NAME:~ ~ ..

PERIOD:

CH 13 HOMEWORK .

a. Read CH 13b. Review your notes.c. Answer the following:

1. Characterize a system at equilibrium with respect to each of the following:

(a) The rates of the forward and reverse reactions.

(b) The overall composition of the reaction mixture. •-Jk. ~ ~ 1:;tK.t ~ ..~~ ~.~~ ~~!t-o

~~~.&m~. .

2. Is the following statement true or false? "Reactions with large equilibrium constants arevery fast." Explain. ..

J~ - ~ cwI ~-J ~ ~~ 1Q?1.£ CWt.~

In one experiment, 1.00 mol H20 (g) and 1.00 mol CO (g) are put into a flask and heated to 350°C. In a secondexperiment, l.00 mol H2 (g) and l.00 mol CO2 (g) are put into another flask with the same volume as the first andheated to 350°C. After equilibrium is reached, will there be any difference in the composition of the mixtures in thetwo flasks? . . I . .;Jo) 1:k~ 'A- rM~ r:AAl/t0t ~1. Jk. ~~ ~ .La~.£u4 ~ ~~-Jk~ ~~.~h4t0j~~ ~ wd/L ~ C0n~ 1~J4.(kvl ~.

OVER

--_._--_ .... ------

6. Write the equilibrium expression (K) for each of the following gas-phase reactions:

(a) N7 (g) + O2 (g) <-72 NO (g)- ~K:: [NO]

[tJa J [Oa J(b) SiH4 (g) + 2 Cl, (g) <-7 SiCI4 (g) + 2 H2 (g)

[S~cJ~ ] (W~ J__K. .: -lSll~4 JTCJ.,Jd

7. At a given temperature, K = 1.3 X 10'2 for the reaction.:it

N2 (g) + 3 H2 (g) <-7 'S. NH3 (g)

Calculate the values of K for the following reactions at this temperature.

(a) lj, N2 (g) + 3/2 H2 (g) <-7 NH3 (g)

I ~ -~) y~1< i: 1< = (1."3 y. I 0 =

(b) 2 NH3 (g) <-7 N2 (g) + 3 H2 (g)

" Ik :: K =

(c) NH) (g) <-7 Y, N2 (g) + 3/2 H2 (g)

1<' z: (-' )Ya _ (,~) Yd ii..2,),I< - .ot3 .:

(d) 2 N2 (g) + 6 H2 (g) <-74 NH3 (g)

I () bl1\:: 1< :: (.013) ---"-'~--=-~7,t 1.7 110

8. At high temperatures, elemental nitrogen and oxygen react with one another to form nitrogen monoxide:

N2 (g) + O2 (g) <-7 2 NO (g)

Suppose the system is analyzed at a particular temperature and the equilibrium concentrations are found to be[N2] = 0.041 M, [02] = 0.0078 M, and [NO] = 4.7 X 10'4 M. Calculate the value ofK for the reaction.

Lr-lO]J ("f.7X/O-l,);J- -

(.041)( .0018')

---~~- -,-~-- ~,------.------

9. At a particular temperature a 2.00 L flask at equilibrium contains 2.80 x 10-4 mol of Nj, 2.50 x 10-5 mol of O2,

and 2.0.0 x 10-2 mol N20. Calculate the value of K at this temperature for the reaction:

2 N, (g) + O2 (g) •....•2 N20 (g)

11-.\"2.. 0 J z: .:..9!-L dlOO =.0\ M

-4~,?o '1-..10 .'

«.00 [0<; J s:

-.5d. $0"1(/0

OJ. 0 V

::

a(.0 \)

= -sI. ;} S Y. 10 f'1

10. Distinguish between the terms equilibrium constant and reaction quotient. .vkrJ.h=tl JI4AJ( .xlv. ~",'\IZ r~'do, I( ~ .~ 7~u~t- .•t) ~ ~d~01 G.A»t vWJl ~ ~ , Q1-o ~ .Xc ofdtA/mw Mw- ~ ..uti. ~.M~A~~.11. The magnitude oftlie equilibrium constant is related to the tendency of a reaction to occur. Explain.

'-.IN m~~ f( ~ .f.A-IJ.~ tl- .~ Iuw ~~ ~ o-t

~U a1 ." -0, IJ~ k' A-o krfJ'~ ck·~. tJ~ I(~~) ~~. .

12. For the reaction

Hz (g) + Br2 (g) •....•2 HBr (g)

K, = 3.5 X 104 at 1495K. What is the value ofKp for the following reactions at1495K?

(a) HBr (g) •....•Y, H2 (g) + Y,Br2 (g)I ( .s: ) Yi). , __

Kf '" Kp = --{ 3. S X lOll

(b) 2 HBr (g) •....•H2 (g) + Br2 (g)I I I

l<p = I<p = -3-. S-y..-,-O<{

(c) Y,H2 (g) + Y, Br (g) •....•HBr (g)

OVER

13. The following equilibrium pressures at a certain temperature were observed for the reaction:

2 N02 (g) •....•2 NO (g) + O2 (g)

PN02 = 0.55 atm PNO = 6.5 x 10-5 atm PQ2= 4.5 X 10-5 atm

Calculate the value ofthe equilibrium constant K, at this temperature.

1« .: (P~o ) (Pez. )

( PtJ:l. )

~

.. -~----.- LJ:: ~,3 X/O

. -_. ~.-

14. At 25.0oC, K = 3.7 X 109 for the reaction

CO (g) + ci, (g) •....•COCh (g)

Calculate K, at this temperature. .

~f .: I«RT)O~ 0 (3.7'<IOq)[c.OKJI)(.,l.qg)J-'

= L~.S X 10115. At 1100 K, K, = 0.25 for the reaction

2 S02 (g) + O2 (g) •....•2 S03 (g)

Calculate K at this temperature.

I<f .: K (RT) t> 1\

-I. ~ S .: K l(.o~;2 I) ( /I co) J

16. Write the expression for K for the following reactions:

(a) P4 (s) + 5 O2 (g) •....•P40lO (s)

I

(b) Sg (s) + 8 O2 (g) •....•8 S02 (g)S'

[SO~JS'[O~J

17. Write the expression for K, for the following reactions:~--.

(a) 4 K02 (s) + 2 H20 (g) •.....•4 KOH (s) + 3 O2 (g)

I<f .: (Po. ) 3

(Pt-\~())l.(b) CO2 (g) + MgO (s) •.....•MgCO} (s)

I

18. In a study of the reaction

At 1200 K it was observed that when the equilibrium partial pressure of water vapor is 15.0 torr, the total pressure atequilibrium is 36.3 torr. Calculate the value of K, for this reaction at 1200 K. Hint: apply Dalton's law of partialpressure. p I~

D P £) Uz.O': 7W = .olq13~8l(J.ffTIlr s: Hzo" r I-It

3£0.3 = IS.Ot PH1. R-I1.: .;2(.3 :. O~KOJ-"~IS97~O

PI-h= .J I. 3 k

z

·4(. OJ~oJ.~3'Sq)

( .01 q 13<O~<.( ~t) '1::

19. The equilibrium constant, K, is 2.40 x 103 at a certain temperature for the reaction[1J1.] [Ol]

. -2 NO (g) •.....•Nz (g) + O2 (g)J.J..c...{OX 10 .::

ltJO ]J.For which of the following sets of conditions is the system at equilibrium? For those that are not at equilibrium, inwhich direction will the system shift?

(a) A 1.00 L flask contains 0.0240 mol NO, 2.00 mol N2, and 4.00 mol O2,

(.2.0)('-1.0)Q z: (.0;;)1./)2. t.36 X 10"

(b) A 2.00 L flask contains 0.0320 mol NO, 0.0620 mol N2, and 4.00 mol O2.

(.03.J.) (t:J,O) DI

Q z C. Ol~)~ :: J. SO 'f..10 Q < k

(c) A 3.00 L flask contains 0.0600 mol NO, 2.40 mol N2, and 1.70 mol O2.

(.~O)( . .sl)

(,OJ.O),;( "I. I x. I 0

OVER

20. The equilibrium constant, K, for the reaction

H2 (g) + F2 (g) r-+ 2 HF (g)

Has a value of 2.1 x 103 at a particular temperature. When the system is analyzed at equilibrium at this temperature,the concentrations of H, (g) and F2 (g) are both found to be 0.0021 M. What is the concentration ofHF (g) in theequilibrium system under these conditions? f J ~

K =- Cl;!=")~ 3 (.;l.I~I03)(.OOd.I)(.OO~') =LHFs: J. , XI 0

[1-\;).1 [P~) {(J.t ¥. 103) (. OOJ-I).;I. s: [HFJ~

[t·\FJ = [HFJ36/.1)(10 t:(.OOJ.I)(.OO;J.I)

21. A 1.00 L flask is filled with 2.00 mol gaseous S02 and 2.00 mol gaseous N02 and heated. After equilibriumwas reached, it was found that 1.30 mol of gaseous NO was present. Assume that the reaction

S02 (g) + N02 (g) r-+ S03 (g) + NO (g)

occurs under these conditions. Calculate the value of he equilibrium constant, K, for this reaction.

SOC! fa) + fJOz. (j);;;::5? S02.~) + ;.JOey)

I J.Oo rl.OO 0 0

C. -1.30 -1.30 +1..30 +/.30

f .10 ,10 (.30 /.30

[So:?] [#.1oJ ( 1.30) (1•.30) L3·~·7--------- e ----...--- =[SO~J [NOd] (.70)(.70)

22. At a particular temperature, 12.0 mol of S03 is placed into a 3.0 L rigid container, and the S03 dissociates bythe reaction

2 S03 (g) •.....•2 S02 (g) + O2 (g) J ,00 'l>'\u.e SOa ~J 0:1

[SOB] Q.4 = 3.06 "".Qo 3.ooL

I

CI:

At equilibrium, 3.00 mol of S02 is present. Calculate K for this reaction.

J S03 (j) ~;J SO;},;;) +- 0 d- ~)

~,O 0 0-"I +)( t- ~

A/-x 'Y VI" //~

:.; (,DO M

z,(SO;}] rO~)

\:'S03Jo?(1,0)2.(.5)

( 3, 0) ~z:

--- -- - - -. ----------

23. At a particular temperature, K = 3.75 for the reaction

SOl (g) + N02 (g) ~ SO) (g) + NO (g)

I.

cE

If all four gases had initial concentrations of 0.800 M, calculate the equilibrium concentrations of the gases.

SC.:t (~) + ,JO.l.lj) ~ SO~~) + JJO fJ)

.~ .~ .8.~+ '"X

.&'-+X1< ~ [SO.5) [NO]

[SOa] [tJo]; 3.7~ (.8+(()( .8~ '"X)

.::

(. ~-.., ) (. g - X)

• ~+ JC, 8'-"'1. :: I,9 J" l{q (to ? 3

• 8-+'X = I.S4~,q33g- I.Q3ib4QI1073y.

.:?Q3('4QI(,1?J'}C ::- ;7I./Qrq333<t5

[S06J: [flO~J :; . ~ _. Ol§.rnJIIl ~

~ \. Sl/SI'1 I

X ::c. oJ Ss I 3 ~ IllS

24. At a particular temperature, K = 1.00 X 102 for the reaction

. H2(g) + 12 (g) +-t 2 HI (g)

In an experiment, 1.00 mol H2 and 1.00 mol h and 1.00 mol HI are introduced into a 1.00 L container. Calculate theconcentrations of all species when equilibrium is reached. .

H,,1(j) +- 'I l. tj) .-? ,;J. 1-/.1 (j)

1.00

+ ~-y.

I + .;l."'t

~( I+ J~)(I-?(){I-/C )

I I. 00 1.00

C -Y- -~E , -""'f l- ')<.

\~ :::[1-11) J.

~lH,.JLI~J

10H ;;})l

z: -r -Y

100 s:

lH~J:: [I~J:; 1'.06 ~ • 7'S:. li.S~[~:L):: 1.-oO'r ~(.7S) : ) J.501"\-]

10 - IO~ z: I+- ;)'l-

q = /Jy

X=·75

OVER

25. At 2200oC, K, = 0.050 for the reaction

ICE

N2 (g) + O2 (g) H 2 NO (g)110

What is the partial pressure of~ in equilibrium with N2 and O2 that were placed in a flask at initial pressures of0.800 atm and 0.200 atm, respectively? . _ 10 ± ~ bl. -~O-.c..N~}(j)t O;}lj) .;-.:? ,.)/JOfj)X=

,'t'C • .J. 0 0-IC -Y- +J-y.

.8-~ .~-y ~~2-

(d'l-) ~

z:

.)0....

-t' 1(.os) iJ_i-.f(3.q~)«oo8)- .o s

~ (.3. q s)

-~3, Cf ~/O ~:: . O.s 0 :: (. g _ "X)(, .;)-)( ) =

(.0 ;)) (. ~ - ~) C. d. -"):);; 4 -x. 01

tf'X-~: .00% - .oSO?C +.oso "I-l.

.3.QS-xl +- .OSO"f- - .oo P = 0

26. At 35°C, K = 1.60 x 10-5 for the reaction

2 NOCI (g) t-> 2 NO (g) + Cl2 (g)

Calculate the concentrations of all species at equilibrium for each of the following original mixtures:

(a) 2.00 mol pure NOCl in a 2.00 L flask

J ~OCQ 'j) -'7 ohiOCJ)'" cs,Cj).:;;..--

:r 1.0 0 0C - ;J.. 'i- -+ a)( +"¥

I: I-~"t d~ 'X

[NOJ2. [c.o~J :I-K = -s (d'X) ('k): I.~ X/O[t-lOtQ] z " (\-a~) 2..

-,5! . (g X 10 =

x'" 0.0f{"

cl~: 1-.:l")C: /-.032.:: .q(o~

~-----------f[NO] z:

[Ch) z

[",oa] z

O. 03;;) fY\

O. 01 to fY\

. M1.00

._-- -----

(b) 1.00 mol NOCI and 1.00 mol NO in a 1.00 L flask

,2 !Joel <j) ~ <2 A10[J)~ CJ~j)I 1.0 /,0 0e. ~ J..'""f.. +;)"{. + "l-E I-;),Y.

-$K:: I·('X/O

x.= (1+.J~)ll~.L

(t_d'l-)l~ = ~~ [a1-2- =

~oCJJ

~'}L.(",~

j, ~ ~IO-s. ~- (I) '2.

-.$'j..o/,(''fIQ

~ " I - ;} (1.(" 'I. / 0'S).: /Iqqi/, 1 ~ I

-5I. (P 'f..IO

/. o "".\ LoJ. OCl" J z:

[NO]:

I.OM

-$

(c) 2.00 mol NOCI and 1.00 mol Cl, in a 1.00 L flask K':. (, (, 'f. f 0

~ #-.lOa lj) ~ :) AlO ~)"I (J2.:J'I oZ.e 0 /,0

C. -J.:y. +d."f +-JC

6 d-d.-y. d')l. /+' X

[NoJ C1uz.] l

1< s:-.$ C~) (,~~)

[NoCj J 1-

s: " ~'/.10 .:

(J.- d"1-)2-

-sr. v )(/0

-s1,(' '110 ;: xl..

}l .= 0.00'-1

OVER

,----,.-., ".,' ---_ ... '., --'_._--_._--

27. Suppose the reaction system

U02 (s) + 4 HF (g}<c->UF4 (g) + 2 H20 (g)

has already reached equilibrium. Predict the effect that each of the following changes has on the equilibriumposition. Tell whether the equilibrium will shift to the right, will shift to the left, or will not be affected.

(a) Additional UOz (s) is added to the system.

(b) The reaction is performed in a glass reaction vessel; HF (g) attacks and reacts with glass.

(c) Water vapor is removed.

28. An important reaction in the commercial production of hydrogen is

CO (g) + HzO (g) <c->Hz (g) + CO2 (g)

How will this system at equilibrium shift in each of the following five cases?

(a) Gaseous carbon dioxide is removed.

(b) Water vapor is added.

(c) The pressure is increased by adding helium gas.

(d) The temperature is increased (the reaction is endothermic).

(e) The pressure is increased by decreasing the volume of the container.

------------------------

29. In which direction will the position of the equilibrium

2 HI (g) +-> H2 (g) + h (g)

be shifted for each ofthe following changes?

(a) H2 (g) is added.

(b) 12 (g) is removed.

(c) HI (g) is removed.

(d) some AI' (g) is added.

(e) The volume ofthe container is doubled.

(f) The temperature is decreased (the reaction is exothermic).

co (g) + 2 H2 (g) - CH30H (g)

30. The reaction to prepare methanol from hydrogen and carbon monoxide is

is exothermic. If you wanted to use this reaction for the production of methanol commercially, would high or lowtemperatures favor a maximum yield? Explain your answer.

OVER

~ ~----~~~----