FiltersDone

Question type

Essay

Multiple Choice

Short Answer

True False

Matching

Exam 12: Thermodynamics-Why Chemical Reactions Happen

Show Answer

Share

---

All types

Filters

Study FlashcardsPractice ExamLearn

Question 71

Multiple Choice

Review LaterAdd Note

Review Later

Hydrogen reacts with nitrogen to form ammonia (NH₃) according to the reaction, 3 H₂(g) + N₂(g) $\leftrightarrows$ 2 NH₃(g) .The value of $\Delta$ H ^$\circ$ is -92.38 kJ/mol,and that of $\Delta$ S ^$\circ$ is -198.2 J/mol . K.Estimate $\Delta$ G ^$\circ$ at 350.00 ^$\circ$ C.

A) +1.234 $\times$ 10⁵ kJ/mol
B) +161.8 kJ/mol
C) -215.9 kJ/mol
D) -23.0 kJ/mol
E) +31.1 kJ/mol

Correct Answer

verified

Show Answer

Question 72

Multiple Choice

Review LaterAdd Note

Review Later

Indicate which one of the following reactions results in a negative $\Delta$ S_sys.

A) H₂O(g) $\leftrightarrows$ H₂O(s)
B) CaCO₃(s) $\leftrightarrows$ CaO(s) + CO₂(g)
C) CuSO₄ $\leftrightarrows$ 5 H₂O(s) $\leftrightarrows$ CuSO₄(s) + 5 H₂O(g)
D) 14 O₂(g) + 3 NH₄NO₃(s) + C₁₀H₂₂ $\leftrightarrows$ 3 N₂(g) + 17 H₂O(g) + 10 CO₂(g)
E) CO₂(aq) $\leftrightarrows$ CO₂(g)

Correct Answer

verified

Show Answer

Question 73

Multiple Choice

Review LaterAdd Note

If a reaction A $\to$ B has ,then when the reaction is at equilibrium there will be __________

Estimate the standard molar entropy of 1.00 M aqueous Mg²⁺ using the following information: $\Delta$ S ^$\circ$ for the reaction,Mg(s) + 2 HCl(aq) $\leftrightarrows$ MgCl₂(aq) + H₂(g) ,is -43.02 J/K.

Consider the reaction HgO(s) + Zn(s) $\to$ ZnO(s) + Hg(s) ,for which $\Delta$ H ^$\circ$ = -259.7 kJ/mol and $\Delta$ S ^$\circ$ = 7.8 J/mol . K.Which of the following statements regarding its temperature dependence is true?

Indicate which of the following has the lowest standard molar entropy (S ^$\circ$ ) .

In a biochemical reaction,A + B $\to$ C with = 30 kJ/mol.Which of the following reactions might be effectively coupled to this reaction so that it becomes more spontaneous? (I) C + D $\to$ B + E = -40 kJ/mol (II) C + D $\to$ B + E = +40 kJ/mol

The gas above the liquid in a sealed bottle of soda is primarily carbon dioxide.Carbon dioxide is also dissolved in the soda.When the distribution of carbon dioxide between the gas and liquid is at equilibrium,molecules of carbon dioxide in the gas phase can still dissolve in the liquid phase if they strike the surface and are captured.Similarly,molecules of carbon dioxide can escape from the liquid phase.What is the entropy change of the universe, $\Delta$ S_univ,for the dissolution of carbon dioxide under these conditions?

The standard molar entropy of lead(II) bromide (PbBr₂) is 161 J/mol . K.What is the entropy of 2.45 g of PbBr₂?

What are the signs of $\Delta$ H ^$\circ$ , $\Delta$ S ^$\circ$ ,and $\Delta$ G ^$\circ$ for the conversion of liquid water to ice at 10 ^$\circ$ C and 1 atm? Briefly explain each answer.

At 25 ^$\circ$ C,a benzene molecule (C₆H₆) has approximately 1.143 $\times$ 10¹⁴ accessible microstates.Estimate the molar entropy of C₆H₆ at 25.0 ^$\circ$ C to two significant figures.

The enthalpy and entropy of vaporization of ammonia at its normal boiling point,-33.34 ^$\circ$ C,are approximately 23.35 kJ/mol and 97.4 J/mol . K,respectively.What would the entropy change of the universe be if one mole of ammonia vapor were to condense in a large room maintained at 30.0 ^$\circ$ C?

What is the overall standard free-energy change for the following two reactions? A + B $\to$ 2 C = $\Delta$ G₁ C + D $\to$ E = $\Delta$ G₂

The heat of fusion for water is 333.6 J/g.What is the entropy change for the universe when 1.00 L of water at 0 ^$\circ$ C freezes at +5 ^$\circ$ C? Comment on the sign.

The standard molar enthalpy and entropy of fusion for benzoic acid are 18.02 kJ/mol and 45.56 J/mol . K,respectively.Will one mole of benzoic acid melt spontaneously in a large room maintained at 32.00 ^$\circ$ C? Calculate $\Delta$ S_univ to support your answer.

Which of the following is/are true for a reversible process at equilibrium? I. $\Delta$ S_univ = 0 II. $\Delta$ S_sys = 0 III. $\Delta$ G_sys = 0

Determine $\Delta$ G_rxn for C₄H₁₀( ) + O₂(g) $\leftrightarrows$ 4 CO₂(g) + 5 H₂O(g) given the following.

Considering the tabulated values for the thermodynamic properties of oxygen gas,why is the standard entropy nonzero but the standard enthalpy and free energy of formation zero?

Determine $\Delta$ S ^$\circ$ for the reaction,Zn(s) + 2 HCl(aq) $\leftrightarrows$ ZnCl₂(aq) + H₂(g) ,given

Which of the following processes are reversible in the thermodynamic sense? I.Iron in the open air rusts. II.NaCl is dissolved in water and then recovered by the evaporation of the water. III.The ice in a mixture of ice and water at 0 ^$\circ$ C and 1 atm melts.