Multiple Choice Question about Enthelpy of Formation

AI Thread Summary
The discussion centers on the standard enthalpy of formation for different forms of chlorine: Cl2(g), Cl(g), and Cl-(aq). It clarifies that the standard enthalpy of formation for elements in their standard state is zero, which applies to Cl2(g) as the standard state of chlorine. The confusion arises from the interpretation of standard states, with Cl2(g) being the only form with a zero standard enthalpy of formation. The correct answer is identified as d) Cl2(g), emphasizing the importance of understanding standard states in thermodynamics. This highlights the need for clarity on definitions in chemistry to avoid misconceptions.
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Homework Statement



The term chlorine is used to mean a number of possible types of matter containing chlorine atoms, such as Cl2(g), Cl(g), and Cl-(aq). Which of these forms of chlorine would have a zero standard enthalpy of formation?

a) Cl2(g), Cl(g), and Cl-(aq)

b) Cl(g)

c) Cl-(aq)

d) Cl2(g)

e) Cl2(g), Cl(g)

Homework Equations



Enthalpy of Formation for Elements = 0KJ

The Attempt at a Solution



Really not sure where to begin, but the answer in the back of the book is d), and I can't understand why it's like that. Shouldn't it be a), since the enthalpy of formation for elements is always 0KJ
 
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Can you quote the definition of a standard state as was given to you?
 
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