DP Chemistry (last assessment 2024)

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Question 17N.2.hl.TZ0.5c

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Date November 2017 Marks available [Maximum mark: 2] Reference code 17N.2.hl.TZ0.5c
Level hl Paper 2 Time zone TZ0
Command term Suggest Question number c Adapted from N/A
c.
[Maximum mark: 2]
17N.2.hl.TZ0.5c

Ethane-1,2-diol, HOCH2CH2OH, reacts with thionyl chloride, SOCl2, according to the reaction below.

HOCH2CH2OH (l) + 2SOCl2 (l) → ClCH2CH2Cl (l) + 2SO2 (g) + 2HCl (g)

(c)

The standard free energy change, ΔGθ, for the above reaction is –103 kJ mol–1 at 298 K.

Suggest why ΔGθ has a large negative value considering the sign of ΔHθ in part (a).

[2]

Markscheme

«3 moles of» liquid to «4 moles of» gas

OR

«large» positive ΔS

OR

«large» increase in entropy

TΔS > ΔH «at the reaction temperature»

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