So far, I've been given the equation: N2 + 0.502 -----> N20
And I've been told the enthalpy change of formation for the following reactions:
C + N2O -----> CO + N2 = -193
C + O.5O2 -------> CO = -111
Now from that information I'm required to work out the enthalpy change of formation for N2O. any ideas how do do this? Am i meant to draw a Hess's cycle? I'm so stuck!!!
So far, I've been given the equation: N2 + 0.502 -----> N20
And I've been told the enthalpy change of formation for the following reactions:
C + N2O -----> CO + N2 = -193
C + O.5O2 -------> CO = -111
Now from that information I'm required to work out the enthalpy change of formation for N2O. any ideas how do do this? Am i meant to draw a Hess's cycle? I'm so stuck!!!
Thanks in advance guys!
Oh, and by the way the answer is +82
Yes you'll have to draw a Hess's cycle for that In your overall equation, N2O is the product, and N2O is present in one of those cycles...but it's a reactant rather than a product, so that reaction effectively goes in a the opposite direction, so you have to reverse the sign to +193.
If you've switched that around, one of the reactant molecules for that second stage then becomes CO, but as the second of those equations is already showing the formation of CO, you'd leave the sign that way around.
So -111 + (+193) = +82 which is the enthalpy change of formation...if that doesn't make sense I'll draw the Hess diagram
Yes you'll have to draw a Hess's cycle for that In your overall equation, N2O is the product, and N2O is present in one of those cycles...but it's a reactant rather than a product, so that reaction effectively goes in a the opposite direction, so you have to reverse the sign to +193.
If you've switched that around, one of the reactant molecules for that second stage then becomes CO, but as the second of those equations is already showing the formation of CO, you'd leave the sign that way around.
So -111 + (+193) = +82 which is the enthalpy change of formation...if that doesn't make sense I'll draw the Hess diagram
Yes please, I'm sorry could you draw one please Chemistry really isn't my strong point! I don't see how the second equation relates to the formation of N2O at all...
Yes please, I'm sorry could you draw one please Chemistry really isn't my strong point! I don't see how the second equation relates to the formation of N2O at all...
See if this makes any more sense? It's a tricky one to explain
See if this makes any more sense? It's a tricky one to explain
OK thanks I understand it a bit better now! But for 1 oh Hess's cycle I don't understand how the enthalpy is the same even when there's the extra nitrogen's in the equation
OK thanks I understand it a bit better now! But for 1 oh Hess's cycle I don't understand how the enthalpy is the same even when there's the extra nitrogen's in the equation
There's the right number of nitrogens, but you'll have to ignore the carbons, because technically the overall equation should be N2 + 1/2O2 ----> N2O + C
Not sure what you mean by overall equation - you are asked about the reaction of the nitrogen oxidation, and you have to express it using two given equations. If done correctly, there will be no carbon nor nitrogen left, you will be left just with the original equation.
There's the right number of nitrogens, but you'll have to ignore the carbons, because technically the overall equation should be N2 + 1/2O2 ----> N2O + C