Question

The following reactions occur at 500K. arrange them in orderof increasing tendency to proceed to completion.

(least completion-->greatest completion)
1) 2NOCl <---> 2NO +Cl2 Kp=1.7 x 10-2
2) N2O4 <--->2NO2 Kp= 1.5x 103
3) 2SO3 <---> 2SO2 +O2 Kp= 1.3x 10-5
4) 2NO2 <---> 2NO +O2 Kp=5.9 x 10-5
A. 3<1<4<2
B. 3<4<1<2
C. 4<3<2<1
D. 4<3<1<2
show how you got it for lifesaver

Answer 1

B. 3<4<1<2

Step-by-step explanation:

Upon comparing all four equations, you would find that it is pretty much only the value of Kp that varies.

So we have to understand what Kp is and its relationship with tendency of completion.

Kp is the equilibrium constant calculated from the partial pressures of a reaction equation. It is used to express the relationship between product pressures and reactant pressures. It is a unitless number, although it relates the pressures.

So what is the significance?

If K is a large number, it means that the equilibrium concentration of the products is large. In this case, the reaction as written will proceed to the right (resulting in an increase in the concentration of products).

So what do we now?

We pretty much just have to arrange the equations in order of increasing K values.

Upon doing that, we are left with;

3) 2SO3 <---> 2SO2 +O2 Kp= 1.3x 10-5

4) 2NO2 <---> 2NO +O2 Kp=5.9 x 10-5

1) 2NOCl <---> 2NO +Cl2 Kp=1.7 x 10-2

2) N2O4 <--->2NO2 Kp= 1.5x 103

So the order is given as; 3<4<1<2