A chemical engineer is studying the following reaction: HCN(aq)+ NH,(aq) CN (aq)+NH,(aq) At the temperature the engineer picks, the equilibrium constant K, for this reaction is 0.83, The engineer charges ("fills") four reaction vessels with hydrogen cyanide and ammonia, and lets the reaction begin. He then measures the composition of the mixture inside each vessel from time to time. His first set of measurements are shown in the table below. Predict the changes in the compositions the engineer should expect next time he measures the compositions. reaction vessel compound concentration expected change in concentration HCN 0.48 M O T increase Ol decrease O (no change) NH, 0.40 M O f increase OI decrease O (no change) CN 0.89 M O t increase OI decrease O (no change) NH, 0 98 M O t increase OI decrease O (no change) HCN 106 M O increase O decrease O (no change) NH, 0 95 M O fimerease OI decrease O (no change) CN 085 M O increase Ou decrease O (no change) NH, 0 98 M Aincrease OI decrease O (no change) HCN 037 M 0 ncruase decrease O (no change) NH, 0 29 M Oerease 0. decrease O (no change) CN 100 M O t inrease derease NH, 1 09 M decreaE e dange) Explanation Check

A chemical engineer is studying the following reaction: HCN(aq)+ NH,(aq) CN (aq)+NH,(aq) At the temperature the engineer picks, the equilibrium constant K, for this reaction is 0.83, The engineer charges ("fills") four reaction vessels with hydrogen cyanide and ammonia, and lets the reaction begin. He then measures the composition of the mixture inside each vessel from time to time. His first set of measurements are shown in the table below. Predict the changes in the compositions the engineer should expect next time he measures the compositions. reaction vessel compound concentration expected change in concentration HCN 0.48 M O T increase Ol decrease O (no change) NH, 0.40 M O f increase OI decrease O (no change) CN 0.89 M O t increase OI decrease O (no change) NH, 0 98 M O t increase OI decrease O (no change) HCN 106 M O increase O decrease O (no change) NH, 0 95 M O fimerease OI decrease O (no change) CN 085 M O increase Ou decrease O (no change) NH, 0 98 M Aincrease OI decrease O (no change) HCN 037 M 0 ncruase decrease O (no change) NH, 0 29 M Oerease 0. decrease O (no change) CN 100 M O t inrease derease NH, 1 09 M decreaE e dange) Explanation Check

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 12.41PAE: Because calcium carbonate is a sink for CO32- in a lake, the student in Exercise 12.39 decides to go...

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Describe a nonchemical system that is in equilibrium, and explain how the principles of equilibrium apply to the system.
Because calcium carbonate is a sink for CO32- in a lake, the student in Exercise 12.39 decides to go a step further and examine the equilibrium between carbonate ion and CaCOj. The reaction is Ca2+(aq) + COj2_(aq) ** CaCO,(s) The equilibrium constant for this reaction is 2.1 X 10*. If the initial calcium ion concentration is 0.02 AI and the carbonate concentration is 0.03 AI, what are the equilibrium concentrations of the ions? A student is simulating the carbonic acid—hydrogen carbonate equilibrium in a lake: H2COj(aq) H+(aq) + HCO}‘(aq) K = 4.4 X 10"7 She starts with 0.1000 AI carbonic acid. What are the concentrations of all species at equilibrium?
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 sample of gaseous nitrosyl bromide (NOBr) was placed in a container tiued with a frictionless, massless piston, where it decomposed at 25C according to the following equation: 2NOBr(g)2NO(g)+Br2(g) The initial density of the system was recorded as 4.495 g/L. After equilibrium was reached, the density was noted to be 4.086 g/L. a. Determine the value of the equilibrium constant K for the reaction. b. If Ar(g) is added to the system at equilibrium at constant temperature, what will happen to the equilibrium position? What happens to the value of K? Explain each answer
For a typical equilibrium problem, the value of K and the initial reaction conditions are given for a specific reaction, and you are asked to calculate the equilibrium concentrations. Many of these calculations involve solving a quadratic or cubic equation. What can you do to avoid solving a quadratic or cubic equation and still come up with reasonable equilibrium concentrations?
. Gaseous phosphorus pentachloride decomposes according to the reaction PCl5(g)PCl3(g)+Cl2(g)The equilibrium system was analyzed at a particular temperature, and the concentrations of the substances present were determined to be [PCl5]=1.1102M,[PCl3]=0.325M. and [Cl2]=3.9103M. Calculate the value of K for the reaction.
The diagram represents an equilibrium mixture for the reaction N2(g) + O2(g) ⇌ 2 NO(g) Estimate the equilibrium constant.
Methanol, a common laboratory solvent, poses a threat of blindness or death if consumed in sufficient amounts. Once in the body, the substance is oxidized to produce formaldehyde (embalming fluid) and eventually formic acid. Both of these substances are also toxic in varying levels. The equilibrium between methanol and formaldehyde can be described as follows: CH3OH(aq)H2CO(aq)+H2(aq) Assuming the value of K for this reaction is 3.7 1010, what are the equilibrium concentrations of each species if you start with a 1.24 M solution of methanol? What will happen to the concentration of methanol as the formaldehyde is further converted to formic acid?
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?