chem 1b chap 13 exercise 1

8/7/2019 Chem 1B Chap 13 Exercise 1

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Chem 1B Name:________________________

Chapter 13, Exercise #1

1. A bus left the main station with full capacity. At the first stop, 7 passengers got off and none got on

the bus. At the second stop, 5 passengers got off and 1 new passenger got on the bus. At the third

stop, 4 passengers got off and 2 new passengers got on the bus. At the fourth stop, 3 passengers got

off the bus and 3 new passengers got on. At the fifth stop, 4 passengers got off the bus and 4 new

passengers got on. At the sixth stop, 2 passengers got off the bus and 2 new passengers got on. Atthe seventh stop, 3 passengers got off and 3 new passengers got on the bus. At each of the eighth,

ninth and tenth stops, 2 passengers got off and 2 new passengers got on the bus.

(a) What are the net changes in the number of passengers in the bus after the first, second, and third

stops, respectively?

(b) What are the net changes in the number of passengers after the fourth and subsequent stops?

(c) What state may be used to describe the number of passengers in the bus after the fourth stop?

(d) Is the situation in the bus considered static or dynamic in term of the number of its passengers?

Explain.

2. Consider the following reaction: CO(g) + H2O(g) CO2(g) + H2(g)

(a) In one experiment 1.0 mole of H2O and 1.0 mole of CO are placed in a sealed flask and heatedto 350oC. In the second experiment 1.0 mole of H2 and CO2 are placed in another sealed flask of the

same volume and heated to 350oC. After equilibrium is reached in both cases, is there any

difference in the composition of the mixtures in the two flasks?

(b) If the equilibrium concentrations in the above reaction contain CO labeled with isotope 14C, will

the14

C always be found only in the CO or will some be found in the CO2? Explain.

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Chem 1B Name:________________________


3. In an experiment involving the following reaction: N2O4(g) 2NO2(g),

0.10 mole of N2O4 are placed in a 1.0-liter glass tubing, which is then sealed, and the temperature ismaintained at 25oC. The reaction is followed every hour by checking the concentration of NO2,

which is a light brown gas, and the following data are obtained.

Time (hr): 0 1 2 3 4 5 6

[NO2], mol/L: 0.00 0.032 0.050 0.064 0.070 0.074 0.074

(a) Why doesnt the concentration of NO2 increase after the 5th hour? Did the reaction stopped after

five hour has elapsed? What can you deduce as to what has happened to the reaction process after

the 5th hour?

(b) What is the concentration of N2O4 (dinitrogen tetroxide) in the mixture after the 5th hour?

(c) Write the expression for equilibrium constantKc for the above reaction and calculate its value.

4. (a) An equilibrium mixture of H2, N2, and NH3 gases at 500 K contains the following

concentrations: [H2] = 1.197 M, [N2] = 0.399 M, and [NH3] = 0.203 M. Determine the equilibrium

constantKc andKp for the reaction: N2(g) + 3H2(g)2NH3(g) at 500 K. (R = 0.08206L.atm/mol.K)

(b) If the concentration of N2 is increased by 1.000 mol/L, in which direction will the net reaction

occur to reach a new equilibrium position? How would the concentrations of H2 and NH3 change

(that is, increase or decrease) in the new equilibrium mixture?

(c) What is the difference between equilibrium constant(Kc orKp) and reaction quotient(Qc orQp)?

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Chem 1B Name:________________________


5. Consider the reaction: N2(g) + 3H2(g)2NH3(g)

Suppose a mixture containing 1.000 mole of H2 and 1.000 mole of N2 was placed in a 10.00-L flask,

which was then sealed and heated to 473 K. The above reaction occurred until it reached

equilibrium, in which case the mixture was found to contain 2.4 x 10-2 mole of NH3. Calculate the

equilibrium concentrations (in mol/L) of N2, H2 and NH3 at 473 K. Determine the equilibriumconstantKc for the above reaction at 473 K.

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chem 1b chap 13 exercise 1

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