I'm a little bit confused as im trying to work out the enthalpy change for the reaction between methane and chlorine free radical - CH4 + CL. ---> CH3CL + H.
I worked it out to be 74 kjmol-1 but this cant be right Help!
Surely we need to know the mass of water and heat change of the reaction as enthaply chnage is, q= m x c x delta T
We dont need to do anything that complicated thank goodnesss! :P I just did it by working out the bond enthaply of the reactants and products then added them together to find out the energy change ? I just assumed it had to be a negetive answer..
I'm a little bit confused as im trying to work out the enthalpy change for the reaction between methane and chlorine free radical - CH4 + CL. ---> CH3CL + H.
I worked it out to be 74 kjmol-1 but this cant be right Help!
Isn't the original equation supposed to be CH4 + Cl. --> CH3. + HCL?
Anyway if you're using bond enthalpy to work it out then add up all the bonds on the left hand side 4(C-H) and take away all the bonds on the right side (3(C-H) + (H-Cl)) then you should have your answer
We dont need to do anything that complicated thank goodnesss! :P I just did it by working out the bond enthaply of the reactants and products then added them together to find out the energy change ? I just assumed it had to be a negetive answer..
. I have never worked out enthalpy change like that though . It would be a negative answer if energy is given out e.g combustion or burning meanwhile heat will be taken in and would therefore be positive for an endothermic reaction e.g photosynthesis.
Isn't the original equation supposed to be CH4 + Cl. --> CH3. + HCL?
Anyway if you're using bond enthalpy to work it out then add up all the bonds on the left hand side 4(C-H) and take away all the bonds on the right side (3(C-H) + (H-Cl)) then you should have your answer
Thats exactly what I'm doing but im ending up with a postive enthalpy change for an exothermic reaction :s Anyway for this reastion - N2H4 + 02 ----> N2 + 2H20 I got the enthalpy change to be 38 kjmol-1??? Whats the correct answer, i cant see where im going wrong
Thats exactly what I'm doing but im ending up with a postive enthalpy change for an exothermic reaction :s Anyway for this reastion - N2H4 + 02 ----> N2 + 2H20 I got the enthalpy change to be 38 kjmol-1??? Whats the correct answer, i cant see where im going wrong
Unfortunately I haven't had the time to memorise all the average bond enthalpies so don't know the correct answer, if you're doing it the way I said then it's right