Shown below is a diagram depicting the enthalpy change of a
- a Is the reaction exothermic or endothermic?
- b What is the sign of ΔH?
- c What is the sign of q?
- d If the reaction does no work, what is the sign of ΔE for this process?
(a)
Interpretation:
The nature of the given reaction has to be identified.
Concept introduction:
Exothermic reaction:
If heat is released during a chemical or physical change those reactions are called as exothermic reactions.
Endothermic reaction:
If heat is absorbed during a chemical or physical change those reactions are called as endothermic reactions.
Answer to Problem 6.32QP
Given reaction is endothermic reaction because the enthalpy increases moving from reactants to products.
Explanation of Solution
Given information,
Figure 1
From the diagram we understand that the enthalpy of the reaction increases from reactants to products. Hence the given reaction is endothermic reaction.
(b)
Interpretation:
The sign of the enthalpy change
Concept introduction:
Exothermic reaction:
If heat is released during a chemical or physical change those reactions are called as exothermic reactions.
Endothermic reaction:
If heat is absorbed during a chemical or physical change those reactions are called as endothermic reactions.
Answer to Problem 6.32QP
The sign of enthalpy change
Explanation of Solution
Given information,
Figure 1
The enthalpy is increased from reactants to products so the sign of enthalpy is positive.
(c)
Interpretation:
The sign of heat
Concept introduction:
Exothermic reaction:
If heat is released during a chemical or physical change those reactions are called as exothermic reactions.
Endothermic reaction:
If heat is absorbed during a chemical or physical change those reactions are called as endothermic reactions.
Answer to Problem 6.32QP
The sign of
Explanation of Solution
Given information,
Figure 1
During the reaction the heat is absorbed so the sign of
(d)
Interpretation:
The sign of internal energy
Concept introduction:
Relationship between
The relationship between
Answer to Problem 6.32QP
The sign of internal energy change
Explanation of Solution
Given information,
Figure 1
Given information,
The reaction does no work.
The relationship between
Here, there is no pressure and volume work occurs, so the sign of internal energy change is positive
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