Determine if chemical equation is exothermic or endothermic?

Thread starter TheRedDevil18
Start date Feb 23, 2013
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Chemical Endothermic Exothermic

In summary, an exothermic reaction releases energy in the form of heat while an endothermic reaction absorbs energy in the form of heat. The type of reaction can be determined by calculating the change in enthalpy, with negative ΔH indicating an exothermic reaction and positive ΔH indicating an endothermic reaction. The enthalpy change can be affected by factors such as the amount of reactants and products, temperature, pressure, and the presence of a catalyst. It is possible for a reaction to change from exothermic to endothermic or vice versa if the conditions are altered. The enthalpy change itself does not directly affect the rate of a reaction, but it can indirectly impact it by changing the energy of

Feb 23, 2013

TheRedDevil18

How would I determine, if given a chemical equation is exothermic or endothermic?
Eg. Mg + 2HCL[itex]\rightarrow[/itex]MgCl2 + H2

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Feb 23, 2013

Borek

Mentor

Experimentally, or browsing tables.

Feb 23, 2013

Ygggdrasil

Science Advisor

Insights Author

Gold Member

Look up the enthalpies of formation of the reactants and products then apply Hess's Law: https://en.wikipedia.org/wiki/Hess's_law

1. What is the difference between an exothermic and endothermic reaction?

An exothermic reaction releases energy in the form of heat, while an endothermic reaction absorbs energy in the form of heat.

2. How can I determine if a chemical equation is exothermic or endothermic?

You can determine the type of reaction by calculating the change in enthalpy (ΔH) of the system. If ΔH is negative, the reaction is exothermic. If ΔH is positive, the reaction is endothermic.

3. What factors can affect the enthalpy change of a reaction?

The amount of reactants and products, temperature, pressure, and the presence of a catalyst can all affect the enthalpy change of a reaction.

4. Can an exothermic reaction become endothermic, or vice versa?

Yes, it is possible for a reaction to change from exothermic to endothermic or vice versa. This can occur if the conditions of the reaction are altered, such as changing the temperature or pressure.

5. How does the enthalpy change affect the rate of a reaction?

The enthalpy change does not directly affect the rate of a reaction. However, it can indirectly impact the rate by altering the energy of the reactants and products, which can affect the activation energy required for the reaction to occur.