Sign of Energy Density

[Rebecca Remple 1C]

Hi all,

In homework problem 4D.9 we are asked to calculate the energy density of a reaction. I found the enthalpy, which was negative. This meant that energy/heat was being released. However, according to the solutions manual, the sign changed to positive when calculating the energy density of the reaction. I'm not sure why this is. Is energy density always positive, or was there a key word/phrase that was supposed to indicate a sign change. Please share your thoughts. Thank you!

-Rebecca Remple

[Alice Chang 2H]

I think energy density is always positive, since the definition of energy density is "the amount of energy stored in a given system or region of space per unit volume."

I don't think energy can be negative (but I may be wrong), so energy density can't be negative.

[Rebecca Remple 1C]

I think energy density is always positive, since the definition of energy density is "the amount of energy stored in a given system or region of space per unit volume."

I don't think energy can be negative (but I may be wrong), so energy density can't be negative.

Hi Alice,

Thank you so much for your help! I reviewed the concept and your explanation makes a lot of sense. Good luck on the midterm :)

-Rebecca