2/9/16
Name: ___________
Date: ___________
Chemistry 30 Unit 3 Unit
Assignment Part A – Equilibrium
Note: the following symbol  will represent the double-headed equilibrium arrow.
Complete all work on loose-leaf paper.
1. In a reaction, 4.22 mol of product has formed but there are no more visible signs of
change. Calculations show that as much as 6.00 mol of product could have been formed
from the chemical amounts used. Determine the percent yield and explain where the
equilibrium lies in this reaction (70.3%, right)
Use the following information to answer the next question
Sulfuric acid is the most common commercial acid, with millions of tonnes produced
each year. The second step in the production involves the oxidation of sulphur dioxide
gas catalyzed with V2O5(s),
2SO2(g) + O2(g)  2 SO3(g)
H = -198 kJ
2. a) Set-up the equilibrium law for this reaction.
b) List three stresses that could shift the equilibrium to the products side of the
reaction.
c) If the equilibrium constant, Keq, for the above reaction at a given temperature is
2.4 x 103, what is the constant for the reverse reaction (the decomposition of sulphur
trioxide)?
Use the following information to answer the next two questions
Consider the following reaction to produce hydrogen, done as a first step in the
industrial production of ammonia. Methane (from natural gas) reacts with steam
over a nickel powder catalyst;
CH4(g) + 2H2O(g) + heat  CO2(g) + 4H2(g)
3. The preceding reaction takes place in a stainless steal autoclave (a pressurized reaction
vessel), where it proceeds to equilibrium. More methane is then injected into the
autoclave.
a) According to Le Chatêlier’s Principle, What will happen to the concentration of each
of the species after the methane is injected?
LD Industries
2/9/16
b) Draw a possible concentration/time graph for the adding of methane to the system at
equilibrium.
4. When the reaction is preformed, 0.110 mol/L methane is injected into the autoclave. At
equilibrium, the methane concentration is 0.010 mol/L. What is the concentration of
hydrogen after equilibrium has been reached? (0.400 mol/L)
5. When carbon dioxide gas “dissolves” in water, the process is more correctly thought of
as being an exothermic chemical reaction with water, to form aqueous carbonic acid.
Carbonated soft drinks are produced in this way.
a) Write and balance an equilibrium equation for this reaction.
b) Describe and explain a situation in which a carbonated soft drink is in
i) a non-equilibrium state
ii) an equilibrium state
6. For each of the following descriptions,
i) Write a chemical equation for the system at equilibrium.
ii) Communicate the position of the equilibrium (left, right, etc)
iii) Write the equilibrium law for each chemical system.
a) A combustion of low pressure and high temperature provides a percent yield of less
than 10% for the formation of ammonia in the Haber process.
b) At high temperatures, the formation of water vapour from hydrogen and oxygen is
quantitative.
c) The reaction of carbon dioxide and hydrogen has a percent yield of 67% at 500C.
7. Scientists and technologists are particularly interested in the use of hydrogen as a fuel.
The reaction for the combustion of hydrogen is shown below. Interpret this reaction
equation by predicting the relative proportions of reactants and products in this system at
equilibrium.
2H2(g) + O2(g)  2H2O(g)
Kc = 1 x 1080 at SATP
8. In a container at high temperature, ethyne (acetylene) and hydrogen react to produce
ethene (ethylene). No ethene is initially present. Later, at equilibrium, the concentration
of ethene is 0.060 mol/L.
C2H2(g) + H2(g)  C2H4(g)
a) The initial concentrations of both acetylene and hydrogen are 1.00 mol/L. Determine
the equilibrium constant for this reaction. (0.068)
b) Draw a reaction progress graph to show the change in concentration values over time,
from the beginning of the reaction until equilibrium.
LD Industries
2/9/16
Use the following information to answer the next question.
H2(g) + Br2(g)  2 HBr(g)
Kc = 12.0
at tC
9. a) 8.00 mol of hydrogen and 8.00 mol of bromine are added to a 2.00 L reaction flask.
Calculate the concentrations of all species at equilibrium. (5.07)
b) 12.00 mol of hydrogen and 12.00 mol of bromine are added to a 2.00 L reaction
flask. Calculate the concentrations of all species at equilibrium. (7.60)
Use the following information to answer the next question.
CO(g) + H2O(g)  CO2(g) + H2(g)
Kc = 4.00 at 900C
10. In a container, carbon monoxide and water vapour react to form carbon dioxide and
hydrogen. The equilibrium concentrations are:
[H2O(g)] = [H2(g)] = 2.00 mol/L.
[CO2(g)] = 4.00 mol/L
Determine the equilibrium concentration of carbon monoxide. (1.00)
11. At a temperature of 300°C and a pressure of 40.5 MPa, 90.0 mol of H2(g) and 80.0 mol
of N2(g) are injected into a reaction vessel. When equilibrium is established, 37.0 mol of
NH3(g) are present. The number of moles of H2(g) present in this equilibrium mixture is
__________ mol. (34.5)
12. Predict the shift in the following equilibrium system resulting from each of the
following changes:
4HCl(g) + O2(g)  2H2O(g) + 2Cl2(g) + 113 kJ
a) An increase in temperature to the system.
b) A decrease in the systems total pressure.
c) An increase in the concentration of oxygen.
d) The addition of a catalyst.
e) An increase in total volume of the system.
13. Chemical engineers use Le Chatêlier’s principle to predict shifts in chemical system
at equilibrium resulting from changes in reaction conditions. Predict the changes needed
to maximize the yield of product in each of the following industrial chemical systems:
a) the production of ethene (ethylene)
C2H6(g) + energy  C2H4(g) + H2(g)
b) the production of methanol
CO(g) + 2H2(g)  CH3OH(g) + energy
LD Industries