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 the addition of a catalyst.
This statement is true. A catalyst primarily affects the activation energy of the reaction, lowering it to increase the rate of the reaction. Since the forward reaction is the only one mentioned, the activation energy of the forward reaction would be affected to a greater extent than the activation energy of the reverse reaction.
b. The value for the enthalpy of the reaction would be decreased by the addition of a catalyst.
This statement is false. A catalyst does not affect the enthalpy of the reaction. The enthalpy of the reaction remains constant and is -20.0 kJ/mol based on the given information.
c. The reaction is endothermic.
This statement is true. If the enthalpy of the reaction is negative (-20.0 kJ/mol in this case), it indicates that the reaction is endothermic. This means that the reaction requires the absorption of energy to proceed.
d. The reverse reaction is slower than the forward reaction (smaller rate constant).
Since there is no information given about the rate constants or the speed of the reaction, we cannot determine whether the reverse reaction is slower or has a smaller rate constant than the forward reaction. Therefore, this statement is inconclusive.
e. The reaction rate would be decreased by an increase in temperature.
This statement is false. Increasing the temperature generally increases the reaction rate for most reactions. A higher temperature provides the reactant particles with more energy, leading to more frequent and energetic collisions, which increases the reaction rate.
Therefore, the correct statement is:
c. The reaction is endothermic.
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 the addition of a catalyst.
When a catalyst is added, it provides an alternative reaction pathway with a lower activation energy. However, a catalyst affects both the forward and reverse reactions equally. Therefore, option a is incorrect.
b. The value for the enthalpy of reaction would be decreased by the addition of a catalyst.
A catalyst does not affect the enthalpy of reaction. It only provides an alternative pathway with lower activation energy. Hence, option b is incorrect.
c. The reaction is endothermic.
The enthalpy of reaction is -20.0 kJ/mol, which indicates that the reaction releases energy. In an endothermic reaction, the enthalpy change would be positive. Therefore, option c is incorrect.
d. The reverse reaction is slower than the forward reaction (smaller rate constant).
The activation energy for the forward reaction is 40.0 kJ/mol. A higher activation energy value generally corresponds to a slower reaction. However, without information about the activation energy of the reverse reaction, we cannot definitively conclude that the reverse reaction is slower. Therefore, option d is incorrect.
e. The reaction rate would be decreased by an increase in temperature.
According to the Arrhenius equation, an increase in temperature increases the reaction rate. Higher temperature increases the kinetic energy of molecules, allowing more collisions and more effective collisions, which leads to a faster reaction. Therefore, option e is correct.
In conclusion, the correct statement is: "The reaction rate would be decreased by an increase in temperature." (Option e)