Consider the reaction 2 x2y + z2 ⇌ 2 x2yz which has a rate law of rate= k[x2y][z2] select a possible mechanism for the reaction. group of answer choices
step 1: z2 --> z + z (slow) step 2: x2y + z → x2yz (fast) step 3: x2y + z → x2yz (fast) step 1: x2y + z2→ x2yz2 (slow) step 2: x2yz2 → x2yz + z (fast) step 1: 2 x2y + z2 → 2x2yz (slow) step 1: x2y + z2 → x2yz + z (slow) step 2: x2y + z → x2yz (fast) step 1: 2 x2y ⇌ x4y2 (fast) step 2: x4y2 + z2 → 2 x2yz (slow)

Answer : The correct possible mechanisms for the reaction is:

Step 1 :     (slow)

Step 2 :     (fast)

Explanation :

Rate law : It is defined as the expression which expresses the rate of the reaction in terms of molar concentration of the reactants with each term raised to the power their stoichiometric coefficient of that reactant in the balanced chemical equation.

As we are given the overall reaction,

The given expression of rate law for this reaction is,

Now we have to determine the possible mechanisms for the reaction.

The rate law expression for overall reaction should be in terms of and .

As we know that the slow step is the rate determining step.

Option 1 :

Step 1 :     (slow)

Step 2 :     (fast)

Step 3 :     (fast)

The rate law expression will be:

Option 2 :

Step 1 :     (slow)

Step 2 :     (fast)

The expression of rate law for this reaction will be,

Option 3 :

Step 1 :     (slow)

The expression of rate law for this reaction will be,

Option 4 :

Step 1 :     (fast)

Step 2 :     (slow)

The rate law from the slow step 2 is,

      .............(1)

Now applying steady state approximation for , we get:

     .........(2)

Now put equation 2 in 1, we get:

The rate law expression will be:

Option 5 :

Step 1 :     (fast)

Step 2 :     (slow)

The rate law from the slow step 2 is,

      .............(1)

Now applying steady state approximation for , we get:

     .........(2)

Now put equation 2 in 1, we get:

The rate law expression will be:

From the given options we conclude that the only option 2 is the correct possible mechanisms for the given reaction.

Hence, the correct possible mechanisms for the reaction is:

Step 1 :     (slow)

Step 2 :     (fast)