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Second and Third Laws of Thermodynamics

#### Q. Imagine you start with a pot of 54 g of water. The initial temperature of the pot and water is 100 °C. If you leave this pot in a room that has a constant temperature of 105 °C, the water will spontaneously boil and you will end up with all water vapor at 105 °C. E. What is the heat from the perspective of the surroundings? F. What is the entropy change for the surroundings?

Solved • Apr 21, 2020

Second and Third Laws of Thermodynamics

#### Q. Imagine you start with a pot of 54 g of water. The initial temperature of the pot and water is 100 °C. If you leave this pot in a room that has a constant temperature of 105 °C, the water will spontaneously boil and you will end up with all water vapor at 105 °C. C. What is the change in enthalpy for this process (in Joules)? D. What then is the change in entropy for the system? Hint: Process at constant temperature.

Solved • Apr 21, 2020

Second and Third Laws of Thermodynamics

#### Q. For the reactionN2(g) + 3H2(g) →2NH3(g)ΔH = −92.2 kJ and ΔS = −198.1 J/K. What is the minimum amount of heat that must be released to the surroundings at room temperature (25oC) in order for the reaction to be allowed by the second law of thermodynamics?a.33.2kJ b.92.2 kJ c.0kJ d.59.0 kJ e.29.2kJ

Solved • Apr 21, 2020

Second and Third Laws of Thermodynamics

#### Q. For the reaction 2 NH3(g) + 2 O2(g) → N2O(g) + 3 H2O(g) ΔH° = - 683.1 kJ and ΔS° = - 365.6 J/K The maximum amount of work that could be done when 2.29 moles of NH3(g) react at 251 K, 1 atm is ______ kJ. Assume that ΔH° and ΔS° are independent of temperature.

Solved • Apr 16, 2020

Second and Third Laws of Thermodynamics

#### Q. For the reaction P4O10(s) + 6 H2O(l) → 4 H3PO4 ΔG° = -4484 kJ and ΔS°=-16.3 J/K at 292 K and 1 atm. The maximum amount of work that could be done by this reaction when 2.10 moles of P4O10(s) react at standard conditions at this temperature is __________kJ.

Solved • Apr 16, 2020

Second and Third Laws of Thermodynamics

#### Q. The boiling point of a substance is defined as the temperature at which liquid and vapor coexist in equilibrium. Use the heat of vaporization (ΔHvap = 30.91 kJ/mol) and the entropy of vaporization [ΔSvap = 93.2 J/(K•mol)] to calculate the boiling point (°C) of liquid bromine. Express your answer using two significant figures.

Solved • Apr 9, 2020

Second and Third Laws of Thermodynamics

#### Q. Calculate the number of microstates that are accessible to 5.0 g of graphite. (S= 5.74 J/mol K)

Solved • Apr 4, 2020