chemistry?

Question

What is the value of Kc for the reaction?

2CO(g) + O2(g)---> 2CO2(g).  Kc =5.0x1018 at 25°C

CO2(g)---> CO(g) + 1/2 O2(g) Kc = ?? at 25 °C

1. 1.  Kc = 1/(5.0 x 1018)1/2

2. 2.  Kc = 1/(2.5 x 1018)

3. 3.  Kc = –(5.0 x 1018)/2

4. 4.  Kc = –(5.0 x 1018)1/2

5. 5.  Kc = 2/(5.0 x 1018)1/2 

 

Answer 1

 

Step 1:

First chemical  reaction is

2CO(g) + O₂(g)  <====> 2CO₂(g)                             Equation (1)

The reaction take place at temperature 25°C and equilibrium constant .

Second chemical  reaction is

CO₂(g)  <====> CO(g) + 1/2 O₂(g)                           Equation (2)

The reaction take place at temperature 25°C and equilibrium constant .

Find equilibrium constant for second reaction :

Reverse the first equation .

2CO₂(g)  <====>  2CO(g) + O₂(g)

If an equation is reversed Kc is inverted : K_c2 = 1/K_c1 .

Divide the coefficients of second equation by 2.

CO₂(g)  <====> CO(g) + 1/2 O₂(g)

If the coefficients are divided by 2, then take the square root of K_c.

Therefore the equilibrium constant for second reaction is

Substitute equilibrium constant of first reaction.

So the equilibrium constant is .

Option (1) is correct choice .

Solution:

 

Option (1) is correct choice .