KEY
Name:_ _ _ _ __
Exam 1 SCl11-3314, 4514
13 Sep 2013
Prof. Urban
Your goal is to convince me you know what you are doing. Therefore, show your work clearly and
completely on all problems. Answers without the work shown are not eligible for partial credit. Report
all answers with the appropriate number of significant figures. There will be no partial credit offered on
the nomenclature questions (numbers 1 and 2).
1. Provide the correct formula for each of the following compounds. (8 points)
Kr\t'\D'f
a. potassium permanganate
Hl.SD,;)
b. sulfurous acid
c. copper(II) carbonate
- -...
~101
1'11. F",
d. dinitrogen tetrafluoride
2. Provide a correct name for each of the following formulas. (8 points)
;ro\,\ elII) n;'t-v'A1-<­
-_._-------­
3. In two sentences or less, explain the difference between precision and accuracy? (3 points)
Yr~tlSitM is ho"" dose 6.. se-f o.fvCc.lvt~ evu. -h ~ oiher. A-'cvY'a.L~
is ~w CLoSL 4... V"'(II.( is -h .. ().. ')~V\.dA.t'J ((/r o..u..e"f-eJ) VAlve.
4. How many protons, neutrons, and electrons are in 19F-? (3 points)
q prc-tar'\S'
to V\-tv+;()~5
to elt!'ctrons
5. Write the symbol for the species that has 26 protons, 30 neutrons, and 23 electrons. (3 points)
~
1-+
Fe
6. Provide the name of an element that is an alkali metal. (3 points)
L I~:"''''' (w- ~ otk-tr e((~
I'A (1ydvt'
h+
i \
A).
7. What is the percent by mass of carbon in carbon dioxide? (3 points)
10 (yWlle
o ~ ll» .00 0I.... I.. H ~
c.::::
l'l..D
'3'"
'''0 1.....If
Co1. =: ct 14.0 \ 0I~ l-t I 2.. old .'00% = 2.7.2.1 '7.
4-c.f.o
10
8. A sodium atom has a mass of22.99 amu. What is this in grams? (4 points)
(P.O?..:t. )( 101..'30 a,.t"'tf.(.::
\
d
2. '2. '1 ~ tl W\ IA)(
l~
}('Dt.~a..vt\1.(.
9. What is the molar mass of octane? (4 points)
::.
G..O'Z."Z.
Cg 14,8'
C!
0 1t"'J<.. Ie ~::
(2.01
~. '8 \ g )( 10-2 '3 ,
0
1'6>, 08 3
II 4.
H: /.tJ1i8a!M,lx If::. 1~.lcftfiJ-
2." {~ ,
,14. '2.2.. "d /(t'I.u/-e
10. What is the mass, in grams, of 4.56 x 1023 glucose (C6HI206) molecules? (4 points)
r.
'2.1: .AAAle~
f I""<>l~
18'6.lfo!L
X
~
X
(L,. ::- l~(O.'!:t.
4.;:)~XIO ,r_
~.~:,!~!::,2. ;M-lilf,..A"
/N {,L
()
11. A midshipman drains 25.00 mL of a liquid from a buret into a beaker. The mass ofthe beaker
and the sample is measured on an analytical balance to be 57.4587g. The mass of the empty
beaker is measured to be 32.4587g. To how many significant figures should the midshipman
report the density of the liquid? (4 points)
\ID{VlV\.l ::. 2.~.U7> ~L
,vt ~~:
S'7. c/~'frl
- .3'2. .'1~fi
= ~ 5": l)l>O~g :- I. OOO~/vt\L
u
.d
~S.Oo"..L \-. 4 )'1<\ ,f;'t de/lt~;~
1
t
~ .
0
12. Matter can be classified according the scheme below that was presented in class. Fill in the four
missing blocks. (4 points) AG'.
b()
1>(.1
Matter I
•
Pure Substances
€
I
•
?
•
Mixtures
•
CWlPOZf1,J So
/.trWt ~h
I
•
?
1-h,",D~ e,.(~
•
?
l-I-ef-ero~14t t!tJv S
13. The element silver (Ag) exists in nature as two isotopes: 107 Ag and 109Ag. 107Ag is the more
abundant of the two with 51.839% natural abundance and an isotopic mass of 106.9051 amu.
I i~~What is the isotopic mass, in amu, of the less abundant 109Ag isotope? (8 points)
1<10:
;g:l(P(;O
107. ftt.t~
::
0. ~t tt31)( 1°'.10
.)"1
elMI.o\.)
ttl'Vlf..L
.f-
5"2. q 'I '17
X -::
4..mC4
{;"2.. I.{ <-I q7 a, '"-"­
().4f'"
-I-
(0.'111")( ~(V\"'~s
&. '181(Q I) X
:.(0. lf8lb) X
1-
liM
0
1,0 •
14. Write a balanced chemical equation for the combustion of pentane (CsHd to form carbon
dioxide and water. (5 points)
C s:- 1-\\ 1-
+- 8 01-
.--,
S""f! D'2-
+
b
\;-\'2- D
15. Determine the empirical formula of a hydrocarbon that is 85.71% carbon and 14.29% hydrogen
by mass. What additional evidence is needed to determine the molecular formula of the
hydrocarbon? (6 points)
a
A-sSUIl'lIY>..8 100 S~W1f/~
g"S-. 7I C x ~r.t e.. -;-. 7./3'1 ('IW>(('
a
12. .0/
d
,
,I
Iq.2.~()H x rtrl-Olc.~:
~.
()() i'o
1t/,11f'Utt
c: ),.1 '37 ~
HA.I~I
I
::. I.~n~c,.
16. How many carbon atoms are in a 10.0 ml sample of ethanol (C2H60)? The density of ethanol is
1.042 g/mL. (6 pOints)
ID.o (rIL (2 Itt-Ox
1.6~1..£C:.l.Jr.J)x I ~q{.t
/Yt6/~ C "Ol-2.X1o?,3 a--h;a5_
-----.>'1 -
­
(7,..J..ifl,.D X 2
I J"'1" I( t!z, 11(, 0
<I~'07()
;wL
YIlt D { (
;( .7;). X 102.'"'> C a+(Jt¥t ')
17. A midshipman prepares aspirin in a Plebe Chemistry experiment using the reaction shown
below.
+
2 C7H603
+
C4H 60 3
salicylic acid
acetic anhydride aspirin
180.2 g/mol
138.1 g/mol
102.09 g/mol 1het;( l-n 'C~
'I1lfl ~
a. The midshipman reacts 1.50 g of salicylic acid with an excess of acetic anhydride and
obtains a yield of 1.50 g of aspirin. What is the midshipman's percent yield? (8 points)
r;
I ,;)0"
(.
o
?
Ii 0
t. 'J x
lfY\b{t
I
X
33'.1 '&
2 f'l\olt ('1 J.l~Ocf
'2. W\b(.(
C,
a.. 'l(ii)~o = ,''. s-'7o
I. S-o
i. 'lCtu~
u-t. 0 s
I
X
go.1.J: CtjHS-0t{
/NJ ~
-
_
-
J
41"
1.
,,\PU
~ It U
b. How many grams of acetic anhydride are needed to exactly consume 1.50 g of salicylic
acid? (6 points)
I t'l',./i (" Hlt,03_ X I c) 2.. 0'1 Cy #, °3 :.
1tyW
I. 9 'l ('7 1411 03 J(.
o
t(
-.:..--- )(
O ~,-rw) it ~7'4u 03
13f.I
~
18. The reaction below is used in self-contained breathing devices to convert exhaled C02 into 02.
50.0 g of potassium superoxide (K02) and 50.0g of carbon dioxide are combined and are reacted
to the fullest extent possible. 4K02
+ 2 C02 2 K2C03 + 3 02 71.1 g/mol
44.0 g/mol