CHEM 109
Introduction to Chemistry
Fall 2015
Name:
Examination 3
Multiple Choice Questions
Subatomic Particle Data and a Periodic Table of the Elements can be found at the End of
the Exam.
1.
Elemental Copper and Sulfur, when combined in a crucible and heated, form Cupric
Sulfide:
Copper + Sulfur
Cupric Sulfide
When 3.50g of Copper and 1.77g of Sulfur are combined and heated to a Red Heat, 5.27g
of Cupric Sulfide is formed. Both reagents are completely consumed in this reaction.
What is the ,mass percentage of Sulfur in Cupric Sulfide?
a)
b)
c)
d)
2.
Common grain alcohol has an elemental composition of 52% Carbon, 13% Hydrogen and
35% Oxygen. How many grams of Carbon are contained in 75g of alcohol?
a)
b)
c)
d)
3.
21.6%
29.1%
33.6%
42.8%
17g
39g
51g
67g
Tin (IV) Oxide is 78.8% Tin and 21.2% Oxygen. How many grams of Tin is required to
react with 8.00g of Oxygen?
a)
b)
c)
d)
29.7g
24.3g
21.0g
17.9g
4.
In order to use Law of Combining Volume data to determine the chemical formula of
Water, Avogadro proposed elemental Oxygen would have a chemical formula of:
a)
b)
c)
d)
5.
What did Millikan directly measure in his Oil Drop experiment? What did he infer from
this measurement?
a)
b)
c)
d)
6.
89
65
47
39
An atom of 238U contains how many neutrons?
a)
b)
c)
d)
9.
electron
proton
neutron
quark
An atom of 89Y contains how many protons?
a)
b)
c)
d)
8.
oil drop expansion; mass of the electron
-particle rebound; charge of the electron
oil drop charge; charge of the electron
Cathode Ray deflection; mass/charge for the electron
Which subatomic particle has no charge?
a)
b)
c)
d)
7.
O
O2
O3
O4
84
107
123
146
An atom of O2- contains how many electrons?
a)
b)
c)
d)
8
9
10
11
10.
The charge of a Ca2+ atom is:
a)
b)
c)
d)
11.
+ 3.2 x 10-19 C
+ 1.6 x 10-19 C
- 1.6 x 10-19 C
- 3.2 x 10-19 C
Which subatomic particle is not located in an atom’s nucleus?
a) protons
b) neutrons
c) electrons
12.
An atom’s nucleus is:
a)
b)
c)
d)
13.
Which of the postulates of Dalton's Atomic Theory is currently considered to be true? (May
have multiple correct answers.)
a)
b)
c)
d)
e)
14.
large.
dense.
uncharged.
light.
Elements are composed of indivisible atoms.
Atoms are alike for a given element.
Atoms for different elements differ is size, mass, etc.
Compounds are formed from two or more atoms of different elements.
Atoms combine in simple numerical ratios to form compounds.
Bertholet used the following evidence to argue against Proust's Law of Definite
Composition.
a)
b)
c)
d)
Brass has a variable composition of Copper and Zinc.
Water is a compound.
The composition of Copper Carbonate does not depend on its method of preparation.
Air is composed of variable amounts of Oxygen and Nitrogen.
15.
In the laboratory, we synthesized Copper from Cupric Sulfate. What color is Cupric
Sulfate when dissolved in Water?
a) Red
b) White
c) Blue
Short Answer Questions
1.
Antoine Lavoisier helped over-throw the Doctrine of Phlogiston by heating elemental
Mercury in Air to form a compound referred to as the Red Calx of Mercury. When
strongly heated in a closed retort, the Red Calx decomposes back into elemental Mercury
and Oxygen gas. This sequence was considered impossible by the Doctrine of Phlogiston.
After strong heating of 2.500g of the Red Calx for several days, 2.315g of elemental
Mercury remains.
Red Calx of Mercury
Mercury + Oxygen
(In the following, you must show your work.)
a) How much Oxygen is liberated during this reaction?
b) What is the elemental composition (mass percentage) of the Red Calx of Mercury?
2.
When Element X combines with Oxygen, it forms the oxide XO2, in which 1.00g of X
combines with 1.14g of O. What is the atomic weight of X? Take the atomic weight of
oxygen to be 16 amuo. (You must show your work.)
3.
One of the postulates of Dalton’s Atomic Theory states:
The atoms of a given element are all alike.
In what sense is this true? And, how is this false?
4.
The chemical formula for the compound Aluminum Sulfate is:
Al2(SO4)3
has how many atoms of each constituent element in a "formula unit" of the compound?
Aluminum
Sulfur
Oxygen
5.
Nitrogen reacts with Oxygen to form several different compounds. Two of these are Nitrous
Oxide and Nitric Oxide. If 1.00g of Oxygen is consumed, 1.75g Nitrogen is needed to form
Nitrous Oxide and 0.875g Nitrogen is needed to form Nitric Oxide. Form the following ratio:
=
Suggest chemical formulas for each of these compounds that are consistent with the Law of
Multiple Proportions results.
6.
Provide a basic description of Thomson's Cathode Ray experiment. Your discussion
should address the following:
i) What was measured?
ii) How were the measurements interpreted?
iii) How was the direction of the Cathode Ray confirmed?
7.
Gay-Lussac found that 1 volume of Nitrogen gas combines with 3 volumes of Hydrogen to
produce 2 volume of Ammonia.
a) If Nitrogen and Hydrogen are assumed to be diatomic, N2 and H2, what is the chemical
formula of Ammonia?
b) Illustrate your result schematically below:
Subatomic Particle Data
Charge (C)
Mass (kg)
e- - 1.602 x 10-19
9.1095 x 10-31
p+ + 1.602 x 10-19
1.673 x 10-27
n
1.675 x 10-27
0