symbol of Heat

[Baoying Li 1B]

What do these symbols represent specifically? H, delta H, Delta H naught, qp, q.

[Cole Woulbroun 1J]

H can be viewed as a system's enthalpy, or its total internal energy. While this energy often takes the form of heat, this is not always the case. It can apply to other forms of energy as well. Since H represents energy, delta H represents the change in this energy over the course of a chemical reaction. Delta H naught represents this change at standard conditions, as based on the conditions the reaction undergoes, the delta H value can change. Q represents solely heat energy, as it is directly related to the heat capacity of a substance, or the amount of heat energy that must be put into a substance to increase its temperature. As for Qp, I am not sure, but it is likely a derivative of Q, which represents heat energy.

[Connie Chen 1E]

I believe q_p is the heat energy at a constant pressure, and when there is a constant pressure, q_p=delta H.

[Ariel Davydov 1C]

As the above comment says, delta H represents the change of energy in a reaction from its final state to its initial state, regardless of the path it took to get there. q is the heat given off by a system during a reaction, and its sign will tell us whether the reaction is exothermic (negative value) or endothermic (positive value), similarly to delta H. qp will be the same as q and delta H (an expression of heat and/or energy) but in a reaction where pressure is held constant, as denoted by the “p.”