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Worksheet: Gibbs Energy under Nonstandard Conditions

Q1:

The standard change in Gibbs free energy, Ξ” 𝐺 ⦡ , for the evaporation of water at 298 K is 8.58 kJ/mol. This energy is measured under a standard vapor pressure of 1.00 bar.

At equilibrium, Ξ” 𝐺 = 0 . What is the value of Ξ” 𝐺 to 3 significant figures if the partial pressure of water at 298 K is 0.0110 bar?

Calculate to 3 significant figures the partial pressure of water at equilibrium when the ambient temperature is 298 K.

  • A 3 . 1 3 Γ— 1 0 βˆ’ 2 bar
  • B 2 . 9 9 Γ— 1 0 βˆ’ 3 bar
  • C 1 . 0 8 Γ— 1 0 βˆ’ 2 bar
  • D 1 . 8 4 Γ— 1 0 βˆ’ 2 bar
  • E 3 . 2 8 Γ— 1 0 βˆ’ 3 bar

Q2:

Antimony pentachloride decomposes at high temperature into antimony trichloride and chlorine:

An equilibrium mixture in a 5.000 L flask at 4 4 8 ∘ C contains 3.85 g antimony pentachloride, 9.14 g antimony trichloride, and 2.84 g chlorine.

By expressing the partial pressure of each gas as a fraction of the standard gas pressure of 1.000 bar, calculate to 3 significant figures the equilibrium constant 𝐾 P for this reaction at 4 4 8 ∘ C .

By expressing the partial pressure of each gas as a fraction of the standard gas pressure of 1.000 bar, calculate to 3 significant figures the standard change in Gibbs free energy, Ξ” 𝐺 ⦡ , for this reaction at 4 4 8 ∘ C .

Q3:

A diatomic molecule dissociates into single atoms at high temperature:

At 975 K and a total equilibrium gas pressure of 1.00 bar, 32.4% of the diatomic molecules dissociate. By expressing the partial pressure of each gas as a fraction of the standard gas pressure of 1.00 bar, calculate to 3 significant figures the standard change in Gibbs free energy, Ξ” 𝐺 ⦡ , for this reaction at 975 K.

Q4:

Consider a process in which 0.2 mol of liquid acetone is mixed with 0.8 mol of liquid chloroform at a temperature of 3 5 ∘ C and a pressure of 1 bar. Under these conditions, measurements show that the activity coefficients of the acetone and chloroform constituents of the mixture have the values 0.544 (for acetone) and 0.957 (for chloroform). Given this information, what would be the Ξ” 𝐺 associated with the mixing process?

Q5:

Under certain conditions, gaseous ammonia can decompose into nitrogen and hydrogen gases: When the initial partial pressure of each gas is equal to the standard value of 1.00 atm and the temperature is fixed at 298 K, the change in Gibbs free energy for the reaction, Ξ” 𝐺 ⦡ , is 33.00 kJ/mol. Calculate, to 3 significant figures, the change in Gibbs free energy, Ξ” 𝐺 , when a mixture containing 0.100 mol of each gas is heated to 8 7 5 ∘ C in a 5.00 L container.

Q6:

During glycolysis, an important biochemical pathway responsible for the generation of energy within a cell, glucose-6-phosphate is converted to fructose-6-phosphate. The standard change in Gibbs free energy, Ξ” 𝐺 ⦡ , for this reaction at 3 7 ∘ C is 1.70 kJ/mol. This energy is measured at standard reactant and product concentrations of 1.00 M.

At equilibrium, Ξ” 𝐺 = 0 . What is the value of Ξ” 𝐺 to 3 significant figures at 298 K if the concentration of glucose-6-phosphate is 120 ΞΌM and the concentration of fructose-6-phosphate is 28.0 ΞΌM?

Calculate to 3 significant figures the concentration of glucose-6-phosphate at equilibrium if the ambient temperature is 3 7 ∘ C and the initial glucose concentration is 1.40 M.