Entropy
Chemistry ⇒ Thermochemistry and Energetics
Entropy starts at 12 and continues till grade 12.
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See sample questions for grade 12
A chemical reaction occurs at 298 K with ΔH = -100 kJ and ΔS = -200 J K-1. Calculate ΔSuniverse.
Calculate the entropy change when 1 mol of an ideal gas is heated from 300 K to 600 K at constant pressure. (Cp = 29 J mol-1 K-1)
Calculate the entropy change when 2.00 mol of an ideal gas expands isothermally and reversibly from 10.0 L to 20.0 L at 300 K. (R = 8.314 J mol-1 K-1)
Calculate the standard entropy change (ΔS°) for the reaction: C(s) + O2(g) → CO2(g), given S°[C(s)] = 6 J K-1 mol-1, S°[O2(g)] = 205 J K-1 mol-1, S°[CO2(g)] = 214 J K-1 mol-1.
Describe how entropy changes when a solid is dissolved in a solvent to form a solution.
Describe the relationship between entropy and the number of microstates (W) in a system.
Describe what happens to the entropy of the surroundings when an exothermic reaction occurs at constant temperature and pressure.
Explain the Second Law of Thermodynamics in terms of entropy.
Explain why gases have higher entropy than liquids and solids.
Explain why mixing two different gases at constant temperature and pressure increases the entropy of the system.
Explain why the dissolution of NaCl in water is accompanied by an increase in entropy.
For the reaction: N2(g) + 3H2(g) → 2NH3(g), predict the sign of ΔS.
If the entropy change (ΔS) for a reaction is negative, what does this indicate about the disorder of the system?
If the number of microstates available to a system increases, what happens to its entropy?
State the Third Law of Thermodynamics.
The entropy change for the reaction 2SO2(g) + O2(g) → 2SO3(g) is negative. Explain why.
The standard molar entropy of O2(g) at 298 K is 205 J K-1 mol-1. What is the entropy of 2 mol of O2(g) at this temperature?
A reaction has ΔH = +40 kJ mol-1 and ΔS = +100 J K-1 mol-1. At what minimum temperature (in K) will this reaction become spontaneous?
A sample of 1.00 mol of an ideal gas undergoes a reversible isothermal expansion from 5.00 L to 25.0 L at 400 K. Calculate the entropy change of the system. (R = 8.314 J mol-1 K-1)
Consider the following scenario: A gas is compressed isothermally and reversibly from 20.0 L to 5.00 L at 350 K. Calculate the entropy change of the system if 2.00 mol of the gas is used. (R = 8.314 J mol-1 K-1)
