Unit 8 Review Questions
1. If the equilibrium expression for a reaction is Keq=[AC]^5[B]/[A5][C5][B]?
a. A5+BC5=5AC+B
2. What is the equilibrium expression for 3A2+B3=3A2B?
a. Keq=[A2B]^3/[A2]^3[B3]
3. What is the equilibrium expression for the reaction A2(g)+C(s)=A2C(g)?
a. Keq=[A2C]/[A2]
4. What is Keq if the expression is Keq=[NO]^2/[N2][O2] if [NO]=0.1, [N2]=.95, and
[O2]=.95?
a. 0.011
5. What’s the equilibrium expression for O2(s)=O2(g)?
a. Keq=[O2]
1. Explain what Le Chatelier’s principle is.
2. What is stress? List the four types.
3. If the temperature is increased within this system:
N2 + 3H2 ⇌ 2NH3+ Heat
in equilibrium, does the system shift left or right and why?
4. Find the solubility within the system:
NaCl(s) ⇌ Na(aq) + Cl(aq)
given the Ksp of 1.8*10^-3.
5. If the concentration of H2 is increased, does the system shift to the left or right and
why?
H2 + O2 ⇌ H2O2
1. What does collision theory have to do with the rate of reaction?
2. On an endothermic graph, what are the chemicals called at the beginning?
a. Activation energy
b. Reactants
c. ∆H
3. If you add a catalyst to a reaction, what changes to the graph will you see?
4. Why is collision important to a reaction? What will happen if the molecules don’t
collide? (Collision Theory)
5. What differences can you see between an endothermic reaction graph and an exothermic
reaction graph?
1. Which of the following factors does not affect the reaction rate of a reaction?
a. Temperature
2.
3.
4.
5.
b. Pressure
c. Concentration
d. Solubility
e. Volume
What is the overall order of Rate=k[NH4][O2]?
a. 0
b. 2
c. 3
d. 6
What happens to the rate if the concentration of O3 is tripled in Rate=k[NO2][O3]
a. Multiplies by 3
b. Divides by 3
c. Multiplies by 9
d. Divides by 9
If the concentration of A doubles and the initial rate doubles, what is the order of
reaction for A?
a. 0
b. 1
c. 2
d. 3
What is the symbol k in the rate law expression?
ANSWER KEY
:
:
1. If stress is applied to a system at equilibrium, the system shifts in the direction with less
stress.
2. Left because stress is applied onto the right and it must migrate to the left to alleviate the
stress.
3. Stress: any kind of change in a system at equilibrium that upsets equilibrium.
4 types: pressure, temperature, concentration, volume
4. √1.8*10^-3
5. As the reactant, H2, is increased, the other reactant will decrease and the product will
increase, because there is more stress upon the reactants side and the reactants are more
likely to have more collisions. The initial amount of the other reactant, O2, is decreased
because there is not as much of it in relation to H2.
1. Collision theory is used to predict the rate of reactions. It states molecules must collide in
order to react.
2. B, Reactants.
3. If you add a catalyst to a reaction the change in the graph you will see will be the
activation energy will be lower (the hump), providing and easy and quicker pathway for
the reaction.
4. The collision theory is important to a reaction, because if they don’t collide they won’t
react.
5. In an endothermic reaction graph you can see the reactants start lower, and the products
end higher, and in an exothermic reaction graph the the reactants start higher and the
products end lower.
1.
2.
3.
4.
5.
d
b
c
b
The symbol k is the specific rate constant, a numerical value that relates the reaction rate
and the concentrations of reactants at a given temperature. It is unique for every reaction.