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The Haber Bosch Process is an industrial process for “fixing” nitrogen, shown b…

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Wize University Chemistry Textbook > Thermodynamics Part 2: (2nd Law-entropy, 3rd Law, Gibbs Free Energy, Spontaneity)

3rd Law of Thermodynamics

2 Activities

Wize University Chemistry Textbook > Thermodynamics Part 2: (2nd Law-entropy, 3rd Law, Gibbs Free Energy, Spontaneity)

Gibbs Free Energy + Spontaneity

4 Activities

The Haber Bosch Process is an industrial process for “fixing” nitrogen, shown below. This process produces around 500 million tons of ammonia every year.
ΔfG0(NH3)=−16.4 kJ/mol\Delta_fG^0(NH_3)=-16.4\ kJ/mol

3/2 H2(g)+1/2 N2(g)→NH3(g)\rm 3/2\ H_{2(g)}\quad+\quad 1/2\ N_{2(g)}\quad\overrightarrow{\hspace{1.5cm}}\quad NH_{3(g)}

CompoundN2(g)H2(g)NH3(g)S298K0(J K−1mol−1)191.5130.6192.3\begin{array}{|c|c|c|c|}\hline \\[-1.7ex]\rm Compound &\rm N_{2(g)} &\rm H_{2(g)} &\rm NH_{3(g)}\\[2.5pt]\hline \\[-1.7ex]S_{298K}^0 (J\ K^{-1}mol^{-1}) & 191.5 & 130.6 & 192.3\\[5pt]\hline \end{array}
a) Calculate the standard enthalpy of nitrogen fixation at 25oC (Answer in kJ/mol, to 3 sig. fig.)
b) Calculate the equilibrium constant for nitrogen fixation at 25oC (One decimal place)
c) Is this process spontaneous in the forward direction (True/False)
d) In the following list, select three things you could do to the system in order to favour production of NH3. (Use the numbers to indicate your answer in numerical order ie. 1 2 3)
1) Increase pressure of H2
2) Decrease pressure of N2
3) Remove NH3
4) Heat the reaction up
5) Decrease the total pressure
6) Increase the total pressure

More 3rd Law of Thermodynamics Questions:
Entropy
Calculate the standard molar entropy change for the combustion of methane (J/mol K).
CH4 (g) + 2 O2 (g) →\rightarrow CO2 (g) + 2 H2O (g)
Thermodynamics
Which of the following statements disagrees with the laws of thermodynamics?
Thermodynamics
Indicate the FALSE statement about the laws of thermodynamics:
Thermodynamics
The Solubility Constant for AgI(s) at 25oC is 8.3x10-17. What is ΔG(rxn) given that the current concentrations of ions are: [Ag+]=9.1x10-9 & [I-]=9.1x10-9
1)Write the variables we know/trying to solve for
2) Out of the different equations for deltaG, which one should we use?
More Gibbs Free Energy + Spontaneity Questions:
Gibbs Free Energy: Spontaneity
If a reaction is nonspontaneous at 298 K with a negative ΔHo, then the reaction is:
Gibbs Free Energy: Spontaneity
For all of the following reactions both ΔGo and ΔHo are negative. For which reactions is ΔGo more negative than ΔHo? (You do not need thermochemical data to answer this question.)
1. SO2 (g) + SrO (s) → SrSO3 (s)
2. N2F4 (g) → 2 NF2 (g)
Gibbs Free Energy
Given the following reaction that occurs in the body, what is ∆Go?
AMP + H20(l) --> Adenosine + Pi + H+ ∆Go'=-13kJ/mol
∆Go'=∆Go + RTlnQ
Gibbs Free Energy: Spontaneity
Based on the following reactions, answer the following questions:
Reaction 1: CO2(g) + CaO(s) ⇌ CaCO3(s) ∆Go= -130.4 kJ/mol
Reaction 2: C(s) + O2(g) ⇌ CO2(g) ∆Go= -394.4 kJ/mol
For a reaction with a negative ΔGo value, which of the following statements is/are FALSE?
1. The equilibrium constant K is greater than one.
2. The reaction is spontaneous when all the reactants and products are in their standard states.
Gibbs Free energy: Spontaneity
For the reaction, A + B → C, ΔHo = +30 kJ; ΔSo=+50 J/K. Therefore the reaction is:
Gibbs Free Energy: Spontaneity
Which spontaneous process occurs because the enthalpy term dominates over the entropic term in the Gibbs free energy equation?
Gibbs Free Energy: Spontaneity
For all of the following reactions both ΔGo and ΔHo are negative. For which reactions is ΔGo more negative than ΔHo? (You do not need thermochemical data to answer this question.)
1. SO2 (g) + SrO (s) → SrSO3 (s)
2. N2F4 (g) → 2 NF2 (g)
A spontaneous process:
Gibbs Free Energy: Spontaneity
If a reaction is nonspontaneous at 298 K with a negative ΔHo, then the reaction is:
Gibbs Free Energy
Determine the value of ΔGo for these reactions.
A process cannot be spontaneous (product-favored) if __________________.
Gibbs Free Energy: Spontaneity
The oxidation of NO is shown below. Using the provided thermodynamic data answer the following questions
2NO(g)+O2(g)⇌2NO2(g)2NO(g)+O_2 (g)⇌2NO_2 (g)
∆H0=−57.1kJ/mol and ∆S0=−73J/K mol at 298K∆H^0=-57.1 kJ/mol \ and \ ∆S^0=-73 J/K\ mol\ at \ 298K
Gibbs Free Energy: Formation
The value of ΔGo for the following reaction is -2745 kJ. Use this value and the information on the Data Sheet to calculate the standard free energy of formation, ΔGfo of C4H10 (g) in kJ/mol.
C4H10 (g) + 13/2 O2 (g) →\rightarrow 4 CO2 (g) + 5 H2O (l)
ΔGfo (CO2(g)) = -394.4 kJ/mol ΔGfo (H2O(l)) = -237.13 kJ/mol
Gibbs Free Energy: Reaction quotient
The standard free energy change (ΔGo) for the reaction of ammonia with water is 29.05 kJ/mol at 25oC.
NH3 (aq) + H2O (l) ⇌ NH4+ (aq) + OH- (aq)
What is the value of ΔG (in kJ/mol) when the concentrations of NH3 (aq) = 0.10 M, NH4+ (aq) = 1.0x10-3 M, and OH- (aq) = 1.0x10-3 M?