11/25/13
CHEM 4 Exam 3: Ch. 11, 12, 13, 15
and Exp. 12
Open-End Questions and Problems
Please read the following. To receive full credit for a question or a problem, in addition to the
correct answer, you must show a neat, complete, and logical method of solution where each
number is labeled with the appropriate unit and the final answer is rounded to the correct
number of significant digits. The correct answer without any work shown will generally get
zero credit! When an explanation is required, it should be brief, but accurate and complete.
There are 8 questions for a total of 100 points. (Exam 3 part with multiple choice questions is
worth 50 points. Both parts combined are 100 points total.
1. (14 points) Fill the blanks.
The formula unit of ammonium sulfide as a combination of Lewis formulas for individual
ions (use dashes to indicate covalent bonds only):
G-i ~1~ . 5.. . .];;),l ..
[H-~-HJ~
The formula
for~mmonium sulfide in conventional notation: -l0,.-'M_'h_~-+i+-~...,.._S-=-----
The formula wer~rof
ammonium sulfide: - 68.-/)
amu.
--
One mole of ammonium sulfide contains
The molar mass of
ammonium sulfide: _6_.8_._IS
_ _ glmol.
3 formula units;
6.
OJ() X/OJ
---------
(,
~ou
x
IOJt; ammomum wns;
___o<
__T_ _ _ _ _
- - - - - - - - - sulfide ions.
2. (14 points) Fill the blanks.
N02-
Formula
N03-
n/k k.
nr'lrlfe i 0 VI
Name
5 )( I
-1-
16 V f::.
6" )(' r;) -r I ==-
~-=-fEP
Lewis Structure
(Dots & Dashes Style)
l9.=~i:!-a ~J~[:o-N =a]
r-
••
••
••
• •
I
••
.
:o:
.
__,
.J
\:a -IV=O:
L
..
:2:
r· .
:0-{'.1-o:
..
II··
l..Jc;../v~A-rr :O;
I··~
3 a-lo~..s
()/11
54+(~3 +I=~'!J~ =n Ef
o-=::: AI- o= lI
?
Number of Atoms
I
Number of Protons
d3p-t-
3/ f+
Number of Electrons
JLje-
~e
Number of Valence Electrons
!IS
Number of Bonding Electron
Pairs
Number of Lone Electron Pairs
Formal Charge on Nitrogen
Atom
Electron Cloud Geometry
Name ofthe Geometric
Arrangement of Atoms
Sketch of the Geometric
Arrangement of Atoms and Lone
Pairs around the Central Atom
Predicted Ideal Bond Angle
Deviation from the Ideal Bond
Angle (yes or no?)
/3:J1-1ds. co-e. of. f!...R... Sa /A-t..€.....
Le t1(jfh ( y.e s Or ko ?)
-
J.Y
3
If
8
6
-r I
0
-1-r'frna I ;Ia uru--
-/v;(rua I
bek!f-
[0 ~-- A
N,':::::- 0
1:10°
Yf3
fy,JVn£:_ / / lccwcu-
j.
[
,p/CU«_r
o~AI~o]
0l ~
(c)Qo
/A.-0
-
3. (12 points) Provide a term or a name that matches each of the word descriptions below.
A group of atoms held together by covalent bonds with
the total number of electrons being smaller or larger
than the total number of protons.
ion
'
'
A chemical compound that is built of ions.
!011tC
A material that contains two or more chemical
substances.
mi x-1«.-re..
I
A combination of atoms that corresponds to the formula
of an ionic compound or a non-molecular covalent
compound.
A material that has definite chemical composition.
The average mass of molecules of a particular substance
expressed in amu.
0
The number that indicates the balance of the numbers of
protons and electrons in an atom or a group of atoms.
A chemical formula that indicates the number of atoms
of each element present in a molecule.
A chemical compound that contains atoms carbon and
other elements (except for oxides of carbon and
carbonates).
'
oganrc
A chemical compound that is made of atoms of two
elements.
b/na.ry
I
The amount of energy required to remove an electron
form an atom or a group of atoms.
A chemical formula that shows the order in which atoms
are connected to each other within a molecule.
I
4. ( 10 points) Examine the following list of chemical formulas to answer questions (a), (b), (c),
(d) and (e). Each of your answers should be one or a few formulas taken from the list.
@)
(NH~)zCO ~
NOz
~
C0f;1;ff}Ouwds
a:...ce__
!OYJ/C-
(a) Which of the corresponding substances
contain(s) a polyatomic cation?
S03
HCzH302
circled
@_;)
(@4B~
SF4
--~-
____M_'fh_J_y_B_r
_________
(b) Which of the corresponding substances
contain(s) a polyatomic anion?
,
,
(c) Which of the corresponding substances
/
contain(s) both ionic and covalent bonds? I( HS I
A!a..ol oo? /
(d) Which of the corresponding substances
contain(s) no ionic bonds?
(!<..!~)~ c 0 I !v'O,;)_I
(e) Which of the corresponding substances
contain(s) no covalent bonds?
~ CrJ
o, / Ntft.;/3;--
so.3 I f(U.If.30d- ( SF7'
SnF:
5. ( 12 points) An aqueous solution may contain one or more of the cations listed below and one
or more of the anions listed below.
ANIONS
chloride ion; sulfate ion;
and nitrate ion
CATIONS
ammonium ion; silver ion; lead(II) ion;
barium ion; and manganese(II) ion
8c?~
(a) A small portion of the solution was reacted with a solution of barium nitrate? The
reaction yielded a white precipitate. What conclusion(s) can be drawn based on the
observation described above. Explain.
.1-;: ~)
&~O (cl
11 #I-/ )
.sui/a-le... ion (
frese"'f- : ca;__ c 4 + 5 0'1 ( q/ __..
't/ 1
..su;jJ is
Also I .sin=
.so;-
/s tre SeMI-
I
11+,
Pb""-f, a.,ol &!!+
cc;__nn.ol- be, fY-€ s;eHf- )11 ~ :so/c.rh'or?. ( f"L._g_ cor,respo V?d/ 111. ..set!~+ e_,s ~e... /nso lui:; fe_ , J
/OJ-V5
(b) Another PQY'tion of the original solution (not the samiportion that was used in part a)
was reacted with a solution of sodium hydroxide? The reaction yielded a
precipitate. What conclusion(s) can be drawn based on the observations described
above. Explain.
12r.An
u........-~
~1-
d
00 observG--Irotg
cCVV1
be
;:;r.e sel/lf-
;;o0-1
,
~1- (rz-)
;n ff...e._
J
f& Owtf + C£1-iOU:JJf-
:so/a.f,·an ~.e_ Nfl<f
OM cl Mn
Of ~ IC£61-- fwo 1 Mn&+ w: II Y-€G- cl-- w,il- Nc;__Of/( q) :
MM .;)_-f-(6-f.) +c}OH-(6.[,) ~ Mn ( off)a- (s)
+o y!eld a_ (JYe cff /lr::le. , 7ke.. cone lc.-f..510Y/ ,' M11 ;;;.+I on iJ fr-e. serif,
6. (12 points) An aqueous solution of ammonia is added to an aqueous solution of aluminum
nitrate. Write full-formula, complete ionic, and net ionic equations (FFE, CIE, and NIE).
The reaction will go. In each equation, indicate physical state of each reactant and product:
(s), (!),(g), (aq).
(a) An excess of aqueous solution of ammonia is added to an aqueous solution of
phosphoric acid.
FFE:
CIE:
NIE:
~ (NHy) 3 PO'~ ( ttt)
3 Nr6 (G-f,) _,_
f6 PO't ( ti:f,)
3N~(~)-t
i1.3POLf(rvz) ~3NH/(~) -r- PO~-(CL£)
3 N!{_j (~)
+ ~PO'! (czt)
-----?
3
Mfy-r(££) + PO~-(~)
(b) An aqueous solution of ammonia is added to an aqueous solution of iron(II) sulfate.
FF~Aifl~ {G_f,) -r-J- tt;_ O(t) + Fe sol/(~)~ Fe(olf)<X (..s) + (#H~)J. sol' fat)
CI~Aiff3(G£) +cl~ O(t) +Fed-+(~)+ .,sof(ar)~ Fe(OII)d.(s) +J!Jfi{Pi)~7a~)
NIE:
d_AJifJ(rvz) +c)~ 0 (t) + F-e~+(ar) ~ Fe(OH)~ (s) + J !VH~./- (ti-t)
7. (14 points) 50 mL of an aqueous solution containing 0.020 moles oflead(II) nitrate were
thoroughly mixed in a 250-mL beaker with 50 mL of an aqueous solution containing 0.030
moles of potassium iodide.
(a) Write the full-formula, complete ionic, and net ionic equation (FFE, CIE, and NIE) for
the reaction occurred. In each equation, indicate physical state of each reactant and
product: (s), (!),(g), (aq).
FFE: 0. 0:90 yt{..OI
o, 030 VU-O/
Pb(1JrJ2; )d ( 4) -r JKI{u_f:) ~ f6~ (s) + d. 1(1/03 (a~)
~
CIE:
/
PbJ+( ~) -r c) NtJS (q) ~(U.£) + d2 I- (at)~ P6~ (s) -t;~f(f(a:.z) +~Po;fctt)
NIE: J-f
PI::J (~)
+
d.I-(q;)---+ Pbi:J.(s)
(b) Which ions and in what mole amounts will remain in the solution at the completion of
the reaction? Explain. Show work.
0. 0'10
moles of
(). 030 moles of
I Yl/ --1-ic.liy :
Q, 0()0 w-J/ 16 a-.+
N0'2-
0. 00 5"' moles of
1on
0
lOll
Consr.~~cl:
o.ot5"~1
0300~1 !<- +
Q, 03 0 IM-0/
r-
r-
ion
2
0, 005VVt.OI P6 ~+-
do u..o-1- r.ec:c.f;· fl._e_ir
reMAc;.:n vncha.~d.
J
<?--
ion
f2etM(J:A'n iv; s oluf;oYI;
P6 +
O. OL/OtA-W/ Alc6- L :_; ~cl G-/o,- /OUj 1' -1-LR-y
Q,
moles of
f b,;. +
L. 12.
)~
used
up CO~Ntflelely
8. ( 12 points) Place X in all appropriate boxes to indicate types of chemical bonds and
intermolecular forces responsible for the interactions between atoms, ions and molecules in
each sample of matter. (You may use the space below the table to sketch the structures and
shpes of molecules or ions under consideration.)
!1..
~~
..:..~
~
G~ ~~
·~
~~
~~
·:$
~
#
~~~ f:'q;..,
* 6~~
....,~
*
~
X
(..,
~<$. f:'q;
~~
....,~
$
~l~
~
·~
~<$. ;§'
~~
~
....,~
*
~
~~
~~ ~
~ ~~
~
~~
X
NH 4 Cl(s)
)<
H 2 0(I)
X
NH 4 Cl(aq)
X
HCI(l)
X
HCI(aq)
><
CFil)
X
X
CHFil)
X
X
X
CH 30CHil)
)<
X
X
CH 3CH 2 0H(l)
X
X
X
X
><
X
X
X
><
X
X
X
><
X
X
X
X
Cf-0 cHJ-. Of-f
~0
1-h
C
....J
(q)
in
YJ-1.£ ~u
c;__((
5
w CL .f--e_r
(c.-f) c~.s
,.,u.o (e
cu f e_s
f(-6oV~ds
a..n::..
-------
/
f
w,'ll
Cl-f_s
r.e s e H 1-
J'
6e ;or-es.en-1--,
!ovr- cft/ofe /nWcc/iouj 1 wG-1-e.r J;UU ku.-tl€7 J a.ucl /O~
i:J e ;r-€ sevtl-, Wa .f--er ru<J /e cv 1-e s are -/i..R_ elf ole s ,
( Lj
(Jw-efM
St!hsfCMACL
tuO
k utle 5
1
cu, d
H -bouc{s
w!/1 be
ow(
Cfj C~ OH 1-«-0k cu k_;