For a one step reaction, the activation energy for the forward reaction is 40.0 kJ/mol and the enthalpy of reaction is -20.0 kJ /mol. Which statement below is true?
a. The activation energy of the forward reaction would be affected to a greater extent than the activation energy of the reverse reaction by addition of a catalyst.
b. The value for the enthalpy of reaction would be decreased by addition of a catalyst.
c. The reaction is endothermic.
d. The reverse reaction is slower than the forward reaction (smaller rate constant).
e. The reaction rate would be decreased by an increase in temperature.
help
To determine which statement is true, let's analyze each option:
a. The activation energy of the forward reaction would be affected to a greater extent than the activation energy of the reverse reaction by addition of a catalyst.
In a one-step reaction, the catalyst affects both the forward and reverse reactions equally, reducing the activation energy for both. Each reaction has its own activation energy, but the addition of a catalyst reduces the energy barrier for both directions. Therefore, statement (a) is false.
b. The value for the enthalpy of reaction would be decreased by addition of a catalyst.
A catalyst does not affect the enthalpy of reaction. Enthalpy is a measure of the heat exchange during a reaction, and it remains unchanged with the addition of a catalyst. Therefore, statement (b) is false.
c. The reaction is endothermic.
The enthalpy of reaction is -20.0 kJ/mol, indicating an exothermic reaction. Given that the enthalpy of reaction is negative, heat is released during the reaction. Therefore, statement (c) is false.
d. The reverse reaction is slower than the forward reaction (smaller rate constant).
The activation energy for the forward reaction is given as 40.0 kJ/mol. A higher activation energy generally implies a slower reaction rate. However, the activation energy for the reverse reaction is not provided, so we cannot compare them. Therefore, we cannot determine if statement (d) is true or false.
e. The reaction rate would be decreased by an increase in temperature.
In a typical reaction, an increase in temperature generally leads to an increase in reaction rate. Higher temperatures provide more kinetic energy to the reactant molecules, enabling more frequent and energetic collisions that lead to successful reactions. Therefore, statement (e) is false.
Based on our analysis, the only statement that is possibly true is (d), but we cannot be certain without additional information on the reverse reaction's activation energy.