SCH4U: End of Year Review
Unit 1: Energy and Rates
1)
W hen 13.4 g of am m onium chloride dissolve into 2.00x102 g of water the tem perature changes
from 20.0o C to 15.3o C. Determ ine the m olar enthalpy of solution of am m onium chloride, write a
balanced therm ochem ical equation for the reaction and sketch an enthalpy diagram for this
reaction. (Ans: +15.7 kJ/m ol)
2)
The following chem ical reaction occurs in a car battery:
Pb(s) + PbO 2 (s) + 2H 2 SO 4 (aq) Y 2PbSO 4 (s) + 2H 2 O(l)
a) Given the following enthalpy of form ation values, calculate the enthalpy of reaction for the
above reaction
PbO 2 (s)
= -227 kJ/m ol
PbSO 4 (s)
= -920.1 kJ/m ol
H 2 SO 4 (aq)
= -909.3 kJ/m ol
H 2 O(l)
= -285.5 kJ/m ol
Answer
= -365.6 kJ
b) If it takes 39.5 kJ to start your car, what m ass of lead (II) sulphate is produced when starting the
car? (Ans: 65.5 g)
3)
The com bustion of ethane is illustrated by the following equation:
2C 2 H 6 (g) + 7O 2 (g) Y 4CO 2 (g) + 6H 2 O(g)
a)
Show how the following equations can be com bined using Hess’s Law to determ ine the
enthaly of com bustion of ethane (Ans: -3028 kJ)
1) C 2 H 4 (g) + 3O 2 (g) Y 2CO 2(g) + 2H 2O(g)
ÄH = -1409 kJ
2) C 2 H 4 (g) + H 2 (g) Y C 2 H 6 (g)
ÄH = -136.7 kJ
3) H 2 (g) + ½ O 2 (g) Y H 2 O(g)
ÄH = -241.6 kJ
b)
4)
If you wish to burn ethane as a fuel to heat 550.0 g of water from 12.5 o C to 100.0 o C, how
m any m oles of ethane will be required? (Ans: 0.13 m ol)
Page. 414-416 in your text: Questions: 13, 14, 15, 16, 18
Unit 2: Chemical Equilibrium
a)
Introduction to Equilibrium
1)
From your text: Page 457 Questions: 1-4, Page 465 Questions: 1,2 page 481 Questions: 1-8
b)
Solubility Equilibrium
1)
Consider the following salts (text Ksp table : pg. 802)
a)
b)
List these salts in order of increasing solubility.
W rite the chem ical equilibrium equation for the form ation of an aqueous solution of the least
soluble silver salt.
Determ ine the solubility in m ol/L and in g/L for the least soluble silver salt.
(Ans:9.2x10 -9 m ol/L, 2.2x10 -6 g/L)
Determ ine the solubility in m ol/L of the least soluble silver salt in a solution containing 0.025 M
NaI(aq). (Ans: 3.4x10 -15 m ol/L)
AgI
c)
d)
2)
AgNO 3
AgCl
Ag 2 CO 3
Ag 2 CrO 4
You are given a 100.0 m L sam ple of 0.0010 M silver nitrate solution and a sodium carbonate
(Na 2 CO 3 ) prepared by dissolving 6.4x10-4 g of sodium carbonate in water to form 100.0 m L of
solution. If the two solutions are m ixed at 25o C, will a precipitate of silver carbonate form ?
(Ans: Kt = 7.5x10 -12 )
-2c)
Acid/Base Equilibrium
1)
Determ ine the pH of the following: (a) 0.025 M KOH solution. (b) 0.075 M HNO 3 solution
(ANS: a) pH 12.4 b) pH 1.1)
2)
a)
b)
Nicotinic acid is a weak m onoprotic organic acid with the form ula C 6H 4NCOOH.
W rite the equilibrium equation for nicotinic acid in water.
If a 0.050 M solution of nicotinic acid has a pH of 3.1, determ ine the Ka of this acid.
(ANS: 1.3x10 -5 )
3)
Consider the following salts:
KNO 3
LiC 6 H 5 COO
N 2 H 5 Cl
LiCN
NH 4 I
a)
b)
Group the salts into the following categories: i) neutral salts, ii) acidic salts, iii) basic salts
For the salts that you classified as “acidic” or “basic” write the equilibrium reaction that will explain
this property.
4a)
W hat volum e of 0.0150 M HNO 3 is needed to titrate 30.0 m L of 0.0250 M NaOH to the
equivalence point? W hat will the pH be at this point? (ANS: 50.0 m L, pH 7)
Determ ine the pH of the solution after adding 49.5 m L of HNO 3 (ANS: pH 9.97)
Determ ine the pH of the solution after adding 50.5 m L of HNO 3 (ANS: pH 4.03)
4b)
4c)
5)
a)
b)
6)
a)
b)
c)
Hydrosulphuric acid is a weak acid with a Ka = 9.1x10 -9
H 2 S + H 2 O W H 3 O + + HS Determ ine the pH of a 0.075 M solution of this acid. (ANS: pH 4.6)
W hat is the percent dissociation of this acid? (ANS: 0.035%)
Hydrocyanic acid is a weak acid with a Ka = 4.9x10 -10
HCN + H 2 O W CN - + H 3O +
Determ ine the pH of a buffer solution prepared using 0.25 M HCN and 0.010 M NaCN.
(ANS: pH 7.9)
W hat is the Kb of the cyanide ion? (ANS: Kb= 2.0x10 -5 )
Determ ine the pH of a 0.15 M NaCN solution. (ANS: pH 11.2)
Unit 3: Atomic Structure and Classification of Solids
1)
Describe the contributions of the following scientists to our current understanding of atom ic
structure and the quantum theory:
a) Bohr
b) DeBroglie
c) Heisenberg d) Schrodinger
e) Pauli
2)
Based on the quantum m echanical m odel of the atom :
a) W hat is an “orbital”?
b) W hat is the m axim um electron carrying capacity of the following energy levels: n=2, n=4
c) Describe the sublevel and orbital structure of the following energy levels: n=2, n=4
3)
a) W rite the energy level diagram for a neutral atom of nitrogen.
b) Assign the quantum num bers to each of the electrons in your nitrogen atom .
4)
W rite the electron configuration for the following: a) a neutral atom of cobalt, b) an Fe 2+ ion
-35)
Use Lewis diagram s to draw the following m olecules or ions. Once com pleted, use the VSEPR
Theory to predict the shape of each. For each m olecule, decide whether it is polar or non-polar.
a) PCl 3
b) SiF 4
c) CO 3 2d) H 2 S
e) XeCl4
3f) PO 4
g) O 3
h) CO
i) NO 3 1j) SF 4
6)
Methane and fluorom ethane are two very sim ilar m olecules, despite their sim ilarities, there is an
86o C difference between their boiling points. W hich of these two substances would have the
higher boiling point, explain your answer.
7)
The elem ent iodine exists as solid crystals com posed of I 2 m olecules. A chem ist wishing to
dissolve iodine has a choice of two solvents; water and tetrachlorom ethane. W hich of these two
solvents would be the best choice? Explain your answer.
8)
Consider a m olecule of ethanal.
a) W hat type of orbital hybridization is each atom in the m olecule using for bonding?
b) W hat geom etric arrangem ent would each of these orbitals take?
c) Describe the orbital overlap that accounts for each bond, and specify the type of bond form ed
(sigm a, pi)
d) W hat are the bond angles around each carbon atom in this m olecule?
9)
Consider the data in the following table for substances labelled “A” to “G”
Substance
Melting point (o C)
Boiling point (o C)
Solubility in H 2O
Electrical
conductitvity as:
solid/liquid/aq. sol.
SOLUBLE
NO/NO/NO
A
-94
65
B
1610
2230
INSOLUBLE
NO/NO/NA
C
119
445
INSOLUBLE
NO/NO/NA
D
660
2467
INSOLUBLE
YES/YES/NA
E
770
1500
SOLUBLE
NO/YES/yes
F
-182
-164
INSOLUBLE
NO/NO/NA
G
2614
2850
slightly SOLUBLE
NO/YES/slightly
a)
Classify each substance as to the type of solid it represents (ie; m olecular, m etallic, ionic, network)
b)
The substances labeled “A” to “G” above are identified in random order below. Match the letter to
the correct nam e and explain your reasoning.
Quartz, calcium oxide, alum inum , m ethanol, sulphur, m ethane, potassium chloride
-4Unit 4: Organic Chemistry
1)
Draw the structural form ula for the following com pounds:
a) N,N-dim ethyl-2-pentanam ine
b) 3-ethylcyclohexene
d) 4-chloro-3-m ethyl-1-hexyne
e) 2-ethoxypropane
g) N-ethylpropanam ide
h) 2,3-difluorobutanoic acid
j) 2-m ethyl-3-hexanol
k) phenyl m ethanoate
c) m ethylpropanal
f) propylbenzoate
i) cyclobutanone
l) 2,4-hexadiene
2)
Nam e the following organic com pounds:
3)
Com plete the following chem ical reactions by nam ing and drawing the m olecular form ula the
organic product(s). Assum e all required conditions are available for each reaction.
a)
c)
e)
g)
4)
3-m ethyl-1-butyne + 2Cl 2
2-m ethyl-3-pentanol + KMnO 4
2-m ethylbutanal + KMnO 4
dim ethyl-1,3-propandiol + KMnO 4
b)
d)
f)
h)
m ethane + excess O 2
m ethylpropene + HBr
cyclopentene + H 2O (H 2SO 4 catalyst)
ethanoic acid + phenol
Consider the following organic com pounds:
propanone, 2-propanol, 2-chloropropane, propanoic acid, propane
a) For each com pound, identify the type of interm olecular forces acting between m olecules
b) Rate the solubility of each com pound in water as: insoluble, slightly soluble or very soluble
c) Arrange the com pounds in order of increasing boiling point.
-5Unit 5: Electrochemistry
1)
Consider the following electrochem ical cells. For each, write the correct oxidation and reduction
half-reactions and determ ine the overall cell reaction and the standard cell potential. Identify the
cathode and anode in each cell.
A) Zn*Zn2+ 2Cl 2 *Cl(ANS: E c ell= (A) 2.12 V
2)
B) Pb*Pb 2+ 2Na*Na +
(B) 2.58 V
C) Au*Au 3+ 2Ag*Ag +
(C) 0.70 V)
Draw and label a diagram of the following electrochem ical cell. Include in your diagram a salt
bridge, label each electrode, show the direction of electron flow determ ine the overall cell reaction
and calculate the standard cell potential. (ANS: E c ell= 3.18V)
Mg*Mg 2+ 2Ag*Ag +
3)
Balance the following redox reactions by the m ethod indicated:
b)
half-reaction m ethod in acidic solution:
MnO 4 - + H 2 C 2 O 4 W Mn 2+ + CO 2
a)
half-reaction m ethod in basic solution:
Cr(OH) 63- + BrO 1-
c)
º CrO 42-
oxidation num ber m ethod:
K + KNO 3 W N 2 + K 2 O
+
Br 1-