CHM 134 General Chemistry I
Exam 1, Fall 2008 – Dr. Steel
Name
SOLUTIONS
Section 1: Multiple Choice. Circle the choice that is the best answer to each question. Each question in this
section is worth 2 points.
1) Choose the pure substance from the list below.
A) sea water
B) sugar
C) air
D) lemonade
E) milk
2) Choose the heterogeneous mixture from the list below.
A) gatorade
B) chlorine gas
C) black coffee
D) chicken noodle soup E) carbon (graphite)
3) Choose the homogeneous mixture from the list below.
A)kool-aid
B)mud
C)ice water
D)salad dressing
E) salsa
4) Molecules can be described as
A)
B)
C)
D)
E)
a mixture of two or more pure substances.
a mixture of two or more elements that has a specific ratio between components.
two or more atoms joined together in a specific geometric arrangement.
a heterogeneous mixture
a homogeneous mixture
5) Which of the following statements about the phases of matter is TRUE?
A)
B)
C)
D)
E)
In both solids and liquids, the atoms or molecules pack closely to one another.
Solids are highly compressible.
Gaseous substances have long-range repeating order.
There is only one type of geometric arrangement that the atoms or molecules in any solid can adopt.
Liquids have a large portion of empty volume between molecules.
6) Which of the following are examples of physical change?
A)
B)
C)
D)
E)
sugar is dissolved in water.
coffee is brewed.
dry ice sublimes.
ice (solid water) melts.
All of these are examples of physical change.
7) Which of the following are examples of a chemical change?
A)
B)
C)
D)
E)
coffee brewing
water boiling
leaves turning color in the fall
salt dissolves in water
None of the above are chemical changes.
8) Read the length of the metal bar with the correct
number of significant figures.
A)
B)
C)
D)
E)
20 cm
15 cm
15.1 cm
15.10 cm
15.100 cm
9) How many mg does a 433 kg sample contain?
A)
B)
C)
D)
E)
4.33×10-4 mg
4.33×107 mg
4.33×10-3 mg
4.33×106 mg
4.33×108 mg
10) All of the following are SI base units of measurement, EXCEPT
A) meter
B) gram
C) second
D) kelvin
E) mole
11) Which of the following contains the FEWEST atoms? You shouldn't need to do a calculation here.
A) 4.0 g Li
B) 4.0 g Na
C) 4.0 g Rb
D) 4.0 g K
E) 4.0 g Ca
D) bromine
E) selenium
D) niobium
E) uranium
12) What does "X" represent in the symbol at right?
A) mercury
B) chlorine
C) scandium
13) What does "X" represent in the symbol at right?
A) tin
B) copper
C) palladium
14) What species is represented by the following information?
p+ = 12
A) Si4+
B) Mg
n° = 14
C) Ne
e- = 12
D) Si
E) Mg2+
15) What species is represented by the following information?
p+ = 47
A) Ag+
B) Nd
C) Pd
n° = 60
e- = 46
D) Ag
E) Pd+
Section 2: Complete each question in the space provided. When possible, partial credit may be assigned if you
show your work. Point values are listed after each question.
16) Calculate the atomic mass of gallium if gallium has 2 naturally occurring isotopes with the following masses
and natural abundances. (5 points)
Ga-69
Ga-71
68.9256 amu
70.9247 amu
60.11%
39.89%
0.6011(68.9256 amu) + 0.3989(709247 amu) = weighted average mass
69.723 amu =
17) What is the mass of 8.49×1024 atoms of lithium? (5 points)
8.49 × 10 24 atoms Li ×
1 mol Li
6.941 g Li
×
= 97.9 g Li
23
1 mol Li
6.022 × 10 atoms Li
18) How many atoms of oxygen are contained in 47.6 g of Al2(CO3)3? The molar mass of Al2(CO3)3 is
233.99 g/mol. (5 points)
47.6 g Al 2 (CO 3 )3 ×
1 mol Al 2 (CO 3 )3
233.99 g Al 2 (CO 3 )3
×
9 mol O
6.022 × 10 23 atoms O
×
= 1.10 × 10 24 atoms O
1 mol Al 2 (CO 3 )3
1 mol O
19) How many significant figures are in each of the following measurements? (4 points)
7
1009.630 mL
4
3.408×104 m
6
463.090 K
4
0.0005890 g
20) Write the correct atomic symbol for each of the following elements. (5 points)
Mg
magnesium
As
arsenic
C
carbon
Ni
nickel
K
potassium
Ca
calcium
Fe
iron
Ag
silver
Si
silicon
Kr
krypton
21) Complete each calculation and report your answer with the correct number of significant figures. (6 points)
.
4.57
.
(965.43×3.911) + 9413.4136
13 189
.
1.72
.
.
.
.
22) Provide the lowest, whole-number coefficients needed to properly balance each equation. A blank will be
assumed to be a coefficient of 1. (5 points)
6
HCl(aq)
+
C6H12O6(s) +
Fe2O3(s)
→
3
H2O(l)
+
3
N2H4(l)
→
4
NH3(g)
+
6
O2(g)
→
6
CO2(g)
+
2
FeCl3(s)
N2(g)
6
H2O(l)
23) Determine the empirical formula for a compound that contains C, H and O if it contains 52.14% C and
34.73% O by mass. (5 points)
Assume a 100-g sample of the compound:
1 mol C
= 4.34 ÷ 2.17 = 2
12.01 g C
1 mol H
13.13 % H ⇒ 13.13 g H ×
= 13.03 ÷ 2.17 = 6
1.008 g H
1 mol O
34.73 % O ⇒ 34.73 g O ×
= 2.17 ÷ 2.17 = 1
16.00 g O
The formula is C2H6O.
52.14 % C ⇒ 52.14 g C ×
24) An old bullet (which you suspect is lead) in the shape of a ball is found to have a mass of 10.31 grams. If the
diameter of the bullet is 1.220 cm, and the formula for the volume of a sphere is
, what is the density
of the bullet? (5 points)
0.9508
.
10.31 g
0.9508 cm
10.8
25) If the walls in a room are 955 square feet in area, and a quart of paint covers 4.0 square yards, how many
gallons of paint are needed for the room? (3 ft = 1 yd, 1 gal = 4 qt) (5 points)
955 ft
1 yd
3 ft
1 qt
4.0 yd
1 gal
4 qt
6.6 gal
CHM 134 General Chemistry I
Exam 1, Fall 2008 – Dr. Steel
Name
SOLUTIONS
Part 3: Naming and Formulas
Complete the table of names and formulas. Each blank is worth 1 point.
Formula
Name
S4N2
tetrasulfur dinitride
Na2Cr2O7
sodium dichromate
HCl(aq)
hydrochloric acid
SiCl4
silicon tetrachloride
PbS2
lead (IV) sulfide
H2SO3(aq)
sulfurous acid
GaPO4
gallium phosphate
KClO3
potassium chlorate
H2CO3(aq)
carbonic acid
N2O5
dinitrogen pentoxide
Al(CN)3
aluminum cyanide
Ca(NO3)2
calcium nitrate
SF6
sulfur hexafluoride
CrO
chromium (II) oxide
RbCl
rubidium chloride
P2S7
diphosphorus heptasulfide
Br3F9
tribromine nonafluoride
SiO2
silicon dioxide
NH4Cl
ammonium chloride
HBr(aq)
hydrobromic acid