chemical equillibrium Flashcards
_______ is a chemical reaction that result in an equilibrium mixture of reactants and products
reversible reaction
state an example of a reversible reaction
the formation of ammonia
formation of hydrogen iodide from hydrogen gas and iodine vapours
______ are chemical reactions that only proceed in one direction
Irreversible reactions
what sign is used to indicate an irreversible reaction?
a single arrow
what sign is used to indicate a reversible reaction?
a double arrow
the reaction from the reactant side to the product side is known as _____
forward reaction
the reaction from the product side to the reactant side is known as ________
reverse reaction
true or false. the equillibrium is dynamic
True, although at the macroscopic level the properties do not change with time, at the molecular level the two processes are still taking place
________ is a solution in which undissolved solute is in equilibrium with the solute being dissolved in the solution
Saturated solution
an equilibrium involving a chemical reaction is known as _________
chemical equilibrium
define chemical equilibrium
it is a state of the reaction when the macroscopic properties like temperature, pressure, volume and concentration of reactants do not change with time
the rate of forward reaction depends upon _________
the concentration of reactants
the rate of reverse reaction depends upon _________
the concentration of products
true or false. Chemical equilibrium can be obtained only from a forward reaction.
False, it can also be obtained from a reverse reaction
True or False
the concentration of reactants and products are not necessarily equal at an equilibrium
True, only the rate of forward and reverse reaction are equal
list some characteristics of a chemical equilibrium
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
state the law of mass action
- 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
name the chemists who devised the law of mass action.
Peter Waage and C.M. Guldberg
True or False
when writing the equilibrium constant, the concentration of all the substances formed as products are written in the numerator
True
Kf/Kb =[M]^m[N]^n/[A]^[B]^b for a reaction
aA + bB = nN +mM
True of False
thermal decomposition of calcium carbonate is an example of homogeneous reaction
False, it is a heterogeneous reaction
what different rule do we follow when writing the equilibrium constant for a heterogeneous reaction?
Only the gaseous state reactants and products will be written.
According to
the ideal gas equation, the partial pressure (p) is given by
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
what does the equilibrium constant indicate when it is greater than 1?
Case 1: When Kc>1
it indicates that the numerator is bigger than the denominator. Thus, the formation of product is favored more
what does the equlibrium constant indicate when it is lower than 1?
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.
what does the equilibrium indicate when it is equal to 1?
Case 3: When Kc=1
This indicates that the rate of forward reaction is equal to the rate of backward
reaction
True or False,
Very large values of Kc indicates that the extent of the reaction is very large at equilibrium
True
this shows that most of the reactants will be consumed at equilibrium
what would the equlilbrium constant indicate about the extent of reaction if it was very small?
it indicates that the extent of reaction is very small at equilibrium. So, most of
the reactants will be in the unreacted state
_____________ 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
Reaction quotient
at the initial stage the value of the reaction quotient will be ______.
A)small
B)big
C)constant
D)zero
A) small,
this is because the reactants in the denominator have yet to be reacted, so the products in the numerator are small.
When the reaction attains equilibrium, Q
becomes equal to the _______________
equilibrium constant
what happens when the reaction quotient is less than the equilibrium constant?
the reaction will proceed in the forward direction and more products will be formed till the equilibrium is reached.
what happens when the reaction quotient is greater than the equilibrium constant?
the reaction will proceed in the reverse direction and more reactant will be formed till the equilibrium is reached
true or false
When Q is equal to K, then the reaction has attained equilibrium.
true
what factors affect the equilibrium constant?
temperture and the form of equation
state the four reaction parameters
temperature
concentration
pressure
volume
__________ principle describe the changes that will take place when
any one of the reaction parameters are changed at equilibrium
Le Chatelier’s
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
true
which favors the forward reaction in an exothermic reaction? increasing or decreasing temperature.
Decreasing
which direction will the reaction proceed if the pressure is increased?
in the direction where the pressure will be reduced
True or False
If ∆n > 0, Lowering of pressure will favour the reaction in reverse direction.
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.
