Hey guys! What is the rate constant is particularly sensitive to:
1 A change in volume
2 A change in pressure
3 A change in product concentration
4 A change in reactant concentration
5 A change in the activation energy
I feel like it is a change in the activation energy b/c the Arrenihus equation. I'm just unsure.
I agree with you from the choices given but I would choose temperature first if given that choice.
A 45.8 g sample of iron ore is treated as
follows. The iron in the sample is all converted
by a series of chemical reactions to Fe2O3.
The mass of Fe2O3 is measured to be 24.3 g.
What was the mass of iron in the sample of
ore?
Answer in units of g.
Good observation! The rate constant is indeed particularly sensitive to a change in the activation energy (option 5). Let me explain why.
The rate constant (k) is a key parameter in chemical kinetics that quantifies the rate at which a chemical reaction occurs. It is related to the rate of the reaction by the rate equation, which usually takes the form of:
rate = k[A]^m[B]^n
In this equation, [A] and [B] represent the concentrations of reactants, and m and n represent their respective reaction orders. The rate constant itself is dependent on several factors, including temperature, presence of catalysts, and the nature of the reactants.
Now, coming to activation energy (Ea), it is defined as the minimum amount of energy required for a reaction to occur. A higher activation energy means that more energy is needed for the reaction to proceed, and vice versa. When the activation energy is lower, more reactant molecules possess enough energy to overcome the energy barrier and form products. As a result, the rate of the reaction increases.
The Arrhenius equation, which you mentioned, allows us to quantify the effect of temperature on the rate constant:
k = A * e^(-Ea/RT)
In this equation, A is the pre-exponential factor (related to the frequency of successful collisions), e is the base of the natural logarithm, Ea is the activation energy, R is the ideal gas constant, and T is the temperature in Kelvin.
As you can see, the exponential term e^(-Ea/RT) directly involves the activation energy in the Arrhenius equation. This means that changes in the activation energy have a significant impact on the rate constant. Lowering the activation energy leads to a higher rate constant, thereby increasing the rate of the reaction.
While changes in volume (option 1), pressure (option 2), reactant concentration (option 4), and product concentration (option 3) can affect reaction rates, they do not have a direct impact on the rate constant itself. These factors influence the reaction rate by altering the number of collisions or the frequency of successful collisions, but the rate constant remains unchanged.
Therefore, option 5, a change in the activation energy, is the most sensitive factor affecting the rate constant.