Chapter 8 #59  [ENDORSED]

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Michael Lonsway 3O
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Chapter 8 #59

Postby Michael Lonsway 3O » Sat Jan 14, 2017 4:10 pm

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?

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Re: Chapter 8 #59  [ENDORSED]

Postby mikezargari » Sat Jan 14, 2017 4:16 pm

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

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Re: Chapter 8 #59

Postby Timothy_Yu_Dis3A » Sat Jan 14, 2017 4:35 pm

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)).

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Re: Chapter 8 #59

Postby Kira_Maszewski_1B » Thu Jan 19, 2017 8:11 pm

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

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