Concept explainers
- (2 pts each) The following reactions have been allowed to reach equilibrium. Consider the following changes that are introduced to the system and predict the direction of the equilibrium shift (to the left or to the right). If no equilibrium shift is expected, write "no change".
- PCl3(g) + Cl2(g) PCl5(g); some PCl5 is removed
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- 2 SO3(g) 2 SO2(g) + O2(g); pressure is increased
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- COBr2(g) + 18.2 kcal CO(g) + Br2(g); temperature is increased
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- 2 NOBr(g) 2 NO(g) + Br2(g); catalyst is added
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- 2 NO(g) + Cl2(g) 2 NOCl(g); exothermic; temperature is increased
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- BaCO3 (s) BaO(s) + CO2(g); BaO is added
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- PCl3(g) + Cl2(g) PCl5(g) + energy; the reaction is cooled
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- HPO42- (aq) + H2O(l) PO43-(aq) + H3O+(aq); NaOH is added
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- C2H4 (g) + I2 (g) C2H4I2 (g) + heat; a catalyst is added
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- AgBr (s) Ag+ (aq) + Br- (aq); AgBr is added
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- (5 points) Use the Henderson-Hasselbalch equation to perform the following calculations. The Ka of acetic acid is 1.8 ´ 10–5.
- Buffer A: Calculate the mass of solid sodium acetate required to mix with 100.0 mL of 0.5 M acetic acid to prepare a pH 4 buffer.
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- Consider the system 4 NH3(g) + 3 O2(g) ⇌ 2 N2(g) + 6 H20(ℓ) ΔrH° = −1530.4 kJ/mol How will the amount of ammonia at equilibrium be affected by removing O2(g) without changing the total gas volume? adding N2(g) without changing the total gas volume? adding water without changing the total gas volume? expanding the container? increasing the temperature? Which of these changes (i to v) increases the value of K? Which decreases it?arrow_forwardConsider an equilibrium mixture of four chemicals (A, B, C, and D, all gases) reacting in a closed flask according to the equation: A(g)+B(g)C(g)+D(g) a. You add more A to the flask. How does the concentration of each chemical compare to its original concentration after equilibrium is reestablished? Justify your answer. b. You have the original setup at equilibrium, and you add more D to the flask. How does the concentration of each chemical compare to its original concentration after equilibrium is reestablished? Justify your answer.arrow_forwardHydrogen and carbon dioxide react at a high temperature to give water and carbon monoxide. H2(g) + CO2(g) H2O(g) + CO(g) (a) Laboratory measurements at 986 C show that there are 0.11 mol each of CO and H2O vapor and 0.087 mol each of H2 and CO2 at equilibrium in a 50.0-L container. Calculate the equilibrium constant for the reaction at 986 C. (b) Suppose 0.010 mol each of H2 and CO2 are placed in a 200.0-L container. When equilibrium is achieved at 986 C, what amounts of CO(g) and H2O(g), in moles, would be present? [Use the value of Kc from part (a).]arrow_forward
- What is Le Chteliers principle? Consider the reaction 2NOCI(g)2NO(g)+Cl2(g) If this reaction is at equilibrium. what happens when the following changes occur? a. NOCI(g) is added. b. NO(g) is added. c. NOCI(g) is removed. d. Cl2(g) is removed. e. The container volume is decreased. For each of these changes, what happens to the value of K for the reaction as equilibrium is reached again? Give an example of a reaction for which the addition or removal of one of the reactants or products has no effect on the equilibrium position. In general, how will the equilibrium position of a gas-phase reaction be affected if the volume of the reaction vessel changes? Are there reactions that will not have their equilibria shifted by a change in volume? Explain. Why does changing the pressure in a rigid container by adding an inert gas not shift the equilibrium position for a gas-phase reaction?arrow_forwardConsider an equilibrium mixture of four chemicals (A. B. C. and D. all gases) reacting in a closed flask according to the following equation: A+BC+Da. You add more A to the flask. How does the concentration of each chemical compare to its original concentration after equilibrium is re-established? Justify your answer. h. You have the original set-up at equilibrium, and add more D to the flask. How does the concentration of each chemical compare to its original concentration after equilibrium is re-established? Justify your answer.arrow_forwardHeating a metal carbonate leads to decomposition. BaCO3(s) BaO(s) + CO2(g) Predict the effect on the equilibrium of each change listed below. Answer by choosing (i) no change, (ii) shifts left or (iii) shifts right. (a) add BaCO3 (b) add CO2 (c) add BaO (d) raise the temperature (e) increase the volume of the flask containing the reactionarrow_forward
- Kp for the following reaction is 0.16 at 25 C: 2 NOBr(g) 2 NO(g) + Br2(g) The enthalpy change for the reaction at standard conditions is + 16.3 kJ/mol-rxn. Predict the effect of the following changes on the position of the equilibrium; that is, state which way the equilibrium will shift (left, right, or no change) when each of the following changes is made. (a) adding more Br2(g) (b) removing some NOBr(g) (c) decreasing the temperature (d) increasing the container volumearrow_forward. Consider an equilibrium mixture consisting of H2O(g), CO(g). H2(g), and CO2(g) reacting in a closed vessel according to the equation H2O(g)+CO(g)H2(g)+CO2(g)a. You add more H2O to the flask. How does the new equilibrium concentration of each chemical compare to its origin al equilibrium concentration after equilibrium is re-established? Justify your answer. b. You add more H2to the flask. How does the concentration of each chemical compare to its original concentration after equilibrium is re-established? Justify your answer.arrow_forwardWhat is the law of mass action? Is it true that the value of K depends on the amounts of reactants and products mixed together initially? Explain. Is it true that reactions with large equilibrium constant values are very fast? Explain. There is only one value of the equilibrium constant for a particular system at a particular temperature, but there is an infinite number of equilibrium positions. Explain.arrow_forward
- The equilibrium constant (Kc) for this reaction is 5.0 at a given temperature. CO(g)+H2O(g)CO2(g)+H2(g) (a) On analysis, an equilibrium mixture of the substances present at the given temperature was found to contain 0.20 mol of CO, 0.30 mol of water vapor, and 0.90 mol of H2 in a liter. How many moles of CO2 were there in the equilibrium mixture? (b) Maintaining the same temperature, additional H2 was added to the system, and some water vapor was removed by drying. A new equilibrium mixture was thereby established containing 0.40 mol of CO, 0.30 mol of water vapor, and 1.2 mol of H2 in a liter. How many moles of CO2 were in the new equilibrium mixture? Compare this with the quantity in part (a), and discuss whether the second value is reasonable. Explain how it is possible for the water vapor concentration to be the same in the two equilibrium solutions even though some vapor was removed before the second equilibrium was established.arrow_forwardSilver undergoes similar reactions as those shown for gold. Both metals react with cyanide ion in the presence of oxygen to form soluble complexes, and both are reduced by zinc. The reaction of Ag+ with cyanide ion may be viewed as two sequential steps: (1) Ag+(aq)+CN(aq)AgCN(s) (2) AgCN(s)+CN(aq)[Ag(CN)2](aq)Ag+(aq)+2CN(aq)[Ag(CN)2](aq)Kf=1.31021 a. Use the solubility product equilibrium constant (Appendix J) of AgCN(s) to determine the equilibrium constant for Step 1. b. Use the equilibrium constants from Step 1 and the overall reaction to determine the equilibrium constant for Step 2. c. Excess AgCN(s) is combined with 1.0 L of 0.0071 M CN (aq) and allowed to equilibrate. Calculate the equilibrium concentrations of CN and [Ag(CN)2] using the equilibrium constant for Step 2. Assume no change in volume occurs.arrow_forwardIn a given experiment, 5.2 moles of pure NOCl was placed in an otherwise empty 2.0-L container. Equilibrium was established by the following reaction: 2NOCl(g)2NO(g)+Cl2(g)K=1.6105 a. Using numerical values for the concentrations in the Initial row and expressions containing the variable x in both the Change and Equilibrium rows, complete the following table summarizing what happens as this reaction reaches equilibrium. Let x = the concentration of Cl2 that is present at equilibrium. b. Calculate the equilibrium concentrations for all species.arrow_forward
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