3.1 Define the term boiling point - NSC Physical Sciences - Question 3 - 2023 - Paper 2
Question 3
3.1 Define the term boiling point.
3.2 Write down the conclusion that can be made for curve P.
3.3 Explain the answer to QUESTION 3.2 in terms of the structures of... show full transcript
Worked Solution & Example Answer:3.1 Define the term boiling point - NSC Physical Sciences - Question 3 - 2023 - Paper 2
Step 1
Define the term boiling point.
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Answer
The boiling point of a substance is the temperature at which its vapor pressure equals the atmospheric pressure. At this point, the liquid begins to change into gas, indicating a transition from the liquid phase to the gas phase.
Step 2
Write down the conclusion that can be made for curve P.
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Answer
Curve P represents carboxylic acids, which exhibit a strong relationship between molecular mass and boiling point, indicating that as the molecular mass increases, the boiling point increases.
Step 3
Explain the answer to QUESTION 3.2 in terms of the structures of the compounds.
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Answer
The relationship observed in curve P can be attributed to the presence of functional groups in carboxylic acids that enhance intermolecular forces, particularly hydrogen bonding. Higher molecular weight compounds generally have larger surfaces for intermolecular attractions.
Step 4
Which homologous series is represented by curve S?
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Answer
Curve S represents aldehydes.
Step 5
Explain the answer to QUESTION 3.4.1 by referring to the strength of intermolecular forces.
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Answer
Aldehydes exhibit weaker intermolecular forces compared to carboxylic acids due to the lack of sufficient hydrogen bonding sites, leading to lower boiling points at similar molecular masses.
Step 6
For curve R, write down the molecular mass of the compound with a boiling point of 97 °C.
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Answer
The molecular mass of the compound corresponding to a boiling point of 97 °C in curve R is 74 g·mol⁻¹.
Step 7
IUPAC name of the compound in QUESTION 3.5.1.
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Answer
The IUPAC name of the compound with a molecular mass of 74 g·mol⁻¹ and a boiling point of 97 °C is butanol.
Step 8
Explain the difference in these boiling points by referring to the structures of these compounds.
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Answer
The difference in boiling points between compounds A and B can be explained by the presence of hydrogen bonding sites in compound B, which leads to stronger intermolecular forces. Compound A, with a lower boiling point, has less extensive hydrogen bonding, resulting in a lower energy requirement to overcome these forces.
