Q Question

[Emily_Stenzler_2H]

Does q=CdeltaT whenever the reaction is closed while q=nCdeltaT when it is not closed? I am confused as to when we include n and when we don't based on the text book problems (for example, problem 4A13 doesn't consider n and I'm not sure why this is). How do we know which equation to use?

[Chem_Mod]

To determine this, look at what units are given to you and what units the final answer is requested in!

[Aditya Sundaram 3D]

C delta T is for calorimeters but when you find q for substances and reactions still use n/m (mol/grams) appropriately.

[Colin Juett 2F]

You need the moles if you are given the specific heat capacity, but you don't need them when given the heat capacity. If you're given a value with /mol, it is likely that you will need moles in the equation.

[Jordan Tatang 3L]

You can use either one depending on the information provided in the problem.

[Jenny Lee 2L]

C∆T can usually be used for calorimeters, whereas for substances we usually use q = nC∆T. Essentially, I think we use C∆T because a calorimeter is a single object receiving heat, and so we don't use n (moles) because in literal terms, it would mean that there are moles of calorimeters. By using C∆T, we just have the heat released/absorbed by the calorimeter.

[Jamie2002]

C∆T is generally used when calibrating calorimeters. q = nC∆T is used when substances are placed inside the calorimeter.

[Jacob Schwarz-Discussion 3I]

CdeltaT is normally used for calorimetry problems but when referring to substances we use c=nCdeltaT