8.51
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8.51
Chapter 8 problem 51: Why is the answer positive? and How do you get the enthalpy for carbon and water?
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Re: 8.51
The answer is positive because you can't have negative values for density. Like an object like TNT can't be -1 g/mL, just as you can't have negative grams of something.
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Re: 8.51
you can get the enthalipies for CO2 and H20 by looking at appendix 2A, they are given as -241.82 kJ/mol for water and -393.15 kJ/mol for CO2. These are the delta Hs for these specific compounds, but others are also listed in that section of the chem book. After getting these delta H values, you can multiply them by the number of moles of the specific compounds, then subtract reactions from products to find the total heat energy used in the reaction
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Re: 8.51
Technically, I think it can still be negative. The negative sign would just represent that x amount of KJ would be released per liter, so you could just clarify that if you choose to write a negative sign. However, my TA mentioned that in real-life applications, people typically just represent enthalpy density as a positive value.
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