some reactions that are considered to be spontaneous at low temperatures will not proceed at a measurable rate or form any measurable quantity of products for several hours, days, or years.
a. explain why this is.
b. will the addition of a catalyst alter the value of delta "G" for the reaction? explain.
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i'm not sure for an answer for A, but i think b will be a yes because a catalyst lowers activation energy and will take less time for a reaction to occur. help plz?
thanks!
Check the previous post at:
http://www.jiskha.com/display.cgi?id=1260062043
a. The question is bogus. What is the criteria some are "considering" spontaneous? Some list if deltaG is -, it is spontaneous. Maybe, and maybe not. Large - yes, but say -1.2 j/kg That is pretty close to zero. Reactions near zero, on the border of +-, are usually very slow, if they occur at all.
b. catalys lowers activation energy. your added statement does not have anything to do with deltaG
a. The reason why some reactions that are considered spontaneous at low temperatures do not proceed at a measurable rate or form any measurable quantity of products for several hours, days, or years is primarily due to the presence of a high activation energy barrier. Even though these reactions are thermodynamically favorable (have a negative value of delta G), they still require a certain amount of energy to surpass the activation energy barrier before the reaction can take place. At low temperatures, the kinetic energy of the molecules involved in the reaction is insufficient to provide the necessary energy for the reaction to occur at a significant rate.
b. The addition of a catalyst does not alter the value of delta "G" for the reaction. The role of a catalyst is to lower the activation energy required for the reaction to proceed, but it does not change the difference in free energy between reactants and products, which is represented by delta "G". By providing an alternative reaction pathway with a lower activation energy, a catalyst enables the reaction to occur at a faster rate at a given temperature, including low temperatures. However, the thermodynamic favorability of the reaction, as determined by delta "G", remains unchanged.