In chemical kinetics, the Arrhenius equation describes the temperature dependence of reaction rates: $k=A{e}^{-\frac{E_a}{RT}}$, where $k$ is the rate constant, $A$ is the frequency factor (or pre-exponential factor), $E_a$ is the activation energy, $R$ is the gas constant, and $T$ is the temperature.

The frequency factor $A$ is related to the frequency of collisions and the orientation of molecules. For bimolecular reactions, collision theory predicts a theoretical frequency factor, $A_{theory}$, based on the collision frequency. However, not all collisions lead to a reaction due to improper orientation. The steric factor, $P$, accounts for this and is defined as the ratio of the experimentally determined frequency factor ($A_{exp}$) to the theoretical frequency factor: $P=\frac{A_{exp}}{A_{theory}}$.

Given that the steric factor $P=4.5$, which is greater than 1, it means $A_{exp}>A_{theory}$. This indicates that the experimentally determined frequency factor is higher than the theoretical prediction from simple collision theory. The Arrhenius equation itself does not predict a specific value for $A$; it is an experimentally determined parameter. However, in the context of this question, "predicted by Arrhenius equation" likely refers to the theoretical collision frequency factor.

The activation energy $E_a$ is independent of the steric factor; $P$ only affects the frequency factor. A steric factor greater than 1 is unusual but possible for some reactions where the reaction probability is higher than expected from simple collision theory, possibly due to quantum effects or other factors. It does not imply that the reaction requires a catalyst; it can still proceed without one.

Analysis of Options:

Option 1: "The value of frequency factor predicted by Arrhenius equation is higher than that determined experimentally." – This is incorrect because $P>1$ means $A_{exp}>A_{theory}$.

Option 2: "Experimentally determined value of frequency factor is higher than that predicted by Arrhenius equation." – This is correct based on $P=4.5>1$.

Option 3: "The activation energy of the reaction is unaffected by the value of the steric factor." – This is correct; $E_a$ and $P$ are independent parameters.

Option 4: "Since P = 4.5, the reaction will not proceed unless an effective catalyst is used." – This is incorrect; a high $P$ does not prevent the reaction; it may even enhance it, and no catalyst is necessarily required.

Related Topics and Formulae:

Collision Theory: For bimolecular reactions, the theoretical rate is given by $Z{e}^{-\frac{E_a}{RT}}$, where $Z$ is the collision frequency. The steric factor is introduced to correct for orientation: $k=PZ{e}^{-\frac{E_a}{RT}}$, so $A=PZ$.

Arrhenius Equation: $k=A{e}^{-\frac{E_a}{RT}}$.