Difference between q=mCAT and AH=-mCAT (1 Viewer)

[chocolatelatte]

OKAY SO WHAT'S THE DIFFERENCE GUYS.
I KEEP USING THE SECOND ONE (DELTAH=-mCDELTAT) because it's in the syllabus, BUT THE MINUS ALWAYS THROWS THINGS OFF.
i am beyond confused!!!


thanks!
(sorry for caps, was getting pretty aggravated..)

 

[QZP]

Q or q (I have never clarified the distinction between the two but my teacher accepts both) specifically refers to the heat that is transferred in a reaction.
Change in enthalpy ΔH - is the total change in energy in a reaction.

They have the same formula because HSC only deals with constant pressure. Just mind the different signs as change in enthalpy indicates exothermic/endothermic whereas I believe q is just a magnitude.

 

[someth1ng]

To me, they have been the same thing. Pretty much the difference is the sign.

ΔH<0 is exothermic, ΔH>0 is endothermic.
q<0 is endothermic, q>0 is exothermic.

For HSC, I recommend that you use ΔH because that's what's on the formula sheet and what you are expected to use, not q.

 

[D94]

Q or q (I have never clarified the distinction between the two but my teacher accepts both) specifically refers to the heat that is transferred in a reaction.

In thermodynamics (which should apply to HSC Chemistry), Q is in units of Joules (J), whereas q is in units of Joules per unit mass (J/kg). Similarly for enthalpy, entropy and work.