chemical equillibrium

Question 1

_______ is a chemical reaction that result in an equilibrium mixture of reactants and products

Answer 1

reversible reaction

Question 2

state an example of a reversible reaction

Answer 2

the formation of ammonia
formation of hydrogen iodide from hydrogen gas and iodine vapours

Question 3

______ are chemical reactions that only proceed in one direction

Answer 3

Irreversible reactions

Question 4

what sign is used to indicate an irreversible reaction?

Answer 4

a single arrow

Question 5

what sign is used to indicate a reversible reaction?

Answer 5

a double arrow

Question 6

the reaction from the reactant side to the product side is known as _____

Answer 6

forward reaction

Question 7

the reaction from the product side to the reactant side is known as ________

Answer 7

reverse reaction

Question 8

true or false. the equillibrium is dynamic

Answer 8

True, although at the macroscopic level the properties do not change with time, at the molecular level the two processes are still taking place

Question 9

________ is a solution in which undissolved solute is in equilibrium with the solute being dissolved in the solution

Answer 9

Saturated solution

Question 10

an equilibrium involving a chemical reaction is known as _________

Answer 10

chemical equilibrium

Question 11

define chemical equilibrium

Answer 11

it is a state of the reaction when the macroscopic properties like temperature, pressure, volume and concentration of reactants do not change with time

Question 12

the rate of forward reaction depends upon _________

Answer 12

the concentration of reactants

Question 13

the rate of reverse reaction depends upon _________

Answer 13

the concentration of products

Question 14

true or false. Chemical equilibrium can be obtained only from a forward reaction.

Answer 14

False, it can also be obtained from a reverse reaction

Question 15

True or False
the concentration of reactants and products are not necessarily equal at an equilibrium

Answer 15

True, only the rate of forward and reverse reaction are equal

Question 16

list some characteristics of a chemical equilibrium

Answer 16

rate of forward and reverse reaction is equal
reaction takes place in a closed vessel
all reactants and products are present at equilibrium
the macroscopic properties like temperature, volume, pressure and concentration do not change with time
it is dynamic in nature
equilibrium can be obtained from either side
free energy change of the reaction is zero at equilibrium

Question 17

state the law of mass action

Answer 17

1. the combining power of two reactants A and B depends upon their nature as well as their active concentrations.
   2.The rate at which A and B combine is directly proportional to the product of their concentration terms each raised to the power of its respective coefficient in the balanced chemical reaction

Question 18

name the chemists who devised the law of mass action.

Answer 18

Peter Waage and C.M. Guldberg

Question 19

True or False
when writing the equilibrium constant, the concentration of all the substances formed as products are written in the numerator

Answer 19

True
Kf/Kb =[M]^m[N]^n/[A]^[B]^b for a reaction
aA + bB = nN +mM

Question 20

True of False
thermal decomposition of calcium carbonate is an example of homogeneous reaction

Answer 20

False, it is a heterogeneous reaction

Question 21

what different rule do we follow when writing the equilibrium constant for a heterogeneous reaction?

Answer 21

Only the gaseous state reactants and products will be written.

Question 22

According to
the ideal gas equation, the partial pressure (p) is given by

Answer 22

p = nRT / V and n/V = C

where n = amount of the gaseous species in moles
R = Gas constant
C=molarity
T= temperature in kelvin

Question 23

what does the equilibrium constant indicate when it is greater than 1?

Answer 23

Case 1: When Kc>1
it indicates that the numerator is bigger than the denominator. Thus, the formation of product is favored more

Question 24

what does the equlibrium constant indicate when it is lower than 1?

Answer 24

Case 2: When Kc<1
This indicates that the value of numerator is less than the denominator.
So the formation of products is not favored at equilibrium.

Question 25

what does the equilibrium indicate when it is equal to 1?

Answer 25

Case 3: When Kc=1
This indicates that the rate of forward reaction is equal to the rate of backward
reaction

Question 26

True or False,
Very large values of Kc indicates that the extent of the reaction is very large at equilibrium

Answer 26

True
this shows that most of the reactants will be consumed at equilibrium

Question 27

what would the equlilbrium constant indicate about the extent of reaction if it was very small?

Answer 27

it indicates that the extent of reaction is very small at equilibrium. So, most of
the reactants will be in the unreacted state

Question 28

_____________ is the ratio of concentrations of products to the concentrations of
reactants raised to the power of their respective coefficients at any stage after the start
of the reaction

Answer 28

Reaction quotient

Question 29

at the initial stage the value of the reaction quotient will be ______.
A)small
B)big
C)constant
D)zero

Answer 29

A) small,
this is because the reactants in the denominator have yet to be reacted, so the products in the numerator are small.

Question 30

When the reaction attains equilibrium, Q
becomes equal to the _______________

Answer 30

equilibrium constant

Question 31

what happens when the reaction quotient is less than the equilibrium constant?

Answer 31

the reaction will proceed in the forward direction and more products will be formed till the equilibrium is reached.

Question 32

what happens when the reaction quotient is greater than the equilibrium constant?

Answer 32

the reaction will proceed in the reverse direction and more reactant will be formed till the equilibrium is reached

Question 33

true or false
When Q is equal to K, then the reaction has attained equilibrium.

Answer 33

true

Question 34

what factors affect the equilibrium constant?

Answer 34

temperture and the form of equation

Question 35

state the four reaction parameters

Answer 35

temperature
concentration
pressure
volume

Question 36

__________ principle describe the changes that will take place when
any one of the reaction parameters are changed at equilibrium

Answer 36

Le Chatelier’s

Question 37

true or false
According to Le Chatelier’s principle, if the temperature of the reaction at equilibrium
is increased then the reaction will proceed in that direction where heat is absorbed so
as to undo the effect of heating

Answer 37

true

Question 38

which favors the forward reaction in an exothermic reaction? increasing or decreasing temperature.

Answer 38

Decreasing

Question 39

which direction will the reaction proceed if the pressure is increased?

Answer 39

in the direction where the pressure will be reduced

Question 40

True or False
If ∆n > 0, Lowering of pressure will favour the reaction in reverse direction.

Answer 40

false. if change in n is greater than zero, it means moles of products is bigger than the moles of reactant. lowering the pressure will favor the creation of products, meaning the forward reaction.