5. Consider the following reaction: 2NOCI (g) = 2NO (g) + Cl2 (g) a. Write the reaction quotient and the equilibrium constant expression for this reaction. b. What items go into the numerator in the reaction quotient and equilibrium constant expression? c. What items go into the denominator in the reaction quotient and equilibrium constant expression? d. What determines the exponent for each item in the reaction quotient and equilibrium constant expressions? e. What is the difference between the items used in the reaction quotient and the items used in the equilibrium constant expression? f. For reactions in solution, molar concentrations are usually used in equilibrium constant expressions (designated K or Kc). In gases, partial pressures can also be used (designated Kp). Equilibrium partial

5. Consider the following reaction: 2NOCI (g) = 2NO (g) + Cl2 (g) a. Write the reaction quotient and the equilibrium constant expression for this reaction. b. What items go into the numerator in the reaction quotient and equilibrium constant expression? c. What items go into the denominator in the reaction quotient and equilibrium constant expression? d. What determines the exponent for each item in the reaction quotient and equilibrium constant expressions? e. What is the difference between the items used in the reaction quotient and the items used in the equilibrium constant expression? f. For reactions in solution, molar concentrations are usually used in equilibrium constant expressions (designated K or Kc). In gases, partial pressures can also be used (designated Kp). Equilibrium partial

Chemistry for Engineering Students

4th Edition

ISBN:9781337398909

Author:Lawrence S. Brown, Tom Holme

Publisher:Lawrence S. Brown, Tom Holme

Chapter12: Chemical Equilibrium

Section: Chapter Questions

Problem 12.40PAE: Because carbonic acid undergoes a second ionization, the student in Exercise 12.39 is concerned that...

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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?
At 2300 K the equilibrium constant for the formation of NO(g) is 1.7 103. N2(g) + O2(g) 2 NO(g) (a) Analysis shows that the concentrations of N2 and O2 are both 0.25 M, and that of NO is 0.0042 M under certain conditions. Is the system at equilibrium? (b) If the system is not at equilibrium, in which direction does the reaction proceed? (c) When the system is at equilibrium, what are the equilibrium concentrations?
Consider the same reaction as in Question 11. In one experiment 1.0 mole of H2O(g) and 1.0 mole of CO(g) are put into a flask and heated to 350C. In a second experiment 1.0 mole of H2(g) and 1.0 mole of CO2(g) are put into another flask with the same volume as the first. This mixture is also heated to 350C. After equilibrium is reached, will there be any difference in the composition of the mixtures in the two flasks?
12.42 The following reaction is in equilibrium in lake water: HCO,_(aq) + H+(aq)«=*H,CO,(aq) Predict the change in the reaction quotient, Q, for each disturbance below and use that prediction to explain how the equilibrium is shifted by the stress. NaHCOj is added to the lake. H,CO}is added. NaOH is added.
Many sugars undergo a process called mutarotation, in which the sugar molecules interconvert between two isomeric forms, finally reaching an equilibrium between them. This is true for the simple sugar glucose, C6H12O6, which exists in solution in isomeric forms called alpha-glucose and beta-glucose. If a solution of glucose at a certain temperature is analyzed, and it is found that the concentration of alpha-glucose is twice the concentration of beta-glucose, what is the value of K for the interconversion reaction?
Because carbonic acid undergoes a second ionization, the student in Exercise 12.39 is concerned that the hydrogen ion concentration she calculated is not correct. She looks up the equilibrium constant for the reaction HCO,-(aq) «=* H+(aq) + COf'(aq) Upon finding that the equilibrium constant for this reaction is 4.8 X 10“H, she decides that her answer in Exercise 12.39 is correct. Explain her reasoning. A student is simulating the carbonic acid—hydrogen carbonate equilibrium in a lake: H,CO,(aq) 5=6 H+(aq) + HCO,'(aq) K = 4.4 X 10'7She starts with 0.1000 A1 carbonic acid. W hat are the concentrations of all species at equilibrium?
A common type of reaction we will study is that having a very small K value (K 1). Solving for equilibrium concentrations in an equilibrium problem usually requires many mathematical operations to be perfomed. However, the math involved when solving equilibrium problems for reactions having small K values (K 1) is simplified. What assumption is made when solving the equilibrium concentrations for reactions with small K values? Whenever assumptions are made, they must be checked for validity. In general, the 5% rule is used to check the validity of assuming x (or 2 x, 3x, and so on) is very small compared to some number. When x (or 2 x. 3x. and so on) is less than 5% of the number the assumption was made against, then the assumption is said to be valid. If the 5% rule fails, what do you do to solve for the equilibrium concentrations?
Consider the following reaction at 250C: A(s)+2B(g)C(s)+2D(g) (a) Write an equilibrium constant expression for the reaction. Call the equilibrium constant K1. (b) Write an equilibrium constant expression for the formation of one mole of B(g) and call the equilibrium constant K2. (c) Relate K1 and K2.
Kc = 5.6 1012 at 500 K for the dissociation of iodine molecules to iodine atoms. I2(g) 2 I(g) A mixture has [I2] = 0.020 mol/Land [I] = 2.0 108 mol/L. Is the reaction at equilibrium (at 500 K)? If not, which way must the reaction proceed to reach equilibrium?
The following two diagrams represent the composition of an equilibrium mixture for the reaction A2 + B2 2AB at two different temperatures. Based on the diagrams, is the chemical reaction endothermic or exothermic? Explain your answer using Le Chteliers principle. (A atoms are red and B atoms are green in the diagrams.)
. 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.