Question

Calculate the change in entropy that occurs in the system when 4.50 mol of diethyl ether (C4H10O) melts at its melting point (− 116.3 ∘C). ΔH∘fus=7.27kJ/mol

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Express your answer in joules per kelvin to three significant figures.

Answer 1

The equation for the change in entropy (ΔS) is given below:

where:

n - number of moles

ΔH⁰_fus - molar enthalpy of fusion

T - temperature (melting point)

Given:

n= 4.50 moles

ΔH⁰_fus = 7.27kJ/mol

T = − 116.3 ∘C = (-116.3 + 273.15)K = 156.8 K

Therefore the change in entropy that occurs in the system is:

Hence  the change in entropy that occurs in the system when 4.50 mol of diethyl ether melts at its melting point is 209 J/K