1. What specifically are you looking for in the IR spectrum to determine if the reaction has given the desired product? 2. What specifically are you looking for in the NMR spectrum to determine if the reaction has given the desired product?

You are looking for expected peaks in absorption spectra founded on structure of desired product, respectively on bound in desired compound. Every bond absorb specific energy from radiation which wavelength match to IR spectrum of light. Result of energy absorption is vibration of bond and bonded atoms (if they are not too heavy).That absorbed energy is seen as a peak in absorption spectra. These peaks are specific for each bound so you need to find peaks that mach to bounds in your desired compound and in that matter you can identify your compound.

In nuclear magnetic resonance you are looking for  peaks specific for atoms in your desired compound (H or C atoms). When external magnetic field is applied, atom goes in higher energy state. When atoms goes "relaxing", it releasing energy that mach energy gap from relaxed end excited state. That energy is detected on nuclear magnetic resonance spectra and it depends on neighbor atom so you can determine the position of atoms and identify structure of desired compound.

For better results it is the best to combine these two methods.

Explanation:

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