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Which ONE of the following compounds has the HIGHEST vapour pressure? A - 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 - NSC Physical Sciences - Question 1 - 2019 - Paper 2
Step 1
Identify the compounds and their properties
Answer
In this question, we need to evaluate the vapour pressures of four given compounds:
- HCOOH (Formic Acid) - Being a carboxylic acid, it has hydrogen bonds that reduce its vapour pressure.
- CH3CHO (Acetaldehyde) - An aldehyde that has some hydrogen bonding but is less than that of acids.
- CH3CH2OH (Ethanol) - Also a hydrogen-bonding alcohol but with more carbon atoms compared to Acetaldehyde.
- CH3CH2CH3 (Propane) - An alkane, which generally has higher vapour pressure than the others due to negligible hydrogen bonding.
Comparing these compounds, Propane is expected to have the highest vapour pressure due to its non-polar nature.
Step 2