For the processes described below, state whether it is appropriate to use Delta
ID: 3163087 • Letter: F
Question
For the processes described below, state whether it is appropriate to use Delta H = Q. Briefly explain why in each case. middot Two gases mix in a container of fixed size and react chemically. Two gases mix in a container with a freely-moving piston and react chemically. A solid is added to a liquid in a beaker open to the atmosphere. Remember that the Q in the first law of thermodynamics is the heat transfer to the system of interest. In A and B. consider processes that may include physical or chemical changes of a system, perhaps the mixture of substances in a beaker. A. As a process takes place, the system of interest feels hot to the touch. Is this process exothermic or endothermic? In this process, is Q positive, negative, or zero? If the process takes place a constant pressure, is Delta H positive, negative, or zero? B. As a process takes place, the system of interest feels cool to the touch. Is this process exothermic or endothermic? In this process, is Q positive, negative, or zero? If the process takes place a constant pressure, is Delta H positive, negative, or zero?Explanation / Answer
1. H=Q for the condition two gases mix in a container of fixed size and react chemically. Beacuse, In a reaction where temperatures and pressure are fixed.where as for the remaining two conditions, the pressure varies.
3.A) It is a Exothermic process.(Hot to touch)
Exothermic refers to a transformation in which a system releases energy (heat) to the surroundings, expressed by
Q < 0. ( Q is nagative)
When the transformation occurs at constant pressure, one has for the enthalpy H < 0, (H is nagative)
B. It is a endothermic process( cold to touch)
A system of reactants that absorbs heat from the surroundings in an endothermic reaction has a positive H,
Q >0(is positive)