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Which ONE of the following compounds has the HIGHEST vapour pressure? A - English General - NSC Physical Sciences - Question 1 - 2019 - Paper 2
Question 1
Which ONE of the following compounds has the HIGHEST vapour pressure? A. HCOOH B. CH3CHO C. CH3CH2OH D. CH3CH2CH3
Worked Solution & Example Answer:Which ONE of the following compounds has the HIGHEST vapour pressure? A - English General - NSC Physical Sciences - Question 1 - 2019 - Paper 2
Step 1
Evaluate the vapour pressures of each compound
Answer
To determine which compound has the highest vapour pressure, we must consider the intermolecular forces present in each compound:
- HCOOH (Formic acid): Contains hydrogen bonding due to its hydroxyl group, resulting in relatively strong intermolecular forces.
- CH3CHO (Acetaldehyde): Also exhibits some hydrogen bonding but is less effective than formic acid due to a less polar functional group.
- CH3CH2OH (Ethanol): Features strong hydrogen bonding as well but has a larger molecular structure than formic acid, leading to higher intermolecular forces.
- CH3CH2CH3 (Propane): A non-polar molecule with weak London dispersion forces, thus generally has a higher vapour pressure compared to polar molecules.
Conclusion: Among the given options, propanol (D) should exhibit the highest vapour pressure due to weaker intermolecular forces compared to the other compounds.