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Chemical Equilibrium 1

Total questions: 20

Worksheet time: 12mins

Name
Class
Date
1.

This symbol indicates that a reaction is ____________

a)

reversible

b)

irreversible

c)

constant

d)

same rate

2.
When the rate of the forward reaction is equal to the rate of backward reaction, the system is said to be in
a)
Chemical Equilibrium
b)
Chemical Balance
c)
Stoichiometry
d)
Chemical Reaction
3.
At what time the reaction reached equilibrium?
a)
t1
b)
t2
c)
t3
d)
t4
4.

At elevated temperatures ammonium carbonate, NH2COONH4, is in equilibrium with NH3 and CO2 according to the equation;

NH2COONH4(s) ↔ 2 NH3(g) + CO2(g)

What is the equilibrium expression for this reaction?

a)

K = 2 [NH3][CO2]

[NH2COONH4]

b)

K = [NH3]2[CO2]

[NH2COONH4]

c)

K = 2 [NH3][CO2]

d)

K = [NH3]2[CO2]

5.

What kind of equilibrium does the reaction below show?

H2(g) +I2(g) ↔ 2HI(g)

a)

Heterogeneous equilibrium, all the reactants and products are in the same physical state.

b)

Homogeneous equilibrium, all the reactants and products are in the same physical state.

c)

Heterogeneous equilibrium, the reactants and products are present in more than one physical state

d)

Homogeneous equilibrium, the reactants and products are present in more than one physical state

6.
What are the two factors to look for when determining if the reaction is at equilibrium?
a)
Forward reaction rate is faster than the reverse and concentrations are equal
b)
Forward and reverse reaction rates are equal and concentration is conctant
c)
Forward and revers reaction rates are equal and concentration is equal
d)
Forward reaction rate is faster than the reverse and concentration is equal
7.

Identify the incorrect statement about achieving equilibrium.

a)

achieved when product and reactant concentrations are equal

b)

achieved when forward and reverse reaction rates are same

c)

achieved when concentration of reactants is stable/constant

d)

achieved when concentration ratio of reactants to products becomes stable, thus fixing the equilibrium constant (equilibrium position)

8.
2A + 3B  <---->  2AB
The forward reaction points towards the __________.
a)
left
b)
right
c)
up
d)
down
9.
Identify the labels (a) and (b) on the graph.
a)
a is concentration of reactants and b is the concentration of product
b)
a is concentration of product and b is the concentration of reactant
c)
a is the volume of reactants and b is the volume of product
d)
a the mass of reactants and b is the mass of product
10.
Which of the two graphs reaches equilibrium?
a)
The left one.
b)
The right one.
c)
Both of them.
d)
Neither.
11.
Which of the following is NOT true at equilibrium?
a)
The forward and reverse reactions proceed at the same rate.
b)
The concentrations of reactants and products do not change.
c)
The concentration of the reactants is equal to the concentration of the products.
d)
The forward and reverse reactions continue to occur.
12.

What kind of equilibrium does the reaction below show?

H2(g) +I2(g) ↔ 2HI(g)

a)

Heterogeneous equilibrium, all the reactants and products are in the same physical state.

b)

Homogeneous equilibrium, all the reactants and products are in the same physical state.

c)

Heterogeneous equilibrium, the reactants and products are present in more than one physical state

d)

Homogeneous equilibrium, the reactants and products are present in more than one physical state

13.
Which is the reactant - and why?
a)
A, as concentration decreases
b)
B, as concentration decreases
c)
A, as concentration increases
d)
B, as concentration increases
14.
When the system X + 2 Y <=> Z has reached equilibrium, which of the following is TRUE?
a)
Forward reaction and Backward reaction stop.
b)
Forward reaction has sped up and backward reaction has slowed down.
c)
Forward and backward reactions occur at the same rate.
d)
Forward reaction has slowed down and backward reaction has sped up.
15.
What are [A] and [B]?
a)
concentration of reactants
b)
concentration of products
c)
energy of reactants
d)
energy of products
16.
What is the Kc expression for this reaction?
   2 NO(g)  +  O2(g) ⇌  2 NO2(g)
a)
K= [NO2]2 / [NO][O2]
b)
K=  [NO][O2] / [NO2]2
c)
K= [NO][O2] [NO2]2
d)
K= [NO2]2 / [NO]2 +  [O2]
17.

The Kc expression for the reaction 2NH3 (g) ⇌ N2 (g)+ 3H2(g)

a)
b)
c)
d)
18.

Why is equilibrium called a dynamic state?

a)

Chemists try to convert as much reactants as possible into products.

b)

The reactions at equilibrium continue to take place once equilibrium is established.

c)

The products of a forward reaction are favored, so equilibrium lies to the right.

d)

All chemical reactions are considered to be reversible under suitable conditions.

19.

At what time (in seconds) is equilibrium established?

a)

0 second

b)

1 second

c)

5 seconds

d)

10 seconds

20.

A complete reaction is in which:

a)

All the reactants convert into products

b)

All the reactants do not convert into products

c)

Half reactants convert into products

d)

only 10% reactants convert into products