4. Traditional bomb calorimetry can be used to find the energy content of food. Why is it not always used?
O A. It's used all the time.
O B. It accounts for all the energy in the food even if some of it's largely excreted by the body.
O C. Most food won't fit in a bomb calorimeter.
D. It's too accurate, and people don't want to know how many calories they're actually
eating.

B. it accounts for all the energy in the good even if some of its largely excreted by th body

the reaction mixture contains some ammonia, plus a lot of unreacted nitrogen and hydrogen. the mixture is cooled and compressed, causing the ammonia gas to condense into a liquid. the liquefied ammonia is separated and removed. the unreacted nitrogen and hydrogen are then recycled back into the reactor .

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