Odine atoms will combine to form I2 in liquid hexane solvent with a rate constant of 1.5×1010L/mol⋅s. The reaction is second order in I . Since the reaction occurs so quickly, the only way to study the reaction is to create iodine atoms almost instantaneously, usually by photochemical decomposition of I2. Suppose a flash of light creates an initial [I] concentration of 2.00×10−2 M . How long will it take for 94% of the newly created iodine atoms to recombine to form I2? Express your answer using two significant figures.

The time taken is  

Explanation:

From the question we are told that

    The  rate constant is  

    The initial concentration of iodine atom  is  

Generally the integrated  rate law for a second order reaction is  mathematically represented as

Where is the concentration of the remaining iodine atom  after the recombination which is mathematically evaluated as

      [100%  - 94%]

The reason for the 94%  is that we are told from the question that only 94% of the iodine atom recombined

=>  [6%]

=>  

substituting values

So

answer : third trial had the contaminated sample and the correct value for dhrxn should be 1000 kj/mol

explanation :

let us write down the given equations

equation 1 :

equation 2 :

equation 3 :

let us use hess's law to find out which 2 equations can be added to get the third equation.

let us reverse equation 2 and multiply it by 2. the new equation that we get is,

equation 4 :

let us add equation 1 & 4

the above equation is similar to equation 3 but has different value for dhrxn.

therefore third trial had the contaminated sample and the correct value for dhrxn should be 1000 kj/mol