## Lewis structures

Arrhenius Equation: $\ln k = - \frac{E_{a}}{RT} + \ln A$

Abigail Menchaca_1H
Posts: 104
Joined: Sat Sep 07, 2019 12:19 am

### Lewis structures

How can you tell if a reaction is endothermic or exothermic with just the lewis structures of the species?

PranaviKolla2B
Posts: 114
Joined: Fri Aug 30, 2019 12:17 am

### Re: Lewis structures

It is based on the bonds formed and the bonds that are broken. I believe it is (but can someone confirm): the more bonds that are formed - the more exothermic; the more bonds broken - the more endothermic (generally, not always).

Posts: 103
Joined: Sat Aug 24, 2019 12:15 am

### Re: Lewis structures

Based on Lewis structures, we know that it takes energy to break a bond, and energy is released to form bonds, so if bonds are being made then the reaction is endothermic, since it is taking in energy, and it bonds are being broken then it is exothermic, since energy is being released.

Diana A 2L
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### Re: Lewis structures

You would calculate the enthalpies of formation of the substances, and then subtract the enthalpy of the reactants from the enthalpy of the products to see if you get a positive or negative value. Negative, it'll be exothermic, positive endothermic.

Charysa Santos 4G
Posts: 107
Joined: Wed Sep 18, 2019 12:21 am

### Re: Lewis structures

If bonds are being broken, then that is endothermic (requires energy), but if bonds are being made then that is generally exothermic (releases energy).