Chemical Equilibrium(11th And 12th > Chemistry ) Questions and Answers
Explanation:-
Answer: Option D. -> Both forward and backward reactions occur at all times with same speed:
D
Chemical equilibrium is dynamic in nature because, reactants change into products and products change into reactants even after equilibrium is achieved. But rate of forward and backward reactions are same.
Explanation:-
Answer: Option D. -> A is false but R is true.:
D
Equilibrium is possible only in a closed vessel. Hence A is false.
Boiling occurs at a constant temperature at a given pressure. Hence R is true.
Explanation:-
Answer: Option C. -> 0.0199:
C
2 HI⇋ H2+l2
Initial no of moles−2 moles00at equilibrium2 moles−0.440.220.22
Kc=[H2][l2][HI]2=0.22×0.221.562=0.0199
An amount of solid NH4HS is placed in a flask already containing ammonia gas at a certain temperature and 0.50 atm pressure. Ammonium hydrogen sulphide decomposes to yield NH3 and H2S gases in the flask. When the decomposition reaction reaches equilibrium, the total pressure in the flask rises to 0.84 atm. The equilibrium constant for NH4HS decomposition at this temperature is
Explanation:-
Answer: Option D. -> 0.11:
D
NH4HS(s) ⇋ NH3(g) + H2S(g)
Initially,a0.5atm0at equilibrium..... .0.5+xx
Total Pressure at eqilibrium =0.5+x+x=0.84
⇒ x=0.17
Kp=PNH3(g)× PH2S(g)=(0.5+x)x=(0.5+0.17)×0.17=0.1139 atm2
Ammonia under a pressure of 15 atm at 27∘C is heated to
347∘C in a closed vessel in the presence of a catalyst. Under the conditions, NH3 is partially decomposed according to the equation,
2NH3 ⇋ N2 + 3H2 .The vessel is such that the volume remains effectively constant whereas pressure increases to
50 atm. Calculate the percentage of NH3 actually decomposed.
Explanation:-
Answer: Option B. -> 61.3%:
B
2NH3 ⇋ N2 + 3H2
Initial molea00
Mole at equilibrium (a−2x) x 3x
Initial pressure of NH3 of a mole = 15 atm 27∘C
The pressure of 'a' mole of NH3=p atm at 347∘C
∴15300=p620
∴ p=31 atm
At constant volume and at 347∘C,mole α pressure
∴a+2xa=5031
∴ x=1962
∴% of NH3 decomposed = 2xa×100
=2×19a62× a×100=61.33%
Explanation:-
Answer: Option C. -> Q< kc:
C
Reaction moves in forward direction if Q< Kc
Reaction moves in backward direction if Q> Kc
Reaction remains at equilibrium if Q=Kc
Explanation:-
Answer: Option B. -> 8.21 atm:
B
NH3(g) ⇋ 12 N2(g)+32 H2(g)Kc=K′c
K′c=(1100)12=0.1
Kp=K′c×(RT)△ n=0.1×(0.0821×1000)1=8.21 atm
Notes: Use R=0.0821 atm l mol−1K−1 as unit of concentration has been taken as mol/l while calculating Kc.
Explanation:-
Answer: Option B. -> High temperature will favor forward reaction.:
B
a) Increasing pressure favors the reaction in the direction in which no. of moles decreases. As number of moles is decreasing in forward direction, hence increasing pressure will favor the production of SO3
b) Increasing temperature favors endothermic reaction. Here forward reaction is exothermic; hence high temperature will not favor forward reaction.
c) k[SO3] Hence it will decrease on reducing conc. of SO3
d) Increasing the volume reduces the pressure. Hence it will favor backward reaction in this case as number of moles is increasing in backward direction.