CHEM 5013 - Applied Chemical Principles
Suggested problems for Quiz on Thursday September 12
1. For each of the items listed, circle whether what is described is a physical change or a
chemical change.
a. Rusting of Iron
PHYSICAL CHANGE
CHEMICAL CHANGE
b. Evaporation of finger-nail
polish remover from the skin
PHYSICAL CHANGE
CHEMICAL CHANGE
c. Burning of coal
PHYSICAL CHANGE
CHEMICAL CHANGE
d. Fading of a carpet upon
PHYSICAL CHANGE
repeated exposure to the sun
CHEMICAL CHANGE
2. Classify each as a physical property or a chemical property.
a. Tendency of silver to tarnish
PHYSICAL PROPERTY
CHEMICAL PROPERTY
b. Bronze color of copper
PHYSICAL PROPERTY
CHEMICAL PROPERTY
c. Shiny appearance of silver
PHYSICAL PROPERTY
CHEMICAL PROPERTY
d. Flammability of propane gas
PHYSICAL PROPERTY
CHEMICAL PROPERTY
3. Complete the following table: (Note: Type = element, compound, heterogeneous
mixture or homogeneous mixture)
Substance
Example: Oxygen
Pure or Mixture
Pure
Type
Element
Helium gas
PURE
ELEMENT
Concrete
MIXTURE
HETEROGENEOUS
Hot fudge sundae
MIXTURE
HETEROGENEOUS
Ice cubes
PURE
COMPOUND (Water!)
4. What is the difference between an atom’s atomic number and its mass number?
Atomic number = number of protons while Mass number = number of protons plus
number of neutrons
5. Carbon-14 and Nitrogen-14 both have the same mass number, yet they are different
elements. Explain why this is so.
The element’s identity is determined by the atomic number, not the mass number.
Carbon-14 has an atomic number of 6 while Nitrogen-14 has an atomic number of 7.
They, however, both have the same mass number (Carbon-14 has 6 protons and 8
neutrons, while Nitrogen-14 has 7 protons and 7 neutrons).
6. Provide the complete name for each of the following elements:
a. Na
b. Fe
Sodium
Iron
c. S
d. Cu
Sulfur
Copper
7. Provide the atomic symbol for each of the following elements:
a. Helium
b. Nitrogen
He
N
c. Chlorine
d. Phosphorus
Cl
P
e. Mercury
f. Gold
Hg
Au
8. Write the complete atomic symbol (nuclide symbol) for each of the following isotopes:
a. Carbon -13
c. Sodium – 23
13C
23Na
6
11
9. Complete the following table:
# protons
# neutrons
Aluminum-27
13
14
Mg 2+ ion
# electrons
13
Overall Charge
Neutral (0)
12
12
10
+2
Iron - 56
26
30
22
+4
Zirconium - 91
40
51
40
Neutral (0)
24
12
10. Identify the following elements by providing the FULL NAME of each:
a.
24 X
Magnesium
b.
12
c.
104 X
46
58 X
Nickel
28
Palladium
d.
183 X
Tungsten
74
11. The atomic mass of silver is 107.87 amu. There are only two isotopes of silver, 107Ag with
an isotopic mass of 106.91 amu and 109Ag with an isotopic mass of 108.90 amu.
Calculate the fractional abundance of each of the two isotopes of silver.
107.87 = 106.91(x) + 108.90(y) and x+y=1 or y=1-x
107Ag =
107.87 = 106.91(x) + 108.90(1-x)
0.518 (51.8%)
107.87 = 106.91(x) + 108.90 – 108.90 x
109Ag =
-1.03 = -1.99 x
0.482 (48.2%)
X = -1.03/-1.99 = 0.518 and y = 1-x = 1-.518 = 0.482
And X is the fractional abundance of Ag-107 while y is the frac. abund. Of Ag-109
12. The following table represents the percent abundances of the naturally occurring
isotopes of an element.
Isotopic mass (amu) Percent Abundance
23.985
78.99%
24.986
10.00%
25.982
11.01%
a) Calculate the atomic mass of this element
(23.985 x 0.7899) + (24.986 x .1000) + (25.982 x .1101) = 18.95 + 2.499 + 2.861 =
24.31 amu
b) What is the identity of this element? (provide the full name)
Name:
Magnesium