Math Help

Fat_Smurf · Post by **Fat_Smurf** » Fri Oct 26, 2007 2:31 am

gawd I hate math

crazyskwrls · Post by **crazyskwrls** » Fri Oct 26, 2007 2:34 am

so in essence we are all right .....yey... ur problems are solved

i need help with my chem. i i dont know how to calculate teh enthalpy of combustion of ethlyene....

XemnasXD · Post by **XemnasXD** » Fri Oct 26, 2007 2:35 am

crazyskwrls wrote:so in essence we are all right .....yey... ur problems are solved

i need help with my chem. i i dont know how to calculate teh enthalpy of combustion of ethlyene....

i need numbers and then i can help you if you really want it

crazyskwrls · Post by **crazyskwrls** » Fri Oct 26, 2007 2:38 am

c2H4 + 3O2 -> 2CO2+ 2H2O

C2H4 52.3kj/mol

h2O -285.8 kj/mol

CO2 -393.5kj/mol

pressure: atm
temp 25C

i am so lost right now...

Shadowman20818 · Post by **Shadowman20818** » Fri Oct 26, 2007 3:13 am

Errr, long time since I've done change in heat content, can you give a general formula?

XemnasXD · Post by **XemnasXD** » Fri Oct 26, 2007 3:20 am

crazyskwrls wrote:c2H4 + 3O2 -> 2CO2+ 2H2O

C2H4 52.3kj/mol

h2O -285.8 kj/mol

CO2 -393.5kj/mol

pressure: atm
temp 25C

i am so lost right now...

i dunno what the enthalpy of O2 is but if you figure that out its the the total enthalpy of the products - the total enthalpy of the reactants. srry it to long i was eating dinner....that should help you though

crazyskwrls · Post by **crazyskwrls** » Fri Oct 26, 2007 10:01 pm

thats all they give me, i dont know whats the general formula been looking through my books cant find it,

they didnt give u enthalpy for O2 cuz it is always 0

oh well i handed it in anyways made up a random number

Shadowman20818 · Post by **Shadowman20818** » Fri Oct 26, 2007 10:08 pm

crazyskwrls wrote:thats all they give me, i dont know whats the general formula been looking through my books cant find it,

they didnt give u enthalpy for O2 cuz it is always 0

oh well i handed it in anyways made up a random number

It wasn't 7.5 was it -.-?

FireJammerXR · Post by **FireJammerXR** » Fri Oct 26, 2007 10:38 pm

the simplest form of the first expression is
1
---------------
x^7-4x^6+4x^5

XemnasXD · Post by **XemnasXD** » Sat Oct 27, 2007 3:50 am

Shadowman20818 wrote:
crazyskwrls wrote:thats all they give me, i dont know whats the general formula been looking through my books cant find it,

they didnt give u enthalpy for O2 cuz it is always 0

oh well i handed it in anyways made up a random number

It wasn't 7.5 was it -.-?

i got 1463.2 and since i think heat was created the answer is -1463.2

i think >>