Ch 17 & 18:
Reaction Rates & Chemical Equilibrium Review
Name:_______________________
Date _______________ Period ___
1) State/Define: a) rate of a reaction
b) Activation energy
c) activated complex/transition state
d) Catalyst
e) Le Chatelier's Principle
2) The products in a reaction have a total heat content of 458 KJ/mol and the reactants have a total heat content
of 658KJ/mol
a) What is the value of heat of reaction? ________
b) Is this reaction exothermic or endothermic? _______________
c) Which is the more stable part of this system, the reactants or the products? _________
3) Label the following reactions as exothermic or endothermic and sketch a rough P.E diagram to illustrate this.
a) N2 + O2 + 187 KJ Æ 2NO __________
b) N2 + 3H2 Æ 2NH3 + 92KJ ___________
4) For a gaseous system at constant temperature, how does pressure influence the reaction rate?
5) Limestone ( calcium carbonate) reacts with Hydrochloric acid in the following reaction:
CaCO3(s) + 2 HCl (aq) Æ CaCl2 (aq) + CO2(g) + H2O(l)
Do the following increase or decrease the reaction rate:
_________ a) the temperature is lowered
_________ b) the volume of the reaction vessel is reduced
_________ c) limestone chips are used instead of a block of limestone.
_________ d) a more dilute solution of HCl is used.
_________ e) a catalyst is used.
6) True or False. When a catalyst is added:
a) the activation energy changes. ____
b) the heat of reaction changes. _______
c) the rate of forward reaction increases while that of reverse reaction decreases. _____
d) the equilibrium shifts either to the left or right.______
7)
Draw a reaction energy diagram for a reaction starting at 0
kJ/mol with an activation energy of 100.0 kJ/mol and a H of
25.0kJ/mol. Label the energy levels of the reactants and
products, the activation energy, and the H.
8) Consider the reaction : 2 H2 + O2 ↔ 2 H2O + 285 kJ. This reaction (endothermic / exothermic) is
____________ in the forward direction but (endothermic / exothermic) ________________ in the reverse
direction.
9) For the reaction, A + B Æ AB, the activation energy for the forward reaction is 85KJ/mol and the activation
energy for the reverse reaction is 80KJ/mol.
a) Which side has greater energy content, the reactants or products? ___________
b) What is the heat of reaction in the forward direction? ________
c) Heat of reaction in the reverse direction is equal in magnitude but opposite in sign to the heat of
reaction in forward direction. True or Flase? ______
10)
Answer the following questions based on the potential energy
diagram shown here:
a) Label the postion of the reactants, products, and activated complex.
b) Determine the heat of reaction, ∆H,for the reverse reaction.
c) Determine the activation energy, Ea for the forward reaction.
d) (T/F) Activation energy is required to initiate only the forward
reaction?
e) How much energy is required for the reverse reaction to occur?
f) How much energy is released or absorbed during the forward
reaction?
g) Does the graph represent an endothermic or exothermic reaction in
the forward direction?
11)
This is the potential energy diagram for the catalyzed and the
uncatalyzed reaction.
a) Which curve represents catalyzed reaction? _____
b) Which curve has greater activation energy or is it the same
for both curves? ______
c) Which curve has greater heat of reaction or is it the same for
both curves? _______
12)
4HCl(g) + O2(g) + heat  Æ 2Cl2(g) + 2H2O(g)
A. Write the equilibrium expression for the following reaction.
Keq =
B. State if the equilibrium position of this reaction shifts to the left or right or remains the same by the
following changes:
a) adding Cl2
b) removing O2
c) increase in pressure
d) adding a catalyst
e) adding H2O gas
f) increasing the temperature
C. An increase in concentration of HCl will __________ the concentration of Cl2 and at the same time
____________ the concentration of O2
13) Consider the following reaction: H2O(g) + Cl2O(g)
2 HClO(g)
Keq = 0.0900 at 25°C
H = 3.00 kcal
A. Does the equilibrium favor products or reactants at 25°C?
B. If temperature remains constant and the pressure increases, the # of moles of HClO(g)
will increase, decrease or remain the same?
C. Would the equilibrium shift in the favor of reactants (left) or products (right) if:
a. The temperature was lowered?
b. H2O (g) was added to the reaction mixture?
c. The volume was increased?
d. HClO (g) was removed from the reaction mixture?
e. The pressure was increased?
14) The reaction below is at equilibrium. Match the stress on the left with the change in position of
equilibrium on the right.
Heat + Co2+(aq) + 4Cl¯ (aq)
CoCl4 2- (aq)
2CoCl4 ion is removed. _____
Chloride ions are added. _____
A. shift to the left
Cobalt ions are removed. _____
B. shift to the right
The reaction is heated.
_____
C. no shift
A catalyst is added.
_____
15) Explain how the following changes in reaction conditions will affect the position of the equilibrium below, and
explain your reasoning.
A(g) + B(aq) ÅÆ C(s)
∆Hrxn= - 453 kJ/mol
a) The pressure of A in the reaction chamber is increased.
b) The temperature of the reaction is increased by 200 C.
c) A catalyst is added to the system.
d) As the reaction progresses, more of compound B is steadily added to the reaction chamber.
e) Argon gas is added to the reaction chamber, doubling the pressure.
OTHER REVIEW STUFF
16) Balance the following equation: _____ Al2O3 + _____ Fe Æ _____ Fe3O4 + _____ Al
a) Describe the type of reaction ________________________
b) Determine the Fe:Al2O3 mole ratio ___________________
c) What is the mass of Fe3O4 produced when 154 g of Fe is completely consumed?
d) How many moles grams of Al will be produced if you use 5g of Fe?
17) When 150 J of energy is lost from a 25g object, the temperature decreases from 65°C to 40°C. What is the
specific heat of this object?
18) How many kJ of energy are required to be absorbed by 165g of water when it is heated from 65°C to 90°C?
19) Find the molarity of a solution containing 69 g Al(OH)3 in 500 ml water.
20) How many liters of a 12.0 M HCl solution would contain 3.00 moles of HCl?
21) A 500 ml volume of helium gas is at a pressure of 750 mm Hg and has a temperature of 30 oC. What is the
volume of the same gas at STP?
22) If the pressure exerted by a gas at 25°C in a volume of 0.044L is 3.81 atm, how many moles of gas are
present?
23) For the a) Cadmium and b) Rb+1 figure out the:
# of protons
Family name
lewis dot diagram
# of neutrons
electron configuration
# of electrons
valence electrons
24)
Chemical name Ionic/Covalent
1. KF
3. CoBr2
4. P205
5.Fe2O3
Compound containing
Transition metal & halogen
(9)
Compound containing Alkali
metal & halogen
(9)