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Sn
NEET 2024 m)
Cou IBRIUN
DIKSHA To
Introduction
e Equilibrium is a state in which there are no observable changes as
time goes by.
e When a chemical reaction has reached the equilibrium state, the
concentrations of reactants and products remain constant over time
however, there is much activity at the molecular level
5 | v
0 ange incthe val.
Capote
| h+B— ai
Alen e neg” ya b e
Conca cowtant
tow =a Same ( (rra)
A+B = Crp
Rate q {un ward Run (RP)
= Rate e) hackuward Pe
(P+ R)
At ey" Conc" = Comtt
N) may | meg net same.
Rale= Same
S gmatant
(ey :
+ Fa
(a, (“y mt) J (b)
+ q" + m
(a) not hue Ww Y
Types of chemical reactions
Irreversible reaction Reversible reaction
Reaction which proceeds in forward | Reaction which proceed in forward
direction only as well as backward direction
PLU,
Attain the equilibrium state and
DS not attain equilibrium state never go to completion
Generally thermal dissociation are Generally thermal dissociation are
held in open vessel held in closed vessel
2KCIO, (s) — 2KCI (s) + 30, (9) PCI, (g) = PCI, (g) + Cl, (9)
Equilibrium in physical process is Equilibrium in chemical
called physical equilibrium. process is called chemical
For example equilibrium.
Phase changes like : For example
H,0(1) + H,0(g) H,(g) + CI,(g) + 2HCI(g)
Solvation :
NaCl(s) _H,0. NaCl(aq)
excess
Types of equilibria on the basis of physical state
Types of equilibria on the basis of physical state
MC y
Homogeneous equilibrium Heteroyeneous equilibrium
When all reactants and products are When more than one phase are
in same phase present
H,(g) + Cl,(g) + 2HCI(g) 3Fe(s) + 4H,0(g) + Fe,0,(s) + 4H,(9)
e As soon as P, and P, are formed, they start the backward reaction. As
concentrations of R, and R, decrease rate of forward reaction decreases
and rate of backward reaction increases.
At equilibrium :
e Rate of forward reaction (r,) = rate of backward reaction (r,)
e All measurable parameters become constant with respect to time.
ah+bB = cc+dD
nok, Caley | #4 i
Ap= Ep UND) se ap ld ul
Re Be cm?
ep
Ke= ne
MOT
Characteristics of chemical Equilibrium
e Itisald ic equilibrium)- at this stage, reaction take place in both
the direction with same speed so., there is no net change
ya equilibrium the reaction proceeds both the side , equally.
X= .
Equilibrium can be obtained from either side of the reaction.
YL catalyst an alter the rate of approach of equilibrium but does not
change the state of equilibrium
SN equilibrium, free energy change(AG =0 ) OS=0 , Aw +0
Equilibrium state can be affected by altering factors like pressure,
volume, concentration and temperature etc.(Le chatelier's Principle)
Law of mass action
[By Guldberg and Waage]
e Active Mass = Molar concentration i.e. Moles/ Litres
Active Mass =
It is represented in square brackets i.e. [] e.g. [A], [N,] etc.
#ote : Active masses ard dimensionless quantities but for our purposes we
generally take them with dimensions of molarity, partial pressure,\etc.
K, (Equilibrium constant in terms of partial pressure)
e Relation between Kp and Kc :
An = sum of the number of moles of
gaseous products - sum of the number of
moles of gaseous reactants
e Unit of k, = (mol/L) 2%
e Unit of k, = (atm)*™
Given the reaction between 2 gases represented by A, and B, to give
the compound AB(¿)" ~~
A, = 3.0 x 107? M, of B, = 4.2 x 107? M, of AB = 2.8 x 107? M
If the reaction takes place in a sealed vessel at 527°C, then the value of
NEET 2012
Given the reaction between 2 gases represented by A, and B, to give
the compound AB, On
A(g) * B2(9) = 2AB(g)
At equilibrium, the concentration of
A, = 3.0 x 107? M, of B, = 4.2 x 107? M, of AB = 2.8 x 10? M
If the reaction takes place in a sealed vessel at 527°C, then the value of
K. will be NEET 2012
Ay) + Bag) = 2AB(y)
_ AB}?
Ko [42][B2]
(2.8103)? O
7 (30x10 *)(42x10 3) 3.0x4.2
= 0.62
A 20 litre container at 200 K contains CO (y) at pressure 0.4 atm
and an excess of SrO (neglect the volume of solid SrO). The
volume of the container is now decreased by moving the movable
piston fitted in the container. The maximum volume of the
container, when pressure of CO, attains its maximum value, will be
(Given that : SCO, = SrOf,) + CO, (o), K, = 1.6 atm) NEET 2017
A 20 litre container at 200 K contains CO (y) at pressure 0.4 atm
and an excess of SrO (neglect the volume of solid SrO). The
volume of the container is now decreased by moving the movable
piston fitted in the container. The maximum volume of the
container, when pressure of CO, attains its maximum value, will be
(Given that : STCO, = SrO() + CO.) K, = 1.6 atm) NEET 2017
A 20 litre container at 200 K contains CO, (,) at pressure 0.4 atm
and an excess of SrO (neglect the volume of solid SrO). The
volume of the container is now decreased by moving the movable
piston fitted in the container. The maximum volume of the
container, when pressure of CO, attains its maximum value, will be
NEET 2017
SrCO yo) = SrO(,) + CO.
A pco, X Psro
Pr Psrco,
2(9) À K, =1.6 atm
16 = Peo, (+ Psro = Psrco, = 1)
Let the maximum volume of the container when
pressure of CO, is 1.6 atm be VL
During the process, PV = constant
-.0,4 x20=1.6 x V
_ 0.4 x 20
>V =5L
1.6 a
In which of the following equilibrium K, and K are not equal?
In which of the following equilibrium K, and K are not equal?
NEET 2010
K_ and K, are related by the equation,
Pp e
K, = K (RT) %%g
When An, = difference in the no. of moles of products
and reactants in the gaseous state.
for 2C,.) + O,,_) = 2CO.
An, = vit ay? » #0 F9)
Factors affecting equilibrium constant
+ Kdepends on the stoichiometry of the reaction.
If two chemical reactions at equilibrium having equilibrium constants K,
and K, are added then the resulting equation has equilibrium constant
K=K, x K, on adding
Equation Equilibrium constant
CE mom
k= D»
rk,
(4) muh
ply with nm”
ne = nB
- 3t= 2% | el
E 2° >
( — B,k
k, = |
kl"
®
h=B %
CE PF } k,
E, OT
(Add) (sub)
A+c= BM A-c= RD
AZ BEC
et
2
Factors affecting equilibrium constant
If the reaction having equilibrium constant K, is reversed then resulting
equation has equilibrium constant 1/K,
A(g) + Big)= C(g)+D(g) |, ky
On reversing, C(g) + D(g) = Alg) + B(g) K = 1/k,
If a chemical reaction having equilibrium constant K, is multiplied by a
factor n then the resulting equation has equilibrium constant K = (K)", n
can be fraction
Equation Equilibrium constant
D,(g) = 2A(g) K,
(rai 1/2 D, (g) = A(g) KEK = JR
R=)”
If the equilibrium constant for N
= 2N0 q) i is K, the
2(g) + 26)
equilibrium constant for — 3 Vaio) + 3040 = = NO,\will be
NEET 2015
= | u N
K |
Y
'-()
O: '
\_
CE Belk
Vedantu
If the equilibrium constant for N,(,) + O,
'a(g) = 2NO „is K, the
1 1
equilibrium constant for 3 Mao) + 3 Oxo) = NO,,,will be
NEET 2015
If the equilibrium constant for N,¡¿, + O,(,) = 2NO;,) is K, the
2(9)
1 1
equilibrium constant for 320) + 3 Oxo) = NO,,,will be
NEET 2015
If the reaction is multiplied by 1/2, then new equilibrium
constant, K' = K'2,
Factors affecting equilibrium constant
e Equilibrium constant is dependent only on the temperature.
It means Ko and K, will remain constant at constant temperature no matter
how much changes are made in pressure, concentration, volume or
catalyst TO E,
However if temperature is changed,
ÚS
CS
BEE)
5% 7 2303R|T, 7%
I -IZRAZIS
If T, > T, then K, > K, provided AH = +ve (endothermic reaction)
not,
¡Van't hoff equation
—_
K, <K, if AH = -ve (exothermic reaction)
(x=) Exo Endo (1H =+:e)
ER | ED
— TT,
AT TY, 2:
Tr / Lor CET
\ \
For a given exothermic reaction, K and K’, are the equilibrium
constants at temperatures T, and T,, respectively. Assuming that
heat of reaction is constant in temperature range between T, and
T, ‚it is readily observed that 1 “TL 7 NEET 2014
For a given exothermic reaction, K and K’, are the equilibrium
constants at temperatures T, and T,, respectively. Assuming that
heat of reaction is constant in temperature range between T, and
T, , itis readily observed that NEET 2014
For a given exothermic reaction, K and K’, are the equilibrium
constants at temperatures T, and T,, respectively. Assuming that
heat of reaction is constant in temperature range between T, and
T, , itis readily observed that NEET 2014
Ky _ __AH [1 1
log = — 303% E ii
For exothemic reaction, AH = —ve i. e. ‚Heat is evolved.
The temperature T, is higher than T, .
1 1 \: A
Thus, ( _ 4)is negative.
So, log K', — log K, > log K’,
or Ky > K’,
Given that the equilibrium constant for the reaction,
280,(4) + 9,0) = 280.4) Ic
Has a value of 278 at gYarticular temperature. What is the value
of the equilibrium constant for the following reaction at the same
1
temperature? SO, = SOx.) + 320)
By adding equations (i), (ii) and (iii), we get
KK}
2NH, +20, = 2N0+3H,0, K=
1
1. Predicts the extent of a reaction on the basis of its magnitude
2. Predicts the direction of the reaction
3. Calculate equilibrium concentrations
Predict the extent of reaction
- _[Product] Ng
Ko, Reactant de
rw) | (Bagesad)
7
Case - | Case - Il Case - Ill
K >103 10% <K,, < 10° Ko < 107
eq Appreciable “
[Product] > [Reactant] concentrations of both [Product] < [Reactant]
In this case, the reactants and products In this case, the
reaction is are present reaction is
( product favourable’) Po > reactant favourable
Predict the extent of reaction
Negligible Extremely
(very low) large
Reaction 10° L 10° Reaction
hardly, Both reactants and press
proceeds products are — products are almost to
resent at
completion
equilibrium
—
Predict the direction of reaction
At each point in a reaction, we can write a ratio of concentration terms
having the expression same as the equilibrium constant expression.
This ratio is called the reaction quotient denoted by the symbol Q.
Reaction quotient (Q) helps in predicting the direction of a reaction.
The reaction quotient is a variable quantity with time.
— —
1
ke c 8-
&>te
Backwoxd
Q= Ke
Equilihnium.
Q< ke
Food Rin
Predict the direction of reaction
aA + bB = cC +dD
CD;
NT
Q > At any time during reaction
The concentration [C] , [D], [A], [B]
are not necessarily at equilibrium
The reaction, 2A() + Bog) = 3C (5) + Do) is begun with the
concentrations of A and B both at an initial value of 1.00 M. When
equilibrium is reached, the concentration of D is measured and
found to be 0.25 M. The value for the equilibrium constant for this
reaction is given by the expression NEET 2010
2A + Big) = 3c + D
Initial moles: 1 1 0° d”
Moles ateq.:1-(2 x 0.25) 1-0.25 3x0.25 0.25
=0.5 = 0.75 = 0.75 = 0.25
aja _ lero]
Equilibrium constant, K = aria]
_ (0.75)°(0.25)
(0.5)? (0.75)
The reaction quotient (Q) for the reaction
N,(9) + 3H,(9) = 2NH,(g)
Is given by q= INGE . The reaction will process from right
: TA]
to left if NEET 2003
O + |
lc JONA |
O ]
The reaction quotient (Q) for the reaction
N,(g) + 3H,(g) = 2NH,(g)
Is given by q= Her . The reaction will process from right
2
to left if NEET 2003
The reaction quotient (Q) for the reaction
N,(g) + 3H,(g) = 2NH,(g)
Is given by g= INGE . The reaction will process from right
INR]
to left if
NEET 2003
For reaction to proceed from right to left,
Q > e
(backward (forward
rate) rate) ¡.e. the reaction will be fast in backward
direction i.e r, > r,
Relation between Equilibrium constant & gibbs free
energy
e From thermodynamics
AG = AG? + RTInQ
AG = Gibbs energy change
R = Gas constant
T = temperature in Kelvin
= a i m
Q = Reaction quotient At 1 A =0
At equilibrium, when AG = 0 and Q = Ka then - AG + 0
AG° =-RTInK, _
AGO = - 2.303 RT log K, & - E
Relation between Equilibrium constant & gibbs free
energy
AG*= -RT InK,,
AG? = -2.303 RT log K,,
o Spontaneous Reaction in forward
AG°<0
reaction direction
at AG°>0 Non spontaneous | Reaction in backward
reaction direction
M", AG? = -2:303RTlog, Ke
Hydrolysis of sucrose is given by the following reaction:
Sucrose + H,0 = Glucose + Fructose. If the equilibrium constant
(K,) is 2 x 10% at 300 K, the value of A.G° at the same temperature
The equilibrium concentrations of the species in the reaction A + B
=C + Dare 2, 3, 10 and 6 mol L”, respectively at 300 K. AG? for the
reaction is (R = 2 cal/mol K)
NEET 2023
AG = -2.303Rt log K
Here, RB = 2cal do = 300K
On solving we will get,
AG = —1381.8 Cal
Le chatelier's Principle
e If a change is applied to the system at equilibrium, then equilibrium
will be shifted in that direction in which it can minimise the effect of
change applied and the equilibrium is established again under new
conditions.
Le chatelier's Principle
Ba erect of concentration |
BE erectortemperature |
_ EZ
Le chatelier's Principle
e Effect of concentration :
N, (9) + 3H,(9)+ 2NH, (9)
Concentration Direction of equilibrium shift
Addition of reactants Forward
Removal of reactants | Backward
Addition of Products | Backward
ye Removal of products | Forward
eYNote : The Édition of any solid component Hoes not affect the
equilibrium.
o.
R —
e?
RT, prund US
t (9) Go
ockwoMd. N
Al jr wooffect
PT
| Battu
Dy. Am Gry or Dec conc So!
pp od ham
Le chatelier’s Principle Dry = MM
Effect of pressure :
On increasing pressure, equilibrium will shift in the direction in which
pressure decreases (no. of moles in the reaction decreases) and vice
versa.
Moles (A n) Pressure Direction of shift
Increases
Backward direction
Decreases Forward direction
Increases
Forward direction
Decreases
Backward direction
Increases or
decreases
No shift
Pressure. > PT, mo: mes ave RSS
mary?
PL | moles ate more
Volume > VP ¡md moler mae,
dai Vi y No SP males leg
Le chatelier's Principle
e Effect of volume :
1
va P
Direction of
(A n,) Volume pressure equilibrium
An>0 "> Decreases Increase pe
An>0M Vie increases Decreases Forward direction
An<0Npe Ta Decreases Increase Forward direction
An<0 We h R Increases Decreases di cay
An=0 Np = Increases or Increases or No shift
decreases decreases
Le chatelier’s Principle
e Effect of inert gas addition :
Inert gas addition has no
effect at constant volume
Np?
An, > 0, reaction will shift in forward
direction :
An, < 0, reaction shift will in [ Np< "a:
backward direction
| b
An, =0, no effect : (mo Me it)
> cmt vo L= meet
ar a comite Preuve
(React 0 Mee MO q mola)
Le chatelier's Principle
e Effect of temperature :
To L
k
TU) EEK
logKz — logK, = -ve
T 1, K |, Equilibrium shift
in backward direction
He
logK; — logK, = +ve logKz — logK, = 0
k>k logK, = logk ah
T 1, K 7, Equilibrium shift in No effect)pf temperature on
rward direction, me Wad lecken,
‘onc. of product
conc. of reactant f
und > Pressu
opp x. the change’in = ? volume >
Fr, ng] males les PAL
"p= |, m=? | MR
Which one of the following conditions will favour maximum
formation of the product in the reaction
Ata) + Bag) = Xzray AH = X kd?
2(9) = 2NH, (4) + heat
The equilibrium shifts in forward direction
NEET 2014
As the forward reaction is exothermic and leads to
lowering of pressure (Produces lesser number of
gaseous moles) hence, according to Le Chatelier's
principle, at high pressure and low temperature, the
given reversible reaction will shift in forward direction
to form more product.
Vedantu
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Acids , base theories
Acids Dissociates in water to give hydrogen ions ( H* )
[std campo: A ER
HX (aq) x
Bases Dissociates in water to give hydroxyl ions (OH)
Example : Ca(OH),
+ S
NaOH (aq) — Na + OH
Acids are proton donors and bases are proton acceptor)
Acid: (Fe(H,O)¿P*, HCI , Base: NH,
NH, (aq) + H,O (I) = NH,' (aq) + OH (aq)
Base Acid
+ Modified. Arhenius concept =
HA+HD <= Hp +A
+ r
H +0 > HD
(=)
x dvonium
vo yo Y aes
ae Gov ugaie Ban x ñuda
HS E HU HS
(A) (Ce)
SA — w cb
WA>SCB
a) Hy80y & Sy (ar) X
b) H so, % #80, (Mt) Y
Rad 4 ik CB fas att
Only me ÿ
N + yw —> Nt,
(2) (cA)
>>
ait one H*
Acids , base theories
Acids accepts electron pair and bases donates
electron pair Acid : AICI,, BF, , Base: NH, PH,
BF, + :NH,— BF,:NH,