Given the balanced equation representing a reaction:
2kclo3(s) ==> 2kcl(s) + 3o2(g)
the oxidation state of chlorine in this reaction changes from
(1) -1 to +1 (3) +1 to -1
(2) -1 to +5 (4) +5 to -1

2b2t

explanation:

2b2t

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

the answer is a! (2.9 x 10^-18 j) hope i could someone. : )