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 the correct order). 55 °C 49.7 °C 68 °C 3.3 Which ONE of the three boiling points is most likely the boiling point of compound R? Explain the answer. 3.4 A mixture of equal amounts of P and T is placed in a flask and heated to a temperature below their boiling points. Assume that no reaction or condensation takes place. The vapour produced is collected in a syringe. 3.4.1 Which compound (P or T) will be present in a greater amount in the SYRINGE? Explain the answer. 3.4.2 Explain the answer to QUESTION 3.4.1 by referring to the TYPES and STRENGTHS of intermolecular forces.

NSC Physical Sciences Optical Phenomena and Properties of Materials: 3.1 Define the term boiling poin

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

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 or external pressure. At this temperature, the substance transitions from a liquid to a gas.

Step 2

Give a reason why this is a fair comparison.

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Answer

The compounds Q, R, and S are all alkanes, which belong to the same molecular family, meaning they have similar molecular structures. This allows for a fair comparison of their boiling points since they will have comparable intermolecular forces and chain lengths.

Step 3

Which ONE of the three boiling points is most likely the boiling point of compound R? Explain the answer.

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Answer

The boiling point of compound R is most likely 55 °C. This is because compound R (3-methylpentane) is less branched than compound Q (2,2-dimethylbutane) and has similar surface area properties to compound S (Hexane). As a result, it exhibits stronger intermolecular forces compared to Q and weaker than S.

Step 4

Which compound (P or T) will be present in a greater amount in the SYRINGE? Explain the answer.

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Answer

Compound T (Pentan-1-ol) will be present in a greater amount in the syringe. Pentan-1-ol has stronger hydrogen bonding due to the presence of the hydroxyl group (-OH) compared to compound P (Pentanal), which primarily exhibits dipole-dipole interactions. This means that more energy is required to vaporize pentanal than pentan-1-ol.

Step 5

Explain the answer to QUESTION 3.4.1 by referring to the TYPES and STRENGTHS of intermolecular forces.

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Answer

In the mixture, Pentan-1-ol (compound T) has stronger hydrogen bonding compared to Pentanal (compound P), which possesses weaker dipole-dipole forces. Therefore, less energy is required to overcome the intermolecular forces of Pentan-1-ol, resulting in its greater presence in the vapor phase collected in the syringe.

3.1 Define the term boiling point - NSC Physical Sciences - Question 3 - 2019 - Paper 2

Worked Solution & Example Answer:3.1 Define the term boiling point - NSC Physical Sciences - Question 3 - 2019 - Paper 2

Define the term boiling point.

Give a reason why this is a fair comparison.

Which ONE of the three boiling points is most likely the boiling point of compound R? Explain the answer.

Which compound (P or T) will be present in a greater amount in the SYRINGE? Explain the answer.

Explain the answer to QUESTION 3.4.1 by referring to the TYPES and STRENGTHS of intermolecular forces.

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