The activation energy for the diffusion of carbon in chromium is 111,000 J/mol. Calculate the diffusion coefficient at 1100 K (827C), given that D at 1400 K (1127C) is 6.25 1011 m2/s

Explanation:

As the formula is as follows.

          D =

where,   D = diffusion coefficient

            = constant

            T = temperature

            R = gas constant

          = activation energy

For T = 1400 K,

For T = 1100 K,

Now,

      = exp (2.6)

                                 = 13.46

                   =

Thus, we can conclude that the diffusion coefficient at 1100 K is .

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