Verified Solution • 2025–26 Session
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QNEET-2024-Ch-11: NEET 2024 Chemistry - Class 11 NEET-2024-Ch-11 Solution: In which of the following equilibria \(K_p\) and \(K_c\) are…
In which of the following equilibria and are NOT equal?
Multiple Choice Options
- A PCl 5 ( g ) _ _ PCl 3 ( g ) _ + Cl 2 ( g ) _
- B H 2 ( g ) _ + I 2 ( g ) _ _ 2 HI ( g ) _
- C CO ( g ) _ + H 2 _ O ( g ) _ _ CO 2 ( g ) _ + H 2 ( g ) _
- D 2 BrCl ( g ) _ _ Br 2 ( g ) _ + Cl 2 ( g ) _
Step-by-Step Verified Solution
To determine in which of the given equilibria K p and K c are not equal, it's important to understand the relationship between these two equilibrium constants. This relationship is expressed by the equation:
K p = K c ( R T ) _ n
where R is the gas constant, T is the temperature in Kelvin, and _ n is the change in the number of moles of gas (number of moles of gaseous products minus number of moles of gaseous reactants).
If _ n = 0 , then K p and K c are equal because ( R T ) 0 = 1 . However, if _ n � 0 , the constants will not be the same, and the degree to which they differ will depend on the temperature and the value of _ n .
Now, let's analyze each option:
Option A: PCl 5 ( g ) _ PCl 3 ( g ) + Cl 2 ( g )
Reactant side moles = 1, Product side moles = 2; _ n = 2 _ 1 = 1 .
Option B: H 2 ( g ) + I 2 ( g ) _ 2 HI ( g )
Reactant side moles = 2, Product side moles = 2; _ n = 2 _ 2 = 0 .
Option C: CO ( g ) + H 2 O ( g ) _ CO 2 ( g ) + H 2 ( g )
Reactant side moles = 2, Product side moles = 2; _ n = 2 _ 2 = 0 .
Option D: 2 BrCl ( g ) _ Br 2 ( g ) + Cl 2 ( g )
Reactant side moles = 2, Product side moles = 2; _ n = 2 _ 2 = 0 .
From this analysis, it is evident that K p and K c are not equal in Option A where _ n = 1 . In all other options, since _ n = 0 , K p is equal to K c . Thus, the correct answer is Option A.