Question

Nitric oxide (NO) gas partially decomposes into nitrogen (N2) and oxygen (O2) gases after being placed in a closed container. 2NO (8) = N2 (8) + O2 (8) What is true about the reaction? O The rate of the forward reaction is at its maximum when pure NO gas is first placed in the container. O At equilibrium, the concentration of O2 gas is the same as the concentration of NO gas. O All of the NO gas is eventually converted into N2 and O2 gases. O The rates of the reactions do not change during the reaction.

Answer 1

1.)Rate of reaction is basically how quickly a reaction is proceding. Rate of reaction for 2NO (g) $\rightleftharpoons$ N2(g) + O2(g) is :

R = k[NO]2 , which decreases as reaction proceed. So option D is false.

ICE table:

	NO	N2	O2
I	a	0	0
C	-2x	+x	+x
E	a-2x	x	x

Clearly equlibrium concentration of O2 and NO are not same. So option B is false.

An equlibrium reaction never completes that means after a certain period of time amount of reactant and product becomes constant and does't change. So option C is false.

Rate of forward reaction = Kf[NO]2 , so if we put NO gas initially in the container rate of forward reaction will be maximum. So option A is true.

2. Pure solid and liquid are not included in equilibrium constant expression. This is because they do not effect the reactant amount at equlibrium in the reaction, so they are disregarded and kept at 1.

Given reaction :

3A(g) + 4B(g) $\rightleftharpoons$ 2C(s) +5D(l)

So equlibrium constant expression will be,

K = 1 /[A]3[B]4

3.) As explained in part 1, rate of forward reaction is maximum at the start of the reaction. So option A is false.

At equilibrium, rate of forward reaction becomes equal to rate of backward reaction and hence there is no change is in concentration of reactants or products that does not mean reaction has stopped or chemcial activity has stopped. It only means change in concentration is zero for each compund in the reaction. So option B is false.

A system in  equilibrium is affeccted due to

i) change in temperature of the system

ii) change in concentration of any reactant or product

iii) change in pressure of the system

iv) addition of some inert gas

v) addition of catalyst

Position of equilibrium of don't change over the time. So option C is false.

After equilibrium is attained both forward and backward reaction keeps on going , only concentration change of any reactant or product is zero. So option D is correct.

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