CHEM 1405
Exam # 1 (Chap. 1- 3)
Name:_____________________
Score:
PART I – Multiple choice : (3 points each)
-------1. What is the term for the study of the composition and properties of
matter?
a. geology b. chemistry c. alchemy d. physics
-------2. Express 10,000 as a power of 10.
a. 103
b. 10-5
c. 104
d. 105
-------3. How many significant digits are in 0.0250 cm3?
a. 5
b. 2
c. 3
d. 4
-------4. Which of the following unit equations is not correct?
a. 20 dollars = 1 nickel b. 5 nickels = 1 quarter
c. 5 pennies = 1 nickel
d. 4 quarters = 1 dollar
-------5. Round off the measurement 968.543m to three significant digits.
a. 968 m
b. 9682.543 m
c. 9680 m
d. 9700 m
------6. A 4.500 g sample of silver-containing ore was analyzed and found to
contain 1.268 g of pure silver. What is the percentage by mass of pure
silver in the ore?
a. 28.18%
b. 5.768%
c. 5.768%
d. 28.2%
-------7. Which statement about mass measurement is true?
a. Mass is measured using a balance and is not affected by Earth's
gravity.
b. Mass is the force exerted by gravity on an object and is measured
using a balance.
c. Mass is measured using a graduated cylinder and is not affected
by gravity.
d. Both the mass and the weight of an astronaut are the
same on the Moon and on Earth.
-------8. What is the name for the element F?
a. iron
b. fluorine
c. phosphorus
d. flourine
-------9. Hydrogen peroxide is commonly used as an antiseptic and for
bleaching. It is available commercially as a 3.0% solution by mass of
hydrogen peroxide in water. How many grams of hydrogen peroxide are
in a bottle containing 250.0 grams of solution?
a. 8333 g hydrogen peroxide
b. 7.5 g hydrogen peroxide
c. 8.3 x 103 g hydrogen peroxide
d. 7.50 g hydrogen
-------10. Air is made up of nitrogen, oxygen, carbon dioxide, and other gases.
Air is a(n) what?
a. pure substance
b. mixture
c. element
d. compound
-------11. How many hydrogen atoms are in a molecule of acetic acid, HC2H3O2?
a. 4 hydrogen atoms b. 3 hydrogen atoms
c. 1 hydrogen atom
d. 2 hydrogen atoms
-------12. What mass of gold (specific heat = 0.0305 cal/g°C) releases 1.50
kcal of heat when it's cooled from 500.0°C to 25.0°C?
a. 1.97 x 103 g
b. 10.4 g
c. 0.104 g
d. 104 g
-------13. What is the basic unit of volume in the metric system?
a. quart
b. milliliter
c. liter
d. cm3
-------14. Which law states that energy is neither created nor destroyed?
a. law of definite composition
b. law of conservation of energy
c. law of conservation of mass
d. law of conservation of matter
-------15. The melting point of gold is about 1064°C. What is the equivalent
Fahrenheit temperature?
a. 1915°F
b. 623°F
c. 1883°F
d. 1947°F
-------16. Who is generally considered to be the founder of the scientific
method?
a. Robert Boyle
b. Paracelsus
c. Aristotle
d. Antoine Lavoisier
-------17. What is the term for the initial proposal that explains the data
gathered in an experiment?
a. theory
b. opinion
c. appraisal
d. hypothesis
-------18. Which of the following is a semimetal (metalloid)?
a. zirconium
b. bromine
c. gallium
d. arsenic
-------19. Which of the following unit equations is not correct?
a. 106 ns = 1 s
b. 1000 mm = 1 m
c. 1000 g = 1 kg
d. 1 Mbyte = 106 bytes
-------20. In which physical state is there little or no movement of particles
observed?
a. liquid state
b. solid state
PART II – Show your work : (8 points each)
c. gaseous state
d. plasma
1. Perform the following metric-metric conversions.
a) 125 Gm to Mm
b) 255 mg to cg
c) 3 nm to cm
d) 505 in3 to cm3
2.a. The boiling point of nitrogen is -77.0 ºC. What is it on the Fahrenheit
scale?
b. If the temperature outside is 00 F. Express this temperature in 0 C.
3.a. A 4.500 g sample of silver-containing ore was analyzed and found to
contain 1.28g of pure silver. What is the percentage by mass of pure
silver in the ore?
b. What is the density of an object that has a mass of 14.53 g and
occupies a of volume of 5.63 mL?
4.a Metal tiles are decorative alternatives to ceramic and porcelain tiles. A
rectangular tile of solid copper measures 30.5 cm long and 7.5 cm wide.
If the tile’s volume is 115.0 cm3, what is the thickness of the tile?
b. The density of aluminum is 2.70 g/cm3 . If a piece of aluminum foil has a
mass of 6.39 g, then what is its volume in cm3?
5. a. The speed of light is 3.00 x 108 m/s. What is the speed expressed in
kilometers per hour?
b. The radius of tin atom is 1.41 x 10-8 cm. What is the radius of the
atom in nanometers?
Bonus: Answer only one question (10 points)
6. A kettle containing 0.900 liters of water was heated from 20.0 0C to
100.0 0C. How much electrical energy, in kilojoules, was required to
achieve this?
Part II: Answers
1.b 2.c 3.c 4.a 5.c 6.a 7.a 8.b 9.b 10.b 11.a 12.d 13.c 14.b 15.d 16.a 17.d 18.d 19.a 20.b
1. 1 Mm = 106m, •: 125 Gm = 125 x 109 m
= 125 x 103 Mm
2. 10 mg = 1 cg, •: 255 mg = 25.5 cg
3. 3nm = 3 x 10-9 m. (1m = 102 cm),
3 x 10-9 m = 1 m , •: X cm = 3 x 10-7 cm
X cm
102 cm
4. 505 in3 x (2.54) 3 cm3 = 8275.46732
(1) in3
= 8280 cm3
2.a. 0 C = 5/90 F – 32, -77 0 C = 5/90 F – 32, •: 0 F = -81
b. 0 C = 5/90 F – 32, 0 C = 5/9 x 0 0 – 32, •: 0 C = – 32
3.a.
b.
•:
% mass of pure silver in sample= 1.28 g of pure silver
x 100%
4.500 g sample of silver ore
Density (D) =Mass (M) /Volume (V), •: D=14.53 g/ 5.63 mL
4.a. Volume (V) = Length (L) x Width (W) x Height (H)
115.0 cm3 = 30.5 cm x 7.5 cm x H
b.
Density (D) =Mass (M) /Volume (V), •: 2.70 g/cm3 = 6.39 g/ V cm3
5.a. 1.62 Km = 1 mile.
•: 3.00 x 108 m/s = 3.00 x 108 m/s x 1.62 km/3600s x 1 hr/ 1m
b.
1 nm = 10-9 m.
1.41 x 10-8 cm = 1.41 x 10-8 cm x 1m/100cm
= 1.41 x 10-10 m
•: 1.41 x 10-10 m = X nm
= X 10-9 m
-10
•: 1.41 x 10
m = X nm
-9
10
•: X = 1.41 x 10-1 nm
6. At 4 0C, water has a maximum density of 1 g/ml (1 g = 1mL).
0.900 L = 0.900 g,
Quantity of Heat (Q)= mass (m) x Sp. Heat (c) x Temp. Change (Tf – Ti)
Q = 0.900 g x 1 cal/g 0C x (100 – 20) 0C
Chemistry Calculation Precaution: Units must match so that the appropriate units cancels out.