Chemistry Question

Introduction to ChemistryExam III
Fall 2022
Reactions and Solutions
Name ______________________
This is an ‘At Home Exam’ due no later than Tues, Dec 6, 2022 by 11:30 p.m. on
Blackboard. Print out this exam. Neatly show all work including units and labels. Answers
with no work will only receive partial credit. If needed, use scratch paper to work out the
question and then neatly show the work in the space provided. Do not attach additional
pages. Submit this exam as one pdf. Do not submit individual pdf pages. Do not submit all
pages on one page. Submit this exam as one pdf with four consecutive pages.
You can use whatever resources needed, except:
Do not copy answers from other students in the class.
Do not ask for help at the Tutoring Center.
1.
Balance the following equations:
8 pts
a.
Cr
+
b.
Al2O3
+
c.
Fe
+
O2
d.
Au2(CO3)3
+
Cl2
H2O
CrCl3
Al(OH)3
Fe2O3
NaCl
Na2CO3
+
AuCl3
2.
Classify each of the following reactions as a combination, decomposition,
4 pts single replacement, or double replacement.
Reaction Type
a. BaCl2 (aq) + K2CO3 (aq)
b. NiCl3 (l)
BaCO3 (s) + KCl (aq
Ni (s)
+
Cl2 (g)
c. AuBr (aq) + S (aq)
Au2S (aq) +
d. CO2 (aq)
ZnCO3 (s)
+
ZnO (s)
Br2 (l)
3.
For the following Oxidation/Reduction reactions, show the two half-cells and
8 pts show which element is oxidized and which is reduced.
a.
CaSO3
b.
Pb3N2
c.
Al2O3
d.
CrN
+
+
Fe
FeSO3
FeI3
PbI4
Al
+
O2
+
+
+
Ca
Fe3N2
O2
Cr2O3
+
N2
page 2
4.
8 pts
In the following reaction, sulfur (S) reacts with aluminum chloride (AlCl3) to
produce aluminum sulfide (Al2S3) and chlorine (Cl2) gas.
3 S (s)
+
2 AlCl3 (s)
1 Al2S3 (s)
+
3 Cl2 (g)
Calculate the molar mass for the following molecules.
Show all calculations and units!
4e.
a. S
b. AlCl3
c. Al2S3
d. Cl2
How many grams of AlCl3 are consumed when 2.8 moles of Al2S3 are produced?
8 pts
4f.
If 0.75 grams of S are used, how many grams of AlCl3 are needed?
8 pts
4g.
How many grams of Cl2 is 0.15 moles of Cl2?
8 pts
4h.
With 0.67 moles of AlCl3, how many grams of Al2S3 are produce?
8 pts
page 3
5.
8 pts
6.
16 pts
Calculate the concentration of a solution when a 25 mL sample of
6 M nitric acid solution is diluted to 150 mL?
A solution is prepared by combining 8 g of sodium hydroxide (NaOH)
with 245 g of H2O and the solution has a density of 1.8 g/mL.
a. What is the mass/mass percent of the sodium hydroxide solution?
b. What is the mass/volume percent of the sodium hydroxide solution?
7.
8 pts
Calculate the milliliters of solution needed to prepare a 35% (m/v) NaOH
solution containing 27 g of NaOH.
8.
How many grams of FeCl3 are generated if 125 mL of a 0.85 M BaCl2 solution
8 pts are used in this reaction?
3 BaCl2
+
1 Fe2O3
2 FeCl3
+
3 BaO
page 4
Stoichiometry Practice Quiz
Answer Key
1. What is the molar mass for each reactant and product?
a.
FeCl3
b. BaSO4
1 x Fe = 1 x 56
= 56
3 x Cl = 3 x 35.5 = 106.5
1 x Ba = 1 x 137
1 x S = 1 x 32
4 x O = 4 x 16
162.5 g FeCl3
1 mol FeCl3
c.
= 137
= 32
= 64
233 g BaSO4
1 mol BaSO4
Fe2(SO4)3
d. BaCl2
2 x Fe = 2 x 56
= 112
3 x S = 3 x 32
= 96
12 x O = 12 x 16 = 192
1 x Ba = 1 x 137 = 137
2 x Cl = 2 x 35.5 = 71
400 g Fe2(SO4)3
1 mol Fe2(SO4)3
208 g BaCl2
1 mol BaCl2
2. Balance the equation.
2 FeCl3
+
3
à
BaSO4
1 Fe2(SO4)3
+
3 BaCl2
3. How many moles of Fe2(SO4)3 are produced when 0.0045 mol of BaCl2 are produced?
1 mol Fe2(SO4)3
3 mol BaCl2
ratio
from
chemical
equation
x
0.0045 mol BaCl2
1
=
0.0015 mol Fe2(SO4)3
4. How many moles of Fe2(SO4)3 will be produced when 145 g of BaSO4 react?
1 mol Fe2(SO 4)3
1 mol BaSO4
x
3 mol BaSO4
233 g BaSO4
ratio
from
chemical
equation
145 g BaSO4
x
1
= 0.207 mol Fe2(SO 4)3
given
molar
mass
BaSO4
5. How many grams of Fe2(SO4)3 are produced when 5.6 moles of BaCl2 are produced?
400 g Fe2(SO 4)3
x
1 mol Fe2(SO 4)3
1 mol Fe2(SO 4)3
3 mol BaCl2
5.6 mol BaCl2
x
ratio
from
chemical
equation
molar
mass
Fe2(SO 4)3
= 750 g Fe2(SO 4)3
1
given
6. How many moles of FeCl3 are in 67 grams of FeCl3?
1 mol FeCl3
162.5 g FeCl3
x
67 g FeCl3
=
0.41 mol FeCl3
1
molar
mass
FeCl3
given
7. If 4.6 grams of FeCl3 are used, how many moles of BaSO4 are needed?
3 mol BaSO4
x
2 mol FeCl3
ratio
from
chemical
equation
1 mol FeCl3
162.5 g FeCl3
molar
mass
FeCl3
x
4.6 g FeCl3
1
=
0.042 mol BaSO4
given
8. In this reaction, which element is oxidized and which is reduced?
+
Cr
à
Cr2O3
+
Zn
Zn2+ O2- +
Cro
à
Cr3+ O2-
+
Zno
Zn2+
Cro
à
Cr3+ +
Zno
(remove O2- from both sides)
Zn2+
à
Zno
(gain electrons reduction)
Cro
à
Cr3+
(lose electrons oxidation)
ZnO
+
2