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!
(a) A high activation energy may slow down a spontaneous reaction to the point that it does not occur at a visible rate.
(b) A reaction is spontaneous because it leads to lower potential energy (deltaH is negative) and/or it increases entropy (deltaS is positive). DeltaH and deltaS are independent of the activation energy which catalysts can change.
DeltaG is defined in terms of deltaH and deltaS neither of which depends on the activation energy or on catalysts.
a. Well, when the temperature is low, the kinetic energy of the particles involved in the reaction is also low. This means they have less energy to collide with one another and overcome the activation energy barrier required for the reaction to occur. So, even though the reaction may be spontaneous (meaning it would occur naturally under proper conditions), it proceeds at an extremely slow rate or not at all, due to the lack of sufficient energy to get things going.
b. Ah, the marvelous catalyst! Adding a catalyst won't alter the value of delta "G" for the reaction. The delta "G" represents the change in free energy, which is related to the thermodynamics of the reaction. A catalyst works by providing an alternative pathway with a lower activation energy, allowing the reaction to occur more rapidly. So, it doesn't change the overall spontaneity or favorability of the reaction, just helps speed things up. Think of it as a little boost for the reactants, like a motivational speaker for particles.
a. The reason some reactions considered to be spontaneous at low temperatures may not proceed at a measurable rate or form any measurable quantity of products for several hours, days, or years is due to the presence of a high activation energy barrier. Even though the overall reaction is thermodynamically favorable (i.e., has a negative ΔG), the reactants may not possess sufficient energy at low temperatures to overcome the activation energy barrier and initiate the reaction. As a result, the reaction rate is extremely slow, causing a significant delay in the formation of products.
b. Adding a catalyst to the reaction will not alter the value of ΔG. A catalyst works by providing an alternative reaction pathway with a lower activation energy. It achieves this by temporarily binding to the reactant molecules and facilitating the formation of a transition state, which leads to the desired products. While a catalyst increases the rate at which a reaction occurs, it does not affect the thermodynamics of the reaction. Therefore, the value of ΔG remains unaffected by the addition of a catalyst.
a. The reason why reactions that are considered to be spontaneous at low temperatures may not proceed at a measurable rate or form any measurable quantity of products for several hours, days, or years is because although they have a negative Gibbs free energy change (ΔG), there is still an energy barrier called the activation energy (Ea) that needs to be overcome in order for the reaction to occur. At low temperatures, the particles involved in the reaction have lower kinetic energy and therefore move more slowly. This reduced kinetic energy makes it more difficult for the reactant particles to collide with sufficient energy and proper orientation to overcome the activation energy barrier and initiate the reaction.
b. The addition of a catalyst will not alter the value of ΔG for the reaction. ΔG represents the difference in Gibbs free energy between the reactants and the products, and it is a thermodynamic parameter that depends only on the initial and final states of the system. A catalyst increases the rate of the reaction by providing an alternative reaction pathway with a lower activation energy. It achieves this by forming temporary bonds with the reactant particles, stabilizing them and reducing the energy required for the reaction to take place. As a result, the catalyst speeds up the reaction, allowing it to reach the same equilibrium state more quickly, but it does not affect the overall energetics of the reaction. Therefore, the value of ΔG remains unchanged with the addition of a catalyst.