Describe a simple chemical test that could be used to distinguish between members of each of the following pairs of compounds (a) 4-Chlorophenol and 4-chloro-1-methylbenzene (c) 4-Methylphenol and 2,4,6-trinitrophenol (b) 4-Methylphenol and 4-methylbenzoic acid (d) Ethyl phenyl ether and 4-methylphenol

Explanation:

(A) Phenol gives violet color by complexation with Fe3+ solution . It is best identification...

(B) For b , same phenolic test can be done ...But other esterification is also possibility...

(C) Picric acid has a particular identification test ,  

(D) Here , like the first one , phenolic test with FeCl3 gives violet color for 4-ethylphenol and no color for ethyl phenyl ether...

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