Five isomeric alkenes a-e each undergo catalytic hydrogenation to give 2-methylpentane. the ir spectra of these five alkenes have the following key absorptions (in cm-1): compound a: 912 (s), 994 (s), 1643 (s), 3077 (m) compound b: 833 (s), 1667 (w), 3050 (weak shoulder on c-h absorption) compound c: 714 (s), 1665 (w), 3010 (m) compound d: 885 (s), 1650 (m), 3086 (m) compound e: 967 (s), no absorption 1600-1700, 3040 (m) the alkene structures are given below. identify each compound.

what are the statements

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