Igcse Model Questions Vol1 2021 Chemistry Question 12

Practice objective / multiple choice question 12 from the 2021 Igcse Model Questions Vol1 Chemistry examination.

Igcse Model Questions Vol1 2021 Chemistry Objective / Multiple Choice Hard Difficulty
Question 12 IGCSE_MODEL_QUESTIONS_VOL1 • 2021 • CHEMISTRY • objective

In a step‑growth polymerisation, 0.200 mol of adipic acid (C₆H₁₀O₄, \(M=146.14\) g mol⁻¹) reacts with 0.200 mol of ethylene glycol (C₂H₆O₂, \(M=62.07\) g mol⁻¹). At equilibrium 85 % of the functional groups have reacted. (i) Determine the number‑average degree of polymerisation \(DP_n\) and the number‑average molecular weight \(M_n\) of the resulting polyester. (ii) Using the Mark-Houwink relation \([\eta]=K M^{a}\) with \(K=1.2\times10^{-4}\,\text{dL g}^{-1}\) and \(a=0.75\), estimate the intrinsic viscosity of the polymer.

Answer Options

A. DP_n≈5.0; M_n≈9.5×10² g mol⁻¹; [η]≈0.0200 dL g⁻¹
Correct Answer B. DP_n≈6.7; M_n≈1.27×10³ g mol⁻¹; [η]≈0.0255 dL g⁻¹
C. DP_n≈7.5; M_n≈1.40×10³ g mol⁻¹; [η]≈0.0280 dL g⁻¹
D. DP_n≈8.2; M_n≈1.55×10³ g mol⁻¹; [η]≈0.0300 dL g⁻¹
Correct Answer
B
Correct Option:
DP_n≈6.7; M_n≈1.27×10³ g mol⁻¹; [η]≈0.0255 dL g⁻¹

About This Question

This is Igcse Model Questions Vol1 2021 Chemistry Question 12. It is one of the objective questions from the 2021 Igcse Model Questions Vol1 Chemistry examination.

Difficulty level: Hard .

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