Question

9. The normal boiling point of methanol is 64.7⁰C and the molar enthalpy of vaporization if 71.8kJ/mol. The value of ΔS when 1.95 mol of CH₃OH(l) vaporizes at 64.7⁰C is

________ J/K

[A] 414 [B] 0.414 [C] 2.16 [D] 4.73 [E] 2.16

10. The normal boiling point of water is 100.0 °C and its molar enthalpy of vaporization is 40.67 kJ/mol. What is the change in entropy in the system in J/K when 22.1 grams of steam at 1 atm condenses to a liquid at the normal boiling point?

[A] -88.8 [B] -40.7 [C] 88.8 [D] 373 [E] -134

11. The normal boiling point of C₂Cl₃F₃ is 47.6 °C and its molar enthalpy of vaporization is 27.49 kJ/mol. What is the change in entropy in the system in J/K when 20.2 grams of C₂Cl₃F₃ vaporizes to a gas at the normal boiling point?

[A] 27.5 [B] -4.19 [C] 4.19 [D] 9.23 [E] -9.23

12. The thermodynamic quantity that expresses the extent of randomness in a system is __

[A] entropy [B] enthalpy [C] bond energy [D] heat flow [E] internal energy