Chemistry 1A Fall 2014 MWF 12:30
1.
Midterm 1
Test Form A
When 3.0 L of chlorine gas (Cl2) reacts with 1.0 L of nitrogen gas (N2), 2.0 L of gaseous product is
formed. All volumes of gases are measured at the same temperature and pressure. What is the
formula of the product?
A) N3Cl
B) NCl4
C) NCl3
D) NCl
E)
N2Cl3
Ans: C
2.
Which of the following atomic symbols is incorrect?
A) 2010Ne
B) 3216S
C) 2814Si
D) 4018Ca
12
E)
6C
Ans: D
3.
Boron naturally occurs in two isotopic forms. The more common isotope is 11B (atomic mass 11.01
amu), which is 80.00% abundant. The average atomic mass of boron is 10.81. What is the mass of
the other isotope?
A) 10.91 amu.
B) 11.00 amu.
C) 10.01 amu.
D) 11.01 amu.
E)
10.81 amu.
Ans: C
4.
A single atom of an element weighs 7.48 × 10–23 g. Identify the isotope.
A) 80Br
B) 35Cl
C) 103Rh
D) 45Sc
E)
none of these
Ans: D
5.
How many hydrogen atoms are in 2.0 g of C2H 5OH?
A)
B)
C)
D)
E)
2.62 x 1022 atoms
1.57 x 1023 atoms
1.38 x 1023 atoms
0.26 atoms
none of the above
Ans: B
6.
What is the molar mass of sucrose (table sugar) with chemical formula C 12H 22O 11?
A)
B)
C)
D)
E)
342 g/mol
350 g/mol
320 g/mol
372 g/mol
none of these
Ans: A
7.
Consider the following unbalanced equation:
C5H12 + O2 → CO2 + H2O
After balancing, you will find that every 1.0 mol of C5H12, requires ___ mol of O2.
A)
B)
C)
D)
E)
1.0
6.5
8.0
13.0
none of these
Ans: C
8.
Consider the following balanced reaction.
2 C 4H 10(g) + 13 O 2(g) → 8 CO 2(g) + 10 H 2O(g)
If a container were to have 20 molecules of C 4H 10 and 26 molecules of O 2 initially, how
many total molecules (reactants plus products) would be present in the container after
this reaction goes to completion? (Use only whole numbers to solve.)
A)
B)
C)
D)
E)
52
47
46
40
none of these
Ans: A
9.
When 0.2 M potassium hydroxide (KOH) and 0.2 M barium nitrate (Ba(NO3) 2) are mixed, a
precipitate is formed. What is the net ionic equation for the formation of this precipitate?
A) Ba2+(aq) + 2NO3–(aq) → Ba(NO3) 2(s)
B) Ba2+(aq) + 2OH–(aq) → Ba(OH)2(s)
C) K+(aq) + OH–(aq) → KOH(s)
D) K+(aq) + NO3–(aq) → KNO3(s)
E)
none of these
Ans: B
10. A compound is composed of 14.0% C, 2.35% H and 83.5% Cl. What is the empirical
formula of this compound?
A)
B)
C)
D)
E)
Ans: A
CH2Cl2
C2H4Cl4
CH2Cl
CHCl2
none of these
11.
What volume of 12.0 M HCl is required to prepare 16.0 L of 0.250 M hydrochloric acid?
A) 130. mL
B) 333 mL
C) 585 mL
D) 768 mL
E)
none of these
Ans: B
12. When the following chemical reaction is balanced, the coefficients in order are:
Pb(NO 3)2 + Na3PO 4 ! Pb3(PO 4)2 + NaNO 3
A)
B)
C)
D)
E)
3, 2, 1, 6
3, 3, 3, 6
1, 1, 1, 1
2, 3, 3, 2
none of these
Ans: A
13.
Consider the following balanced reaction:
CH4(g) + 4Cl2(g) → CCl4(g) + 4HCl(g)
What mass of CCl4 is formed by the reaction of 4.00 g of methane (CH4) with an excess of chlorine
(Cl2)?
A)
B)
C)
D)
E)
1.42 g
7.10 g
14.2 g
38.4 g
none of these
Ans: D
14.
A 12.0-g sample of HF (20.0 g/mol) is dissolved in water to give 3.1 × 102 mL of solution. The
concentration of the solution is
A) 1.9 M
B) 3.7 M
C) 0.19 M
D) 3.9 M
E)
0.60 M
Ans: A
15.
A 0.2500 g sample of a compound known to contain carbon, hydrogen and oxygen
undergoes complete combustion in excess oxygen to produce 0.366 g of CO 2 and 0.150
g of H 2O. What is the empirical formula of this compound?
A)
B)
C)
D)
E)
CH4
CH3OH
C 2H 2O
CHO
CH2O
Ans: E
16.
A 4.00-g sample of an alkaline earth metal chloride (formula MCl2) is treated with
excess silver nitrate (AgNO 3). All of the chloride is recovered as 7.2 g of silver
chloride (AgCl, 143 g/mol). The unknown metal M is:
A) Be
B) Mg
C) Ca
D) Sr
E) Rb
Ans: D
17.
For the balanced chemical reaction:
2 NH 3(g) + 3 O 2(g) + 2 CH 4(g) → 2 HCN(g) + 6 H 2O(g)
if you start with 1.00 mole of each reactant, how many moles of NH 3 will remain once
the reaction is complete?
A) 0.00
B) 1.00
C) 0.666
D) 0.333
E) 0.500
Ans: D
What is the Na+ concentration in a solution prepared by mixing together 100 mL of
0.100 M NaCl and 200 mL of 0.050 M Na 2SO 4?
A) 0.10 M
B) 1.00 M
C) 0.066 M
D) 0.0010 M
E) 0.033 M
Ans: A
18.
19.
What volume of 0.500 M Na3PO 4 is required to precipitate all the lead(II) ions from
200.0 mL of 0.350 M Pb(NO 3)2?
A) 100 mL
B) 70.0 mL
C) 72.6 mL
D) 50.0 mL
E) 93.3 mL
Ans: E
20.
Sodium chromate (Na2CrO 4) and silver nitrate (AgNO 3) are mixed. Identify the
resulting precipitate.
A) Na2CrO 4
B) NaNO 3
C) AgCrO 4
D) Ag2CrO 4
E) Ag4(CrO 4)2
Ans: D
21.
5.00 g of KOH (56.1 g/mol) is added to 250 mL of H 2O. From this solution, 15 mL is
poured into a 500 mL volumetric flask and water is added to the 500 mL mark. What is
the concentration of this new solution?
A) 0.089 M
B) 0.356 M
C) 0.0053 M
D) 0.0107 M
E) 0.0234 M
Ans: D
22.
What mass of solid Na3PO 4 (163.9 g/mol)is required to make a 3.00 L solution that has
a Na+ concentration of 0.400 M?
A) 21.8 g
B) 42.0 g
C) 3.6 g
D) 197 g
E) 65.6 g
Ans: E