Catalysts and angular dependence

[Parker Smith]

Since the catalyst (more specifically an enzyme) is holding the reactant(s) in the proper position for the reacting bonds to be weakened and accessed easier, then does a catalyst also increase the a angular dependence constant (A)?

[pmokh14B]

I think that would make sense but usually, the effect of the catalyst is represented in the Arrhenius equation as a lower Ea value.

[105335337]

While that does make sense, Dr. Lavelle said that it just lowers the value of Ea and the equation, so I am unsure.

[Jason Wu 1D]

I believe that's the case for most biological catalysts (enzymes) but not for some chemical ones. Catalysts usually modify the reaction mechanism, so while it will always make it easier for a reaction to happen, that does not necessarily mean it lowers angular dependence. It may just render the reactants into a type of intermediate that is easier to break apart, thus allowing more collisions to happen.

[Andrew Wang 1K]

For most chemical catalysts, the compound provides more thermodynamically efficient reactions. Different intermediaries, different (lower) activation energies.

[Hamna_Khan_2E]

Hi!

The angular dependence constant (A) is a term used in the Arrhenius equation, which explains the influence of temperature on the rates of chemical reactions. A catalyst has no direct impact on the value of A in the Arrhenius equation, as it does not alter the temperature dependence of the reaction rate.

However, a catalyst can raise the rate constant (k) in the Arrhenius equation by decreasing the activation energy (Ea). This is because the catalyst provides an alternate pathway for the reaction with a lower activation energy, making it easier for the reactants to cross the energy barrier and so enhancing the pace of the reaction.

Hope this helps!