Delta H and q Interchangeability

[Andy Liao 1B]

I was wondering if delta H and q are ever interchangeable. Are there certain circumstances that allow for them to be? Can someone please explain? Sometimes in the solutions manual, delta H is used instead of q, like for example, in problems 8.37 and 8.45.

[Swetha Sundaram 1E]

I think Delta H is only equal to q with a subscript "p" because the pressure has to remain constant for the equation to hold

[Erica Nagase 1H]

= q (heat) at a constant pressure

[Jingyi Li 2C]

delta H only equals to q at constant pressure.

[Clarisse Wikstrom 1H]

This is why sometimes Lavelle will write qp instead of q, indicating it is at constant pressure and is interchangeable with deltaH.

[Justin Chang 2K]

Yeah, the definition of enthalpy is the heat absorbed or released at a constant pressure. q with a subscript p means the heat absorbed or released at a constant pressure, so the two are interchangeable. If there is no subscript p after the q, however, then the two are not interchangeable.