Chem Final

M(s) + 3 Ag⁺(aq)→3 Ag(s) + M³⁺(aq) E= +2.46 V Ag⁺(aq) + e⁻→ Ag(s) E= +0.80 V According to the information above, what is the standard reduction potential for The half-reaction : M³⁺(aq)+ 3 e⁻→M(s) a. - 1.66 V b. - 0.06 V c. 0.06 V d. 1.66 V e. 3.26 V

A. - 1.66 V

The specific heat capacity of water is 4.18 J/°C*g. What is the enthalpy change when 10.00g of water is heated from 12.0°C to 27.0°C? a. 627 J b. 609 J c. 6.27 kJ d. 11.9 kJ

A. 627 J

Concent (M) pH → Acid 1 Acid 2 Acid 3 Acid 4 0.010 3.44 2.00 2.92 2.20 0.050 3.09 1.30 2.58 1.73 0.10 2.94 1.00 2.42 1.55 0.50 2.69 0.30 2.08 1.16 1.00 2.44 0.00 1.92 0.98 The pH of solutions of four acids prepared at various concentrations were measured and recorded in the table above. The four acids are, in no particular order, chlorous, hydrochloric, lactic, and propanoic. For which acid is the value of the acid dissociation constant, Ka, the smallest? a. Acid 1 b. Acid 2 c. Acid 3 d. Acid 4

A. Acid 1

When solid ammonium chloride, NH₄Cl(s), is added to water at 25°C, it dissolves and the temperature of the solution decreases. Which of the following is true for the values of ΔH and ΔS for the dissolving process? ΔH ΔS a. Positive Positive b. Positive Negative c. Negative Positive d. Negative Negative

A. Positive Positive

An electric current of 1.00 amperes is passed through an aqueous solution of Ni(NO₃)₂. How long will it take to plate out exactly 1.00 mol of nickel metal? a. 386,000 sec b. 193,000 sec c. 96,500 sec d. 48,200 sec e. 24,100 sec

B. 193,000 sec

Which of the following reactions is unfavorable at low temperatures but becomes favorable as the temperature increases? a. 2 CO(g) + O₂(g) ➝ 2 CO₂(g) ΔH° = -566 kJ, ΔS° = -173 J/K b. 2 H₂O(g) ➝ 2 H₂(g) + O₂(g) ΔH° = 484 kJ, ΔS°= 90.0 J/K c. 2 N₂O(g) ➝ 2 N₂(g) + O₂(g) ΔH° = -164 kJ, ΔS° = 149 J/K d. PbCl₂(s) ➝ Pb₂+(aq) + 2 Cl⁻(aq) ΔH° = 23.4 kJ, ΔS° = -12.5 J/K

B. 2 H₂O(g) ➝ 2 H₂(g) + O₂(g) ΔH° = 484 kJ, ΔS°= 90.0 J/K

PCl₅(g)⇌ PCl₃(g) + Cl₂(g) PCl₅(g) decomposes into PCl₃(g) and Cl₂(g) according to the equation above. A pure sample of PCl₅(g) is placed in a rigid, evacuated 1.00 L container. The initial pressure of the PCl₅(g) is 1.00 atm. The temperature is held constant until the PCl₅(g) reaches equilibrium with its decomposition products. The figures below show the initial and equilibrium conditions of the system. (Picture of circle things) If the decomposition reaction were to go to completion, the total pressure in the container will be: a. 1.4 atm b. 2.0 atm c. 2.8 atm d. 3.0 atm

B. 2.0 atm

Concent (M) pH → Acid 1 Acid 2 Acid 3 Acid 4 0.010 3.44 2.00 2.92 2.20 0.050 3.09 1.30 2.58 1.73 0.10 2.94 1.00 2.42 1.55 0.50 2.69 0.30 2.08 1.16 1.00 2.44 0.00 1.92 0.98 The pH of solutions of four acids prepared at various concentrations were measured and recorded in the table above. The four acids are, in no particular order, chlorous, hydrochloric, lactic, and propanoic. Which of the four acids listed in the table is hydrochloric acid? a. Acid 1 b. Acid 2 c. Acid 3 d. Acid 4

B. Acid 2

H₂C₂O₄(aq) + H₂O(l) ⇌ H₃O⁺(aq) + HC₂O₄⁻(aq) HC₂O₄⁻(aq) + H₂O(l) ⇌ H₃O⁺(aq) + C₂O₄²⁻(aq) H₂O(l) + H₂O(l) ⇌ H₃O⁺(aq) + OH⁻(aq) All the reactions represented above occur in an aqueous solution of oxalic acid. Which of the following represent a Bronsted-Lowry conjugate acid base pair? a. H₂C₂O₄(aq) and C₂O₄²⁻(aq) b. HC₂O₄⁻(aq) and C₂O₄²⁻(aq) c. HC₂O₄⁻(aq) and H₂O(l) d. H₃O⁺(aq) and OH⁻(aq)

B. HC₂O₄⁻(aq) and C₂O₄²⁻(aq)

H₂(g) + I₂(g) <--> 2 HI(g) At 450°C, 2.0 moles each of H2(g), I2(g), and HI(g) are combined in a 1.0 L rigid container. The value of Kc at 450°C is 50. Which of the following will occur as the system moves toward equilibrium? a. More H₂(g) and I₂(g) will form. b. More HI(g) will form c. The total pressure will decrease. d. No net reaction will occur, because the number of molecules is the same on both sides of the equation.

B. More HI(g) will form

Al⁺³(aq) + 3e⁻→ Al(s) E°=-1.66 Ag⁺(aq) + e⁻→ Ag(s) E°=+0.80 According to the standard reduction potentials given above, what is the standard cell potential for the reaction represented below? 3Ag⁺(aq) + Al(s)→ 3Ag(s) + Al⁺³(aq) a. -1.74 V b. +4.06 V c. +2.46 V d. -0.86 V

C. +2.46 V

4 NH₃(g)+3 O₂(g)→2 N₂(g)+6 H₂O(g) If the standard molar heats of formation of ammonia, NH₃(g), and gaseous water, H₂O(g), are -46 kJ/mol and -242 kJ/mol, respectively, what is the value of ΔH₂₇₈° for the reaction represented above? a.-190 kJ/mol b.-290 kJ/mol c.-1270 kJ/mol d.-1640 kJ/mol

C. -1270 kJ/mol

Concent (M) pH → Acid 1 Acid 2 Acid 3 Acid 4 0.010 3.44 2.00 2.92 2.20 0.050 3.09 1.30 2.58 1.73 0.10 2.94 1.00 2.42 1.55 0.50 2.69 0.30 2.08 1.16 1.00 2.44 0.00 1.92 0.98 The pH of solutions of four acids prepared at various concentrations were measured and recorded in the table above. The four acids are, in no particular order, chlorous, hydrochloric, lactic, and propanoic. Of the following species, which has the greatest concentration in a 1.0 M solution of acid 1 at equilibrium? a. OH⁻ b. H₃O⁺ c. Acid 1 d. The conjugate base of acid 1

C. Acid 1

Which of the following equations represents a reaction for which the standard entropy change is positive (ΔS°>0)? a. 3O₂(g)→2O₃(g) b. 2H₂(g)+O₂(g)→2H₂O(l) c. CaCO₃(s)→CaO(s)+CO₂(g) d. I₂(g)+2K→2KI

C. CaCO₃(s)→CaO(s)+CO₂(g)

A student mixes dilute AgNO³(aq) with excess NaCl(aq) to form AgCl(s), as represented by the net ionic equation above. Which of the diagrams below best represents the ions that are present in significant concentrations in the solution? (Ksp for AgCl is 1.8 x 10⁻¹⁰) A. B. C. D.

C. Excess NaCl

catalyst one with graph a. I only b. II only c. I and II only d. I, II, and III

C. I and II only

CO(g) + 2 H₂(g)⇌CH₃OH(g) ΔH<0 The synthesis of CH₃OH(g) from CO(g) and H₂(g) is represented above. The value of Kc for the reaction at 483 K is 14.5. Which of the following explains the effect on the equilibrium constant, Kc, when the temperature of the reaction system is increased to 650 K? a. Kc will increase because the activation energy of the forward reaction increases more than that of the reverse reaction. b. Kc will increase because there are more reactant molecules than product molecules c. Kc will decrease because the reaction is exothermic d. Kc is constant and will not change

C. Kc will decrease because the reaction is exothermic

Under which of the following conditions can an endothermic reaction be thermodynamically favorable? a. ΔG is positive b. ΔS is negative c. TΔS > ΔH d. TΔS = 0

C. TΔS > ΔH

Which of the following solutions has a pH greater than 7.0? a. 0.10 M KBr b. 0.10 M NH₄Cl c. 0.10 M HC₂H₃O₂ d. 0.10 M NaF

D. 0.10 M NaF

In the upper atmosphere the following sequence of reactions results in the destruction of ozone. Cl + O₃ → ClO + O₂ ClO + O → Cl + O₂ In the above mechanism, which of the following is a catalyst for the destruction of ozone? A. ClO B. O C. O₂ D. Cl

D. Cl

A buffer solution with a pH of 3.14 was created by adding 100 mL of 1.00M HF and 100 mL 1.00M NaF. A 5.0L sample of 1.0 HCl was then added to the buffer solution and allowed to react. Which of the following best represents the species, the acid, or the conjugate base, present in the highest concentration and the change in pH after the HCl was added a. F⁻, pH is greater than 3.14 b. F⁻, pH is less than 3.14 c. HF, pH is greater than 3.14 d. HF, pH is less than 3.14

D. HF, pH is less than 3.14

Factors that affect the rate of a chemical reaction include which of the following? I. Frequency of collisions of reactant particles II. Kinetic energy of collisions of reactant particles III. Orientation of reactant particles during collisions a. I and II only b. I and III only c. II and III only d. I, II, and III

D. I, II, and III

2 BaO₂(s)⇌2 BaO(s) + O₂(g) ΔH°=162 kJ/mol A sealed rigid vessel contains BaO₂(s) in equilibrium with BaO(s) and O₂(g) as the represented by the equation above. Which of the following changes will increase the amount of BaO₂(s) within the vessel? a. removing a small amount of O₂(g) b. removing a small amount of BaO(s) c. adding He gas to the vessel d. lowering the temperature

D. lowering the temperature

Which of the following changes is NOT exothermic? a. freezing water b. combustion of butane c. condensing steam d. melting copper

D. melting copper

½ H₂(g) + ½ I₂(s)→HI(g) ΔH = 26 kJ / molrxn ½ H₂(g) + ½ I₂(g)→HI(g) ΔH = -5.0 kJ / molrxn Based on the information above, what is the enthalpy change for the sublimation of iodine, represented below? I₂(s)→I₂(g) a. 15 kJ/mol b. 21 kJ/mol c. 31 kJ/mol d. 42 kJ/mol e. 62 kJ/mol

E. 62 kJ/mol

PCl₃(g) + Cl₂(g)⇌PCl₅(g) + energy Some PCl₃ and Cl₂ are mixed in a container at 200°C and the system reaches equilibrium according to the equation above. Which of the following causes an increase in the number of moles of PCl₅ present at equilibrium? I) Decrease the volume of the container II) Raising the temperature III) Adding a mole of He Gas at constant a. I Only b. II Only c. I and II only d. I, II, and III

A. I Only

Zn(s) is used to reduce other compounds in chemical reactions. If a chemist needs a substance that is more effective in its reducing ability, which of the following species would be the best choice? a. Na b. H⁺ c. K⁺ d. Cl⁻

A. Na

What is the equilibrium expression for this reaction? P₄(s) + 5 O₂(g)⇌P₄O₁₀(s) a. Kc=[P₄O₁₀]/[P₄][O₂]⁵ b. Kc=[P₄O₁₀]/5[P₄][O₂] c. Kc=[O₂]⁵ d. Kc=1/[O₂]

D. Kc=1/[O₂]

5.60 g of solid carbon is placed in a rigid evacuated 2.5 L container. Carbon dioxide is added to the container to a final pressure of 1.50 atm at 298 K. A) Calculate the number of moles of each reactant in the container originally. B) The container is heated to 1100 K and the following reaction occurs: C(s) + CO₂(g) 2 CO(g) ∆H˚ = 173 kJ i. Calculate the pressure in the container at this temperature before the reaction takes place. ii. When equilibrium is reached the pressure inside the container is 9.60 atm. Determine the equilibrium partial pressures of CO₂(g) and CO(g). iii. Write the equilibrium expression for this reaction, Kp. iv. Calculate the value of Kp for this reaction at 1100 K. C) Predict the effect on the number of moles of carbon monoxide of each of the following changes made to this system at equilibrium. Give reasons for your predictions. i. The volume of the container is increased to 5.0 L. ii. The pressure inside the container is increased by adding helium. iii. The temperature of the system is increased to 1200 K.

A) Pv=nRT (1.50)(2.5)=n(0.08206)(298) 0.153 mol CO₂ 5.60 g C x (1 mol/12.01 g)= 0.466 mol C B) i. P₂=P₁(T₂/T₁) P₂=1.50(1100/298) P₂=5.54 atm ii. CO₂=1.42 atm CO=8.18 atm C) i. Moles of CO will increase because as volume increases, pressure decreases and the system will shift to the side with the most gas molecules which will be the products. ii. Moles of CO doesn't change because He is no in Kp and therefore does not affect moles. iii. Moles of CO will increase because a positive ΔH will be a reactant and therefor the system will shift toward products to balance it out.

Fe₃O₄(s) + 4 H₂(g) <===> 3 Fe(s) + 4 H₂O(g) ΔH > 0 For this reaction at equilibrium, which changes will increase the quantity of Fe(s)? I. increasing temperature II. decreasing temperature III. adding Fe₃O₄(s) a. I only b. I and II only c. II and III only d. I,II, and III

A. I only

A possible mechanism for the overall reaction represented above is the following (1) NO(g) + NO(g) → N₂O₂(g) slow (2) N₂O₂(g) + O₂(g) → 2 NO₂(g) fast Which of the following rate expressions agrees best with this possible mechanism? a. Rate = k [NO]² b. Rate = k [NO] / [O₂] c. Rate = k [N₂O₂] [O₂] d. Rate = k [NO]² [O₂]

A. Rate = k [NO]²

A 10.g cube of copper at a temperature T₁ is placed in an insulated cup containing 10.g of water at a temperature T₂. If T₁>T₂, which of the following is true of the system when it has attained thermal equilibrium? (The specific heat of copper is 0.385 J/(g°C) and the specific heat of water is 4.184 J/(g°C)) A. The temperature of the copper changed more than the temperature of the water. B. The temperature of the water changed more than the temperature of the copper. C. The temperature of the water and the copper changed by the same amount. D. The relative temperature changes of the copper and the water cannot be determined without knowing T₁ and T₂.

A. The temperature of the copper changed more than the temperature of the water.

Half-cell 1: strip of Al(s) in 1.00 M Al(NO3)3(aq) Half-cell 2: strip of Cu(s) in 1.00 M Cu(NO3)2(aq) Half-cell 3: strip of Fe(s) in 1.00 M Fe(NO3)2(aq) Galvanic cell: X Half-cells: 1 and 2 Cell reaction: 2Al(s) + 3Cu²⁺(aq) → 2Al³⁺(aq) + 3 Cu(s) Ecell°( V): 2.00 Galvanic cell: Y Half-cells: 1 and 3 Cell reaction: 2Al(s) + 3Fe²⁺(aq) → 2Al³⁺(aq) + 3Fe(s) Ecell°: 1.22 Galvanic Cell: Z Half-cells: 2 and 3 Cell reaction: Fe(s) + Cu²⁺(aq) → Fe²⁺(aq) + Cu(s) Ecell°: ? What is the standard cell potential of galvanic cell Z? a. 0.26 V b. 0.78 V c. 2.34 V d. 3.22 V

B. 0.78 V

PCl₅(g)⇌ PCl₃(g) + Cl₂(g) PCl₅(g) decomposes into PCl₃(g) and Cl₂(g) according to the equation above. A pure sample of PCl₅(g) is placed in a rigid, evacuated 1.00 L container. The initial pressure of the PCl₅(g) is 1.00 atm. The temperature is held constant until the PCl₅(g) reaches equilibrium with its decomposition products. The figures below show the initial and equilibrium conditions of the system. (Picture of circle things) Which of the following statements about Kp, the equilibrium constant for the reaction, is correct? a. Kp > 1 b. Kp < 1 c. Kp = 1 d. It cannot be determined whether Kp > 1, Kp < 1, or Kp = 1 without additional information

B. Kp < 1

CO(g) + 2 H₂(g)⇌CH₃OH(g) ΔH<0 The synthesis of CH₃OH(g) from CO(g) and H₂(g) is represented above. The value of Kc for the reaction at 483 K is 14.5. A 10 mol sample of CO(g) and a 1.0 mol sample of H₂(g) are pumped into a rigid, previously evacuated 2.0 L reaction vessel at 483 K. Which of the following is true about equilibrium? a. [H₂]=2[CO] b. [H₂]<[CO] c. [CO]=[CH₃OH]<[H₂] d. [CO]=[CH₃OH]=[H₂]

B. [H₂]<[CO]

The initial rate data in the table above were obtained for the reaction represented below. What is the experimental rate law for the reaction? a. rate=k[NO][O₂] b. rate=k[NO][O₂]² c. rate=k[NO]²[O₂] d. rate=k[NO]²[O₂]² e. rate=k[NO]/[O₂]

B. k[NO][O₂]2

In all electrochemical cells, the process that takes place at the anode is ____________ and the process that takes place at the cathode is _____________. a. oxidation, oxidation b. oxidation, reduction c. reduction, oxidation d. reduction, reduction

B. oxidation, reduction

The reaction indicated below is thermodynamically spontaneous at 298 K, but becomes nonspontaneous at higher temperatures. Which of the following is true at 298 K? N₂(g) + 3H₂(g) -> 2NH₃(g) A. ΔG, ΔH, and ΔS are all positive. B. ΔG, ΔH, and ΔS are all negative. C. ΔG and ΔH are negative, but ΔS is positive. D. ΔG and ΔH are positive, but ΔS is negative.

B. ΔG, ΔH, and ΔS are all negative.

PCl₅(g)⇌ PCl₃(g) + Cl₂(g) PCl₅(g) decomposes into PCl₃(g) and Cl₂(g) according to the equation above. A pure sample of PCl₅(g) is placed in a rigid, evacuated 1.00 L container. The initial pressure of the PCl₅(g) is 1.00 atm. The temperature is held constant until the PCl₅(g) reaches equilibrium with its decomposition products. The figures below show the initial and equilibrium conditions of the system. (Picture of circle things) Which of the following is the most likely cause for the increase in pressure observed in the container as the reaction reaches equilibrium? a. A decrease in the strength of intermolecular attractions among molecules in the flask b. An increase in the strength of intermolecular attractions among molecules in the flask c. An increase in the number of molecules, which increases the frequency of collisions with the walls of the container d. An increase in the speed of the molecules that then collide with the walls of the container with greater force

C. An increase in the number of molecules, which increases the frequency of collisions with the walls of the container

X2 + Y2 X2Y2 rate = k [X2] 21. A reaction and its experimentally determined rate law are represented above. A chemist proposes two different possible mechanisms for the reaction, which are given below: Mechanism 1 Mechanism 2 X2 2X (slow) X2 2X (slow) X + Y2 XY2 (fast) X + Y2 XY + Y (fast) X + XY X2Y2 (fast) X + XY X2Y (fast) X2Y + Y X2Y2 (fast) Based on the information above, which of the following is true? (A) Only mechanism 1 is consistent with the rate law and valid. (B) Only mechanism 2 is consistent with the rate law and valid. (C) Both mechanism 1 and mechanism 2 are consistent with the rate law and valid (D) Neither mechanism 1 nor mechanism 2 is consistent with the rate law nor valid.

C. Both mechanism 1 and mechanism 2 are consistent with the rate law and valid

The endothermic process of creating a saturated solution of CuF₂ is completed by dissolving enough of the solid in water until some of the solid is left on the bottom of the beaker. Which of the following changes would decrease the amount of solid on the bottom of the beaker? a. Increase the pH of the solution b. Decreasing the temperature c. Increasing the amount of water in the beaker d. Adding more of the CuF₂ solid to the beaker

C. Increasing the amount of water in the beaker

Half-cell 1: strip of Al(s) in 1.00 M Al(NO3)3(aq) Half-cell 2: strip of Cu(s) in 1.00 M Cu(NO3)2(aq) Half-cell 3: strip of Fe(s) in 1.00 M Fe(NO3)2(aq) Galvanic cell: X Half-cells: 1 and 2 Cell reaction: 2Al(s) + 3Cu²⁺(aq) → 2Al³⁺(aq) + 3 Cu(s) Ecell°( V): 2.00 Galvanic cell: Y Half-cells: 1 and 3 Cell reaction: 2Al(s) + 3Fe²⁺(aq) → 2Al³⁺(aq) + 3Fe(s) Ecell°: 1.22 Galvanic Cell: Z Half-cells: 2 and 3 Cell reaction: Fe(s) + Cu²⁺(aq) → Fe²⁺(aq) + Cu(s) Ecell°: ? In galvanic cells Y and Z, which of the following takes place in half cell 3? a. Reduction occurs in both cell Y and cell Z. b. Oxidation occurs in both cell Y and cell Z. c. Reduction occurs in cell Y, and oxidation occurs in cell Z d. Oxidation occurs in cell Y, and reduction occurs in cell Z.

C. Reduction occurs in cell Y, and oxidation occurs in cell Z

CO(g) + 2H₂(g)→ CH₃OH(g) ΔH<0 The synthesis of CH₃OH(g) from CO(g) and H₂(g) is represented above. Which of the following statements is true? a. The energy absorbed as the bonds in the reactants are broken is greater than the energy released as the bonds in the products are formed. b. The energy released as the bonds in the reactants are broken is greater than the energy absorbed as the bonds in the products are formed. c. The energy absorbed as the bonds in the reactants are broken is less than the energy released as the bonds in the products are formed. d. The energy released as the bonds in the reactants are broken is less than the energy absorbed as the bonds in the products are formed.

C. The energy absorbed as the bonds in the reactants are broken is less than the energy released as the bonds in the products are formed.

Half-cell 1: strip of Al(s) in 1.00 M Al(NO3)3(aq) Half-cell 2: strip of Cu(s) in 1.00 M Cu(NO3)2(aq) Half-cell 3: strip of Fe(s) in 1.00 M Fe(NO3)2(aq) Galvanic cell: X Half-cells: 1 and 2 Cell reaction: 2Al(s) + 3Cu²⁺(aq) → 2Al³⁺(aq) + 3 Cu(s) Ecell°( V): 2.00 Galvanic cell: Y Half-cells: 1 and 3 Cell reaction: 2Al(s) + 3Fe²⁺(aq) → 2Al³⁺(aq) + 3Fe(s) Ecell°: 1.22 Galvanic Cell: Z Half-cells: 2 and 3 Cell reaction: Fe(s) + Cu²⁺(aq) → Fe²⁺(aq) + Cu(s) Ecell°: ? If the half cell containing 1.00 M Fe(NO₃)₂(aq) in galvanic cells Y and Z is replaced with a half cell containing 5.00 M Fe(NO₃)₂(aq), what will be the effect on the cell voltage of the two galvanic cells? a. The voltage will increase in both cells. b. The voltage will decrease in both cells. c. The voltage will increase in cell Y and decrease in cell Z. d. The voltage will decrease in cell Y and increase in cell Z.

C. The voltage will increase in cell Y and decrease in cell Z.

PCl₅(g)⇌ PCl₃(g) + Cl₂(g) PCl₅(g) decomposes into PCl₃(g) and Cl₂(g) according to the equation above. A pure sample of PCl₅(g) is placed in a rigid, evacuated 1.00 L container. The initial pressure of the PCl₅(g) is 1.00 atm. The temperature is held constant until the PCl₅(g) reaches equilibrium with its decomposition products. The figures below show the initial and equilibrium conditions of the system. (Picture of circle things) As the reaction progresses toward equilibrium, the rate of the forward reaction a. increases until it becomes the same as the reverse reaction rate at equilibrium b. stays constant before and after equilibrium is reached c. decreases to become a constant nonzero rate at equilibrium d. decreases to become zero at equilibrium

C. decreases to become a constant nonzero rate at equilibrium

If equal volumes of the four acids at a concentration of 0.50 M are each titrated with a strong base, which will require the greatest volume of base to reach the equivalence point? a. Acid 1 b. Acid 2 c. Acid 3 d. All the acids will require the same volume of base to reach the equivalence point.

D. All the acids will require the same volume of base to reach the equivalence point.

At 25 °C, the equilibrium constant for the reaction represented above has a value of 1.3. At 50 °C, the value of the equilibrium constant is less than 1.3. Based on this information, which of the following must be correct? a. The reaction is thermodynamically favorable only at temperatures above 25 °C. b. At 25 °C, ΔG° for the reaction is positive. c. At 25 °C, ΔS° for the reaction is positive d. At 25 °C, ΔH° for the reaction is negative.

D. At 25 °C, ΔH° for the reaction is negative.

H₃PO₄⇌H⁺ + H₂PO₄⁻ Ka1=7.52 x 10⁻³ H₂PO₄⁻⇌H⁺ + HPO₄⁻² Ka2=6.23 x 10⁻⁸ HPO₄⁻²⇌H⁺ + PO₄⁻³ Ka3=2.2 x 10⁻¹³ A 5.0 gram sample of H₃PO₄ is dissolved in 100 mL of water. Using the information above, which of the following species will be at the lowest concentration in the solution? a. H⁺ b. HPO₄⁻² c. H₂PO₄⁻ d. PO₄⁻³

D. PO₄⁻³

Which of the following is true for any substance undergoing the process represented below at its normal melting point? X(s)→X(l) a. ΔS<0 b. ΔH=0 c. ΔH=TΔG d. ΔH=TΔS

D. ΔH=TΔS

NH₄HS(s)⇌NH₃(g) + H₂S(g) ΔH° = +93 kJ The equilibrium above is established by placing solid NH₄HS in an evacuated container at 25°C. At equilibrium some solid NH₄HS remains in the container. Predict and explain each of the following. a) The effect on the equilibrium partial pressure of NH₃ gas when additional solid NH₄HS is introduced into the container. b) The effect on the equilibrium partial pressure of NH₃ when addition H₂S gas is introduced into the container. c) The effect on the mass of solid NH₄HS present when the volume of the container is decreased.

a) Addition of more of a solid in a reaction has no effect on the equilibrium. The partial pressure of NH₃ does not change. The activity of a solid is zero. b) According to Le Chatelier's Principle, the equilibrium shifts away from increases. Adding additional H₂S shifts the equilibrium to the reactant side. This decreases the amount of NH₃ present decreasing the partial pressure of NH₃ c) Decreasing the volume increases the partial pressure of both NH₃ and H₂S. According to Le Chatelier's Principle, the equilibrium will shift toward the reactant which is NH₄HS. Solid NH₄HS has an activity of one and is not affected by an decrease in volume. Since more NH₄HS is being made, its mass will increase

CO(g) + ½ O₂(g) → CO₂(g) The combustion of carbon monoxide is represented by the equation above. a) Determine the value of the standard enthalpy change, ∆Hrxn, for the combustion of CO(g) at 298 K using the following information. C(s) + ½ O₂(g) → CO(g) ∆H298= −110.5 kJ mol⁻¹ C(s) + O₂(g) → CO₂(g) ∆H298 = −393.5 kJ mol⁻¹ b) Determine the value of the standard entropy change, ∆Srxn, for the combustion of CO(g) at 298 K using the information in the following table. Substance ∆Srxn (J/mol⁻¹ K⁻¹) CO(g) 197.7 CO2(g) 213.7 O2(g) 205.1

a) CO(g) → C(s) + ½ O₂(g) ∆H298= +110.5 kJ mol⁻¹ C(s) + O₂(g) → CO₂(g) ∆H298 = −393.5 kJ mol⁻¹ CO(g) + ½ O₂(g) → CO₂(g) ∆H298= −283.0 kJ mol⁻¹ b) ∆Srxn=(213.7) − (197.7 + ½(205.1)) ∆Srxn=-86.6 J/mol*K c)

For the reaction represented below, the value of the equilibrium constant, Kp, is 3.1 x 10⁻⁴ at 700 K. N₂(g) + 3 H₂(g)⇌2 NH₃ a) Write the expression for the equilibrium constant Assume that the initial partial pressures of the gasses are as follows: P(N₂)=0.411atm, P(H₂)=0.903atm, P(NH₃)=0.224atm b) Predict whether the pressure of NH₃ increases, decreases, or stays the same at 700 K if the initial partial pressures are those given above. Justify your answer.

a) Kp= (PNH₃)²/(PN₂)(PH₂)³ b) (.224)²/(.411)(.903)³=.166 3.1x10⁻⁴ < .166 Q>K The pressure of NH₃ must decrease, because Q is bigger than K and there will be a shift toward reactants.

Consider the reaction represented by the equation 2X +2Z→ X₂Z₂. During a reaction in which a large excess of reactant X was present, the concentration of reactant Z was monitored over time. A plot of the natural logarithm of the concentration of Z versus time is shown in the figure above. The order of the reaction with respect to reactant Z is a. Zero order b. First order c. Second order d. Third order

b. First order

The rate of a certain chemical reaction between substances M and N obeys the rate law below. The reaction is first studied with [M] and [N] each 1 × 10-3M. What is the rate of a new experiment with [M] and [N] each 2×10⁻³Molar? r = k [M] [N]² a. 2 b. 4 c. 8 d.16

c. 8