Question

Can someone help please?
http://oi67.tinypic.com/6jf339.jpg

Answer 1

@CShrix
@LeibyStrauss
@whpalmer4

Answer 2

Use Hess's law

Answer 3

How so?

Answer 4

read this http://www.chemguide.co.uk/physical/energetics/bondenthalpies.html

Answer 5

Are you able to explain @hlilly2413 ?

Answer 6

Perhaps. Ok, so you're going to use bond energies to find the total heat change or change in enthalpy of the reaction. To do that you're going to take the sum of the bonds broken minus the sum of the bonds formed.

Answer 7

Alright but how do you know which are broken and such?

Answer 8

That's fine. I have no idea how to do it.

Answer 9

Don't stress. It's going to be easy. Do you know how to write out the compounds like how they're held together? (For example, O2 is two oxygen atoms held together by a double bond represented as O=O?)

Answer 10

Yeah.

Answer 11

I can do Lewis structures and such.

Answer 12

Ok, good. So you're going to do that for each of your reactants and products. Then, you're going to use your chart that shows the enthalpy for each. So, for oxygen gas you see that you have O=O and that is equal to 498 kJ/mol you would do 1(498kJ/mol) when you set up your equation.

Answer 13

I took a picture of the notes that I have from that section, so I'm going to send it to you in hopes that it helps. My professor didn't really review this and it wasn't on the test. :/

Answer 14

Alright. Thank you

Answer 15

It's really tiny. Sorry.

Answer 16

Hm. Let's see if this works. Hopefully they are of some use. hah.

Answer 17

Thank you so much!

Answer 18

No problem. Also, this on Khan Academy might help too. Unfortunately it isn't a video, but something might help https://www.khanacademy.org/science/chemistry/thermodynamics-chemistry/enthalpy-chemistry-sal/a/bond-enthalpy-and-enthalpy-of-reaction Good luck!

Answer 19

Thanks!

Answer 20

np

Answer 21

[2(351)+2(498.7)]-[2(799+799)]

Answer 22

wait, ok so I didn't work the problem out, but why do you have 2(799 + 799) ?

Answer 23

I thought you would if you had O=C=O

Answer 24

It still comes out to the same number, but I was looking at it as like you have 2 of those bonds in one formation...but you have two formations so I was thinking it would look like 4(799) because there would be 4 O=C bonds total.

Answer 25

Oh. Yeah. That looks better anyhow

Answer 26

or C=O either way it's still like 3,something so no worries. Sorry! :)

Answer 27

Thanks