Name
Chemistry 111A General Chemistry
Practice Exam 1
Section 1 - Multiple Choice (mark correct answer on Scantron- 2.5 points each)
1.
0.3020 has how many significant figures?
a)
1
b)
2
c)
3
d)
4
e)
5
2.
Which of the following is a chemical property of matter?
a)
color
b)
density
c)
melting point
d)
specific heat
e)
reactivity
3.
Which of the following elements exists as diatomic molecules?
a)
iodine
b)
sulfur
c)
silicon
d)
boron
e)
neon
4.
A chloride ion, Cl – has the same number of electrons as a(n)
a)
sodium atom
b)
chlorine atom
c)
neon atom
d)
argon atom
e)
magnesium atom
5.
When
a)
b)
c)
d)
e)
6.
If we imagine the nucleus of an atom is the size of the period at the end of this
sentence. About how big is the atom itself?
a)
The same size as the period
b)
The size of a letter O
c)
As big as a baseball
d)
The size of this room
e)
As big as the planet Earth
magnesium combines with oxygen, the reaction involves a
transfer of electrons from Mg to O
transfer of electrons from O to Mg
sharing of electrons between Mg and O
conversion of protons into electrons
net loss of electrons
7.
The average mass of a magnesium atom is 24.305 amu. What fraction of a sample
of magnesium atoms actually has a mass of 24.305 amu?
a)
0%
b)
0.305%
c)
30.5%
d)
50%
e)
100%
8.
Which of the following is always true for a balanced chemical equation?
a)
the number of species on each side is the same
b)
the states of matter are the same
c)
the formulas of compounds on each side are the same
d)
the number of atoms on each side is the same
e)
it shows the proportions by mass in which substances combine with each
other
9.
Which of the following substances contains the smallest number of atoms:
a)
3 molecules of Al(OH)3
b)
4 molecules of CH3OH
c)
2 molecules of NH4NO3
d)
5 molecules of S2Cl2
e)
7 molecules of CO2
10.
Glucose has the empirical formula CH2O and a molar mass of 180 g/mol. What is its
molecular formula?
a)
CH2O
b)
C2H4O2
c)
C3H6O3
d)
C6H6O6
e)
C6H12O6
11.
Which of the following statements is (are) TRUE?
a)
Strong electrolytes produce only a few ions in aqueous solution
b)
Molecular compounds remain intact in aqueous solution
c)
Weak acids are fully ionized in aqueous solution
d)
Reasonably concentrated solutions of salts are good conductors of electricity
e)
b) and d)
12.
Which of the
a)
0.2 M
b)
0.2 M
c)
0.3 M
d)
0.3 M
e)
0.4 M
following solutions has the highest concentration of ions?
AlCl3
Fe2(SO4)3
Li2CO3
Cu(NO3)2
KCrO4
13.
Which of the following is FALSE regarding a limiting reactant?
a)
a reactant that is completely used up in a chemical reaction
b)
the amount of this reactant limits the amount of product that can be formed
c)
a reactant that runs out first before any of the other reactants
d)
the amount of this reactant can be used to calculate the mass of products
e)
the reactant that is left over at the end of the reaction
14.
How many of the following are oxidation-reduction reactions?
NaOH (aq) + HCl (aq)  NaCl (aq) + H2O (l)
Cu (s) + 2AgNO3 (aq)  2Ag (s) + Cu(NO3)2 (aq)
Mg(OH)2 (s)  MgO (s) + H2O (l)
N2 (g) + 3H2 (g)  2NH3 (g)
a)
0
b)
1
c)
2
d)
3
e)
4
15.
Addition of Ca(NO3)2 (aq) to which solution produces a precipitate?
a)
NH4C2H3O2 (aq)
b)
Pb(NO3)2 (aq)
c)
Na3PO4 (aq)
d)
K2S (aq)
e)
NaI (aq)
16.
Which of the following is a weak acid?
a)
H2SO4
b)
HNO3
c)
H3PO4
d)
HCl
e)
HBr
Section 2 Short answers (points as indicated)
(3)
1.
Perform the following calculation to the appropriate number of significant figures
2.357(1.5257-1.011) =
(4)
2.
Balance the following equations representing combustion reactions
a)
Sc (s)
+
O2 (g)

Sc2O3 (s)
b)
CH4O (g)
+
O2 (g)

CO2 (g)
+
H2O (g)
(8)
(8)
(6)
3.
4.
5.
Name the following compounds
a)
H2SeO3 (aq)
b)
N 2 O5
c)
NH4C2H3O2
d)
Ag2CrO4
Write the formulae for the following compounds
a)
Zinc chlorate
b)
Sulfurous acid
c)
Sodium hypochlorite pentahydrate
d)
Lead (II) arsenate
Determine the empirical formula for the compound having the following percent
composition by mass: phosphorus 43.6%, oxygen 56.4%.
If the molecular mass is ~280 g/mol what is the molecular formula?
(5)
6.
You are given a 16 carat gold ring of mass 7.25 g. How many gold atoms are in the
ring? (For gold the carat scale is fraction by mass out of 24)
(8)
(8)
7.
8.
Write balanced molecular, complete ionic, and net ionic equations for the reaction
of
a)
Al (s) and FeCl2 (aq)
b)
H2SO4 (aq) and Ba(OH)2 (aq)
How many grams of each species will be present at the end when 0.500 g of
copper is added to 2.500 g of AgNO3
Cu (s) + 2 AgNO3 (aq)  2 Ag (s) + Cu(NO3)2 (aq)
(10)
9.
25 mL of 0.525 M AgNO3 are added to 25.0 mL of 0.300 M HCl solution. Write a
balanced equation for the reaction.
What ions are left in solution at the end, and what are their concentrations?