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3.1 Define the term boiling point - NSC Physical Sciences - Question 3 - 2019 - Paper 2
Question 3
3.1 Define the term boiling point. 3.2 Give a reason why this is a fair comparison. The boiling points of compounds Q, R and S are given below (NOT necessarily in ... show full transcript
Worked Solution & Example Answer:3.1 Define the term boiling point - NSC Physical Sciences - Question 3 - 2019 - Paper 2
Step 1
Step 2
Give a reason why this is a fair comparison.
Answer
The comparison of boiling points of compounds Q, R, and S is fair because they are all alkanes, which are in the same homologous series. This means they possess similar molecular structures and comparable properties due to having the same type of intermolecular forces.
Step 3
Which ONE of the three boiling points is most likely the boiling point of compound R? Explain the answer.
Answer
The boiling point that is most likely corresponding to compound R is 55 °C. This can be reasoned by considering that compound R, being 3-methylpentane, is less branched and generally exhibits a higher boiling point than more branched isomers like Q and S, which have lower boiling points due to their spherical or compact structures.
Step 4
Which compound (P or T) will be present in a greater amount in the SYRINGE? Explain the answer.
Answer
Compound T (Pentan-1-ol) will be present in a greater amount in the syringe. This is because T has stronger intermolecular forces compared to compound P (Pentanal) due to hydrogen bonding, which increases its boiling point, meaning more T would vaporize less than P under the same conditions.
Step 5
Explain the answer to QUESTION 3.4.1 by referring to the TYPES and STRENGTHS of intermolecular forces.
Answer
Compound P exhibits dipole-dipole interactions, while compound T exhibits both dipole-dipole interactions and hydrogen bonding. Hydrogen bonds are stronger than dipole-dipole forces, so in a mixture, more of the compound with weaker intermolecular forces (P) will vaporize and be found in the syringe relative to T.