Calorimeter equations

[keeganslomba3g]

What is the equation for q when using a calorimeter? Why is q = DeltaU sometimes?

[905942454-1K]

Qcal = CcalDeltaT, sometimes q = DeltaU when volume is constant. When volume is constant, no work is being done and w = 0. So DeltaU = q + 0.

[Sarah Egan 3A]

In a calorimeter, the equation for q depends on the conditions of the experiment.
When a reaction occurs at constant pressure use the equation qcal = (ccal) Delta T
When a reaction occurs at constant volume (such as a bomb calorimeter) use q = Delta U
The reason why q = Delta U sometimes, like in bomb calorimeter, is because no work is done on or by the system under those conditions where volume is constant.

[Averie Moore 2F]

When using a calorimeter, q = C * delta T, meaning that the head absorbed/released by the system is proportional to the temperature change and heat capacity of the calorimeter. Q is equal to delta U when the reaction occurs at a constant volume and no work is done on the system.