What happens to the rate constant (k) as the activation energy (Ea) increases, according to the Arrhenius equation?
As the activation energy (Ea) increases, the rate constant (k) decreases, meaning the reaction rate slows down. This is because a higher energy barrier makes it harder for reactants to convert to products.
Which of the following statements about the Arrhenius equation are true? Select all that apply: (A) It relates the rate constant to temperature and activation energy. (B) The frequency factor (A) represents the number of collisions. (C) The gas constant (R) is always 8.314 J/(mol·K) when discussing energy. (D) The equation can be rearranged into a linear form for plotting ln(k) versus 1/T.
All statements (A, B, C, and D) are true. The Arrhenius equation relates k to temperature and activation energy, A is the frequency factor, R is 8.314 J/(mol·K) for energy calculations, and the equation can be linearized for plotting ln(k) versus 1/T.
According to the linear form of the Arrhenius equation, what is the slope of a plot of ln(k) versus 1/T equal to?
The slope of a plot of ln(k) versus 1/T is equal to -Ea/R, where Ea is the activation energy and R is the gas constant.
What are two alternative names for the frequency factor (A) in the Arrhenius equation?
The frequency factor (A) is also called the pre-exponential factor or the Arrhenius factor.
When should you use the two-point form of the Arrhenius equation?
Use the two-point form when you have two rate constants and two temperatures for a reaction and want to compare how k changes with T.
What is the value and unit of the gas constant (R) used in the Arrhenius equation for energy calculations?
The gas constant (R) is 8.314 J/(mol·K) when discussing energy, speed, or velocity.
How does increasing the reaction temperature affect the rate constant (k) according to the Arrhenius equation?
Increasing the reaction temperature causes the rate constant (k) to increase, speeding up the reaction.
What variable is represented by the y-intercept in the linear form of the Arrhenius equation?
The y-intercept in the linear form is ln(A), where A is the frequency factor.
In a plot of ln(k) versus 1/T, what does the x-axis represent?
The x-axis represents the inverse of temperature, or 1/T.
Why might you see two different versions of the two-point Arrhenius equation, and do they yield different results?
You might see two versions due to the order of temperatures and the sign of Ea, but both forms yield the same answer mathematically.