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Title: Why are so many exothermic reactions spontaneous? Explain how an endothermic reaction can be spontaneous? Post by: Fullcircle on Nov 2, 2013 Why are so many exothermic reactions spontaneous? Explain how an endothermic reaction can be spontaneous?
Title: Why are so many exothermic reactions spontaneous? Explain how an endothermic reaction can be spontaneous? Post by: tonyekwe on Nov 2, 2013 exothermic reactions are frequently spntaneous because as soon as 1 small part reaches the activation energy threshold it begins reacting. this releases enough energy to make the rest of the initial substance to start reacting.
if an endothermic reaction has a very low (basicaly no) activation energy, then it can procede without signifcant external energy applied. Title: Why are so many exothermic reactions spontaneous? Explain how an endothermic reaction can be spontaneous? Post by: Leeta c on Nov 2, 2013 All chemical and physical systems tend to achieve minimum energy and maximum entropy.
If the drive to achieve maximum entropy is greater than the drive to achieve minimum energy, an endothermic reaction may occur. Usually this results when solids react to form liquids or gases. Consider this reaction: Ba(OH)2(s) + NH4Cl(s) -----> BaCl2(aq) + NH3(g) + H2O(l) This is a reaction that I use in my classes to illustrate the principles described above. When these two dry solids are mixed at room temperature, the mixture gets wet, the odor of ammonia gas is detected, and it gets COLD. Since both a liquid and a gas are produced from the solids, the drive to achieve maximum entropy outweighs the drive to achieve minimum energy. Title: Why are so many exothermic reactions spontaneous? Explain how an endothermic reaction can be spontaneous? Post by: foodjunkie on Nov 2, 2013 for a reaction to be spontaneous a property of the reaction called "free energy" must be negative. and for an exothermic reactions the enthalpy is negative.
according to the equation delta G = delta H - T *delta S where G is the free energy and H is the enthalpy ... LHS must be negative this is favoured when H is negative so most of the exothermic reactions are spontaneous but for endothermic reactions H will become positive so it will depend on the other term so there are lesser endothermic spontaneous reactions |