Displayed formulae
3 marks · EasyTable 1 shows the molecular formulae of some simple alcohols. Table 1
| Alcohol | Molecular Formula |
|---|---|
| Methanol | CH3OH |
| Ethanol | C2H5OH |
| Propanol | C3H7OH |
Name the functional group present in these alcohols.
State the number of carbon atoms in a molecule of propanol.
Draw the displayed formula for methanol.
Work this out on paper, then compare with the answer and worked solution below. With a free account you can submit written answers for marking.
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(a) -OH
(b) 3
(c) — · must show One carbon atom with four bonds, Three hydrogens on the carbon, Oxygen bonded to the carbon and a hydrogen
Common mistakes: Answering 'C=O' or 'alkene' for a(i); Incorrect carbon count in propanol for a(ii)
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Marking points
B1 (a) · 1 mark · Names the -OH (hydroxyl) functional group.
B2 (b) · 1 mark · Correctly states 3 carbon atoms in propanol.
B3 (c) · 1 mark · Draws the displayed formula for methanol: one carbon bonded to three hydrogens and one -OH group.
Worked solution
(a) The functional group in alcohols is the -OH group.
(b) In propanol (\ce{C3H7OH}\)), there are 3 carbon atoms.