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The qp symbol

Posted: Fri Jan 25, 2019 2:31 pm
by Harmony Becerra
When describing the qp symbol, the professor said the q is the heat given off and p means that is it under conditions with a constant pressure. Does q also refer to the head absorbed? Or is it just for heat given off? And if so, is there a symbol we should know about for heat absorbed?

Re: The qp symbol

Posted: Fri Jan 25, 2019 3:01 pm
by mcredi
If q is positive, we say that the reaction is endothermic, that is, heat flows into the reaction from the outside surroundings. If q is negative, then the reaction is exothermic, that is, heat is given off to the external surroundings.

Re: The qp symbol

Posted: Sat Jan 26, 2019 1:42 pm
by Nicole Elhosni 2I
q(p) is equal to the change in enthalpy, so the final enthalpy (H of products) - the initial enthalpy (H of reactants). So when heat is absorbed, the enthalpy of the the products will be higher than the enthalpy of the reactants, and then ΔH will be positive, and thus q(p) will be positive. When heat is released, the enthalpy of the products will be lower than the enthalpy of the reactants, and then ΔH will be negative, and thus q(p) will be negative.

Re: The qp symbol

Posted: Sat Jan 26, 2019 5:01 pm
by 904914909
The q refers to heat but qp is enthalpy because it describes heat under a constant pressure. Enthalpy can be endothermic or exothermic, meaning qp can be positive or negative as well