The following mechanism has been proposed for the gas phase reaction of nitrogen monoxide with bromine.
step 1 fast: NO Br2 NOBr2
step 2 slow: NOBr2 NO 2 NOBr
(1) What is the equation for the overall reaction
(2) Enter the formula of any species that acts as a reaction intermediate?
(3) Complete the rate law for the overall reaction that is consistent with this mechanism.

1) The overall chemical equation will be :

2) The species which acting as a intermediate is .

3) The rate law for the overall reaction :

Explanation:

1)  Step 1 : Fast:

..[1]

Step 2: Slow:

...[2]

The overall chemical equation will be :

[1] + [2]

2) Intermediate are those chemical species are which formed in between the process of chemical reaction , but do not appears in overall reaction. They act as a product and reactant in the process where chemical reaction taking place in more than one step.

The species which acting as a intermediate is .

3) Rate law for the overall reaction that is consistent with this mechanism:

When the reaction is taking place in more than one  step than the rate of the reaction is determined by the step in which reaction progress is slow.

So, for the given mechanism the rate of the overall chemical creation will be determined by step 2:

Step 2: Slow:

...[2]

Rate of the reaction :

..[3]

From step 1 :

Putting value of rate expression [3]:

Where :

The rate law for the overall reaction :

the ideal gas law equation is as follows

pv = nrt

where p - pressure

v - volume

n - number of moles

r - universal gas constant

t - temperature

so if the pressure, volume and temperature are already known

we are left with n and r

since r is the universal gas constant that has a known fixed value then r too is known

so we are left with 'n'

once we know temperature volume and pressure

we can find the number of moles of gas present using the ideal gas law equation

this is not my own answer, this is an answer for the same question by the user blahblahmali. i do not claim ownership of this account.

the answer is 303.15 or 303