## Chapter 8 #59 [ENDORSED]

Michael Lonsway 3O
Posts: 43
Joined: Wed Sep 21, 2016 2:57 pm

### Chapter 8 #59

Use the data provided in Appendix 2A to calculate the standard reaction enthalpy for the reaction of calcite with hydrochloric acid:

4HNO3(l) + 5N2H4(l) ----> 7N2(g) + 12H2O(l)

The solution manual subtracted the standard enthalpy of products from reactants, however, it didn't include the standard enthalpy for N2 which confused me. Can someone explain this problem?

mikezargari
Posts: 20
Joined: Wed Sep 21, 2016 2:56 pm
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### Re: Chapter 8 #59  [ENDORSED]

The enthalpy of N2 is 0 because N2 is nitrogen in its most stable form (nitrogen is found as N2 in nature).

Timothy_Yu_Dis3A
Posts: 11
Joined: Wed Sep 21, 2016 2:58 pm
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### Re: Chapter 8 #59

To elaborate, N2(g) -> N2(g) contains no broken or new bonds being formed. Therefore, the enthalpy is 0. The same can be seen in Oxygen gas (O2(g) -> O2(g)).

Kira_Maszewski_1B
Posts: 17
Joined: Wed Sep 21, 2016 2:57 pm

### Re: Chapter 8 #59

What is the equation that is being used to solve for the reaction enthalpy in this problem?

Return to “Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)”

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