Calorimeters [ENDORSED]

[shannon_tseng_3L]

What's the difference between a regular calorimeter and a bomb calorimeter? Which one do we use in thermochemistry?

[Myra Kurani 1L]

A regular calorimeter occurs at a constant pressure because it is an open system, so it occurs at the pressure of the atmosphere. In a bomb calorimeter, volume is constant and it is an isolated system.

[Diana_Visco_1l]

A coffee cup calorimeter occurs at constant pressure because it is exposed to the atmosphere, because it is partially unsealed. Therefore, volume is allowed to fluctuate. In contrast, a bomb calorimeter, occurs at constant volume and pressure is allowed to fluctuate because it is completely sealed from the atmosphere. It is great for equations involving gases.

[Sarai_Ferrer_3C]

In respect to the topic of calorimeters, homework problem 25 discusses a scenario that I can't seem to wrap my mind around. I understand the basic formula I need to apply, but could somebody explain to me why we use it as shown in the solutions manual and solve for the change in the internal energy of the neutralization reaction?