NAME:~
~
PERIOD:
CHAPTER
13 REVIEW
PROBLEMS
1. Write the equilibrium expression for each of the following reactions and state whether the reaction is
homogeneous or heterogeneous.
a.
3 NO (g)
<-7
N20 (g) + N02 (g)
[t-h..o J (N.OI.. ]
[tJoJ"
b.
Ni(CO)4 (g)
<-4
Ni (s) + 4 CO (g)
itoJ"I
CH4 (g) + 2 H2S (g)
C.
I<
d.
<-7
CS2 (g) + 4 H2 (g)
[WaJ4[C~,J
=
[CI..h,) [~2. SJ 2.
2 Ag (s) + Zn2+ (aq)
<-42
Ag+ (aq) + Zn (s)
L'-\5-tJ2
t 1"", ~-IJ
~--......,
2. When the following reactions come to equilibrium, does the equilibrium mixture contain mostly reactants or
mostly products?
a.
N2 (g) + O2 (g)
<-4
2 NO (g)
K = 1.5 X 10-10
Re\c.:rY-\ ~ T..5
b.
2 S02 (g) + O2 (g)
<-4
2 S03 (g)
K = 2.5 x 109
ftWl)IJ("T's
3. At lOOOK, K,
a.
c.
1.85 for the reaction
Calculate the value of'K, for the reaction: S03 (g)
lfr ~
b.
=
;<r
=
1.'~.5
~ \
o.
<-4
S02 (g) + Yz O2 (g)
SY I J
Calculate the value of K, for the reaction: 2 S02 (g) + O2 (g)
2 S03 (g)
<-7
Calculate the value ofK for the reaction in part (b).
3. 4,;) ~ I<
3,Yd.:;
1-< ~
L (.o3JI)
1
(IOOO)J-
I( (,O/;J/80.21t;2)
as». 8~
s:
~
OVER
--_
..
_--
-~
4. Mercury (1) oxide decomposes into elemental mercury and elemental oxygen:
2 Hg-O (s)
a.
<->
4 Hg (I) + Oz(g)
Write the equilibrium constant expression for this reaction in terms of partial pressures.
j{,a
b.
z:
POd,
Explain why we normally exclude pure solids and liquids from the equilibrium constant expression.
~
JJ\L
OAuJ
~
~(:f)1r~
tmk
~
.l. 0Jl~J
.
.
.
5. Gaseous hydrogen iodide is placed in a closed container at 425°C, where it partially decomposes to hydrogen and
iodide:
2 HI (g) ~ H2 (g) + 12 (g)
At equilibrium it is found that [HI] = 3.53 x 10-3 M, [H2]
value of K at that temperature.
K;:
( II. ,q 'I. I ()- tf
[r 01) [I..
b]
[HIJ~
) ( !1. lq
=
4.79
X
10-4 M and [12] = 4.79
X
10-4 M. Calculate the
'" ft(')
(3.53--,./O-5)1.
6. The equilibrium for 2 NO (g) + CI2 <-> 2 NOCI (g) .is established at SOO.OK. An equilibrium mixture of the gases
has partial pressures of 0.0950 atm for NO, 0.171 atm for Cl, , and 0.280 atm for NOCI. Calculate the K, for this
reaction.
(8oCt ') ~
(.d6-0)Z-
-
( ~O)~(PoLY
=
(.oQSoY(·IlI)
7.
a.
How d~es the rea~tion :uotient differ from the e~uilibrium constant?
J\J. ~
A
b.
1l-l,cn=fAL:l'"to
~
~~
~
d~J
t:d-i;
/..M~J",.-f ~.
.'
~/Iv~'
Jh.~~.k~~jfu~~
If
Q < K, in which direction will a reaction proceed in order to reach equilibrium?
'---"u~~
wW ~
16:Jk
1fl) ~~~~
~~
~~#
c.
What condition must be satisfied so Q
=
K?
.
~~»vaU1.~~~~
~1kr~\'~
-------_._-_
.._-------
----
--
- --.- ..-------
.•.. ..
.. ------
--- -- -----
_
.. ----------
--
.
8. At 100°C the equilibrium constant for the reaction COCh (g) <--> CO (g) + CI2 (g) has a value ofK = 2.19 x 10-10•
Indicate whether each of the following mixtures ofCOCh, Co, and Cl, are at equilibrium. If not, which direction
must the reaction shift in order to achieve equilibrium?
a.
= 2.00 x 10-3 M, [CO] = 3.30
[COCI2]
tV :.
[CO
J eel
t )
::
(
3 . JO~ I 0-
[COdt.)
[COCh]
=
4.50 x
M, [CO]
(I.
.=.
[COCh]
1.10
=
/0
.,
;l '1-1(J
- ,)
-3
'(..10-4)
s:
X
.: 1.0QX10
O.oOloq~3
'1(0-1
10-7 M, [Clz] = 2.25 x 10-6 M
)(.J. ss '1-10-")
:.
'lc.OUL.]
(1./.
Q « \(
c.
(~
= 6.62 x 10-1 M
SHI i='T LEl=,
10-2
[to J [ell.)
q -
10 )
(Q.OO
q ).l<
b.
10-6M, [Clj]
X
S~IFT
1-IO-J-)
So
-I;:'
S. so ",,0
KlbHT
= 0.0100 M, [CO] = [Cl.] = 1.48 x 10-(;M
C!
[eo J[c.Ql.J
"y';:
Leoc.h 1
~
(l.tf8'tlO-"')(I.4B'KfO-')
.:
cJ,ICix/O-'O
.01
~ =)<.
AT
EQUILI 'gtllJfr\
9. At 100°C, K = 0.078 for the reaction
In an equilibrium mixture of the three gases, the concentrations of S02Ch == 0.108 M and S02
the equilibrium concentration of Cl-,
=
0.052M.
I{ .: [c£t- J [sOJ. J
.018'
-\.so~Cl2-)
.: [t..hJ(.os.;l)
(.108')
r,
n)
LCA~
(.018') (.106)
:
(.oS~)
10. At 1200 K, K = 3.92 for the reaction
CO (g) + 3 Hz (g) •....•CH4 (g) + H20 (g)
In an equilibrium mixture of the gases, [CO] = 0.30 M, [H2]
equilibrium concentration of CH4•
K:
[HaD)
[tHY
=
0.10 M and [H20]
= 0.02 M. Calculate the
J
[eo J [H6l~
[C~ J (.03-)
3. q ~ -=
LCI~1i
J .:
(. 30) ( • I 0 ).1
3
(3,q~)(,.ao)(
./0)
~. 0588 fVl
\
OVER
(.001)
--------
--
------- ------------- ----
-----------------
Calculate
11. At 900 K the following reaction has a K, = 0.345
2 802 (g) + O2 (g) ~ 2 S03 (g)
In an equilibrium mixture, the partial pressures of802
the partial pressure of the S03.
Kf::
(PsO!l);1
( P so
PS03 ;::..J(.3tJS)(.I".s).;}(7.sS~
Poz- )
7- (
=
C?so~)
=
o
j )
and O2 are 0.165 atm and 0.755 atrn, respectively. Calculate
.
t-
3 L\ S -
(. I~ S )Z (.1 S 5 )
12. The reaction
is used to increase the ratio of hydrogen in synthesis gas (mixtures of CO and H2). Suppose you start with 1.00 mole
each of carbon monoxide and water vapor in a 50.0 L container. Calculate the equilibrium concentration of each
substance. The equilibrium constant, K, is 0.58.
to
.
I
C
E
() ~
•0 ~
-"I-
-X
,Qd-.-y
[(O~
-
COa
-7
Hz-O ~)
-t-
Cj)
fI:LCjI
+)(
0
+'1
X
X
0
oa-}{
o
Lj) +-
1 [I-b J
(')() ("X.)
[coJ[Hz-OJ
{Si
:::
o
O)'-"/-
7~1 S 773/0b
;
• O~-
•
L to J :: O.
[I~l--O ]
[ to~J
0/1 t(
;: O. 0 If
z:
X
701 s 77310h
M
[I-Id
l/ fVl
O. 008105
M
-
'X
J :: 0
0
'I[
008& S fYl
13. Hydrogen and iodine react according to the followirig equation:
Hz (g) + 12 (g)
<-+
2 HI (g)
Suppose 1.00 mole Hz and 2.00 moles lz are placed in a 1.00 L container. Calculate the concentrations ofthe
substances when the mixture comes to equilibrium at 458°C. K = 49.7.;..--------
;:::2 d fir
/1.) CJlt Ia.~)
r
I. 00
c
0
-x
f;JY.
1_,)<:
E
144.(
x
d. 00
-j(
9)
(J
d
J.-3"1t~l
qq,4 _ , Llq, I ~
t./5.
7~
+ tJq,
Il./q.1
z: _
1~
1-;
Y- +
c{x. z,
qq, t( :::0
(l./~. 7 ).
«s <{
-"I)
[Hi/. J
Y~,l:
{p3.7!J-{t;7VJ.3
14Q.lt
2-
1./ q. 7:: (1- -x- )
- (1.f)(tJS.7}(C{./.O)
a (4 s. 7)
Cd-x)
::
(-/lICi,')~
=
=
d"f
cJ-X-
.tJ
.: 0, Oll&
M
[I<1]::
I.07M
[H-1J ~
l.t71'1
14_ Lexan is a plastic used to make compact discs, eyeglass lenses, and bullet-proof glass. One of the compounds
used to make Lexan is phosgene, COCI2, an extremely poisonous gas. Phosgene decomposes by the reaction:
COCh (g)
<->
CO (g) + Ch (g)
For which K, = 6.8 X 10-9 at 100DC. If pure phosgene at an initial pressure of 1.00 atrn decomposes, calculate the
equilibrium pressures of all species.
COcJ.~(jJ
e-?'
Co Cj)
of
ell. ~)
I
1.0
0
0
C
-x
+x
+ll
E
1-
x
X
( p Co )
PtJ.l. )
(
( Pcoc.1.~)
~
'X-~~
~,t-x'o
_qX
z.
::
P:
t:co
= 6.
POl.. =
Pcoc.J.2..;
-s
~.i)...'iIO
,
---(IuO
)
.::
OVER
a 'f.. I 0- S~
s. a 'f. (0-5~
,. 0 ~
J
I
15. Iodine dissociates to form iodine atoms according to the following reaction:
h (g)
K = 5.6
•....•21 (g)
X 10"12
If the initial concentration of iodine molecules is 0.45 M, determine the equilibrium concentrations of all species.
1..
-'7
~
(rt)
.J
..:{
S'
lG)
<.1
0
• LIS
-
J...
....
,
(.~s) (S,~
+ .•.....
,
,..
. <is -'Y-
.".. .,.
~. ~ ~ 10
;)
'X
[I)~
'"'I
_,~ (;J.y')l.-
[r~J
,\P'I-(O
:; S.~ 110
s:
::
7,c1
s:
-
-13
.=- X
7
X 10-
[r:~J:
--
(100
~4S
L{)(2.
z.
/.(e'l-IO-t..M
-7
/.q'l.IO)
.l{.5
)(IO'~) :;
[IJ =.
~
LlxZ-·
-lil.
-'-I~
z: , 7fo
4
I
a,LIS M
~"I-M~
16. Consider the following equilibrium, for which 6.l-I < 0:
2 S02 (g) + O2 (g) •....•2 S03 (g)
How will each of the following changes affect an equilibrium mixture of the three gases?
a.
O2 (g) is added to the system.
\<\(,\4,.
SHIFT
b.
the reaction mixture is heated.
I.6'F"'T
S\-I1FT
c.
the volume of the reaction vessel is doubled.
SHIFT
Lf:FT
d.
a catalyst is added to the mixture.
e.
the total pressure of the system is increased by adding a noble gas.
rJO CH4"'}0~
f.
S03 (g) is removed from the system.
SH I !=T
1<\ G I-h
17. Dinitrogen trioxide decomposes to NO and N02 in an endothermic process (6.H= 40.5 kl/mol).
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 N203 (g)
SHIFI
RIGHT
b. adding more N02 (g)
SHI FT
Lt?F T
c. increasing the volume of the reaction flask
SHI~T
KI~HT
d. lowering the temperature
SHIFT
lEF,
'!.IO
10