4. How does the shape of the alkane molecule affect these physical properties? Consider in turn:
•
•
•
straight chain alkanes;
single branch alkanes;
double branch alkanes.
Copyright © 2003 Nigel Saunders
N-ch3-04