are exothermic reactions slower than endothermic reactions?

Question

How do you know which reaction is slow by looking at heat of reaction or activation energy?

Answer 1

Exothermic and endothermic indicate if the reaction produces or requires energy to take place. It has to do with whether the products have lower or higher energy (respectively) than the reactants.

The rate of the reaction depends on several factors (like nonscientific mentions). In terms of energy, the rate or reaction and the activation energy are associated via the Arrhenius equation k=A*e^(-Ea/RT).

So in fact the rate of the reaction will depend on the height of the activation energy (that peak you see in the potential energy diagrams for reactions). It doesn't matter where the level of the products is, only the height of the peak.

A very nice example is the reaction of H2 and O2. As we all know it is extremely exothermic but if you just mix 2 volumes of H2 and 1 of O2 practically nothing will happen. The activation energy is so high that the reaction occurs at an extremely low level and too slow pace for you to see it happening. If you light a match you provide enough energy for several molecules to overcome the high activation energy. Because the reaction releases large amounts of heat this helps more molecules overcome the energy barrier and thus you have a violent (in a way autocatalytic) reaction, leading to an explosion.

Answer 2

Well actually the rate of a reaction (how slow or fast a reaction is) depends on those factors:
1. Surface area of contact of the solid reactant with the other reactant.
2. Concentration of a solution reactant.
3. Pressure of the gaseous reactants.
4. Catalyst.
5. Temperature of the environment.

As you see, temperature does affect rate of a chemical reaction. However it is important to make a difference between the exo and endo types of reactions and the temperature that will, at some point, affect rate of reaction. The temperature that will affect rate of reaction is that of the environment the reaction is taking place in.

In brief, whether a reaction is exo or endo has nothing to do with the rate of a reaction.

Let's now take the case of an exothermic reaction. It is a chemical reaction where there's a net release of thermal energy (heat). If the reaction is performed under a flame, to increase the environment's temperature, then the reaction will be relatively faster.

For the case of an endothermic reaction, if the reaction is performed under the same flame, the reaction will carry on faster too. Heat will be absorbed and the products will be formed faster.

Answer 3

Exothermic reaction will undergo spontaneously as it does not require any energy, while endothermic reaction has to be supplied with energy to happen.Therefore, exothermic reaction will be faster than endothermic reaction.

Answer 4

exothermic reactions are faster than endothermic reactions generally we can proof this bu answering which faster an exploding bomb and making food of course bomb is faster.
if we look at the heat of reaction and activation energy exothermic reactions release much heat to the surrounding rather than the heat they take so they are called exothermic.exothermic reactions means combining bonds in the term of bonds .the activation energy needed to start exothermic reaction is not much according to its heat of reaction.endothrmic reactions are viceversa to them.

Answer 5

Exothermic reactions can be quite fast -- consider an explosion. There are many other factors at work controlling reaction speed other than enthalpy or activation energy; consider concentration of reactants and presence of catalysts, for example.

Answer 6

exothermic reactions are generally faster than endothermic ones since they are spontaneous. a large activation energy means that a rxn is slow and a small activation energy means that a rxn is fast.

Answer 7

Exo Reactions

Answer 8

Ice freezing isn't a chemical reaction; it extremely is fullyyt a transformation of state (there is not any substitute in chemical composition). nicely endothermic reactions look "chilly" because of the fact the gadget takes in capability from our environment. because of the fact our environment loses that capability, it feels chilly. in the time of exothermic reactions, the gadget releases capability to our environment, making it look warm. (this could be the combustion of gasoline case in point)

Answer 9

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