Romix Posted January 21, 2015 Share Posted January 21, 2015 Dissolution of NaOH in H2O Why this reaction is extorhermic? Link to comment Share on other sites More sharing options...
Aminoxyl Posted January 21, 2015 Share Posted January 21, 2015 It's because of the enthalpy of NaOH + H2O -> NaO- + H3O+ is negative. I can't remember the specific values for this but the principles lies behind the Gibbs free energy equation, you can learn a bit more about it here: https://www.chem.tamu.edu/class/majors/tutorialnotefiles/gibbs.htm But essentially the principles are when a system is in a higher set of energy to begin with (the reactants) and ends with a lower energy system afterwards (the products) you get an exothermic reaction. When you dissolute a compound in water it forms complexes with the water depending on how electronegative that compound is the reaction can be minor or large. Link to comment Share on other sites More sharing options...
studiot Posted January 21, 2015 Share Posted January 21, 2015 Dissolution of NaOH in H2O Why this reaction is extorhermic? Have you considered the entropy changes between the reactants and the products? Link to comment Share on other sites More sharing options...
hypervalent_iodine Posted January 22, 2015 Share Posted January 22, 2015 It's because of the enthalpy of NaOH + H2O -> NaO- + H3O+ is negative. I can't remember the specific values for this but the principles lies behind the Gibbs free energy equation, you can learn a bit more about it here: https://www.chem.tamu.edu/class/majors/tutorialnotefiles/gibbs.htm But essentially the principles are when a system is in a higher set of energy to begin with (the reactants) and ends with a lower energy system afterwards (the products) you get an exothermic reaction. When you dissolute a compound in water it forms complexes with the water depending on how electronegative that compound is the reaction can be minor or large. You might want to reconsider that equation. NaOH is absolutely, 100% not an acid. Link to comment Share on other sites More sharing options...
Aminoxyl Posted January 22, 2015 Share Posted January 22, 2015 (edited) You might want to reconsider that equation. NaOH is absolutely, 100% not an acid. Woops, yeah you're right, I didn't really think that one through, I was more concentrating on the principle but yes, NaOH doesn't donate H at all. Thanks for the correction! Sorry about that Edited January 22, 2015 by Aminoxyl Link to comment Share on other sites More sharing options...
studiot Posted January 22, 2015 Share Posted January 22, 2015 Aminoxyl I should check the stochiometry of your correction equation in post#5. Although you did not start the thread, you seem interested, did you understand my entropy comment? Link to comment Share on other sites More sharing options...
Aminoxyl Posted January 22, 2015 Share Posted January 22, 2015 (edited) I understood the entropy comment, as far as I am aware (and this is from basic pre-university chemistry that I was taught) entropy is the order state of a system. A system with a high amount of entropy for would be a disordely system with particles vibrating a lot. For example an ice-cube could be a system of low entropy and the water it melts into of higher entropy. Is that not correct?P.S. I got rid of it now to avoid any upset/confusion. I understood it wasn't balanced. Edited January 22, 2015 by Aminoxyl Link to comment Share on other sites More sharing options...
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