## korosh23 one year ago Chemistry 12 Question! Can temperature change delta H or change in enthalpy? What about a catalyst?

1. Photon336

Catalyst only lowers the activation energy for the reaction both forward and reverse so it has no effect on say the delta H

2. Photon336

Delta G = Delta H - TDeltaS Raising temperature directly affects entropy because when you heat things molecules move around faster, ie more randomness. Enthalpy has to do with how much energy I'm guessing bonds broken - bonds formed if you consider bond dissociation energies. That quantity depends on how much energy is stored in that bond and how many Bonds you have, I'm not sure if temperature directly affects that. But also bond dissociation energies are intrinsic to that particular bond and probably depends on the strength of the bond too + how much energy is stored in that bond.

3. korosh23

@Photon336 this is the question! Which of the following changes coccur when the temperature of a reaction is increased? i. delta H of the reaction increases ii. More collisions iii. Increase in KE Answer is ii and iii. So, you mean temperature changes enthalpy, but why the answer did not include that?

4. Photon336

$\delta G = \delta H - TDelta S$

5. Photon336

@korosh23 so the answer is ii and iii the definition of temperature is average kinetic energy; $T = \frac{ 1 }{ 2 }mv ^{2} average$

6. Photon336

let's break this formula down, $v^{2} = average speed$ so lets look at this for one second. say we raised the temperature and made T bigger, and let's say we didn't add any more particles so the mass was constant. that means they would have to be moving faster their average speed would go up. ideally more collisions are implied from this as well because if the average speed of the particles is increasing then they must also be colliding more frequently; but i'm not an expert in that.

7. Photon336

the reason why I don't believe it increases the enthalpy delta H is because enthalpy has to do with how much energy you need to break a bond/ i.e. how much energy is released upon breaking the bond. those values don't depend directly on temperature. yes you need to raise the temperature to get the reaction going and to break the bonds but I don't think enthalpy would be affected see my explanation above @korosh23

8. korosh23