All Flashcards
Define 'elementary reaction'.
A single-step reaction involving one or a few molecules.
What is an 'endothermic reaction'?
A reaction that absorbs energy from the surroundings; reactants + energy → products.
What is an 'exothermic reaction'?
A reaction that releases energy into the surroundings; reactants → products + energy.
Define 'activation energy (Ea)'.
The minimum energy required to start a reaction; the energy difference between reactants and the transition state.
What is the 'activated complex'?
The highest energy, most unstable point in a reaction; bonds are partially broken and formed.
Define the 'Arrhenius equation'.
The equation, , that describes how the rate constant of a reaction changes with temperature.
Label the axes of a potential energy diagram.
X-axis: Reaction Progress/Coordinate, Y-axis: Potential Energy.
On a potential energy diagram, what does the peak represent?
The peak represents the activated complex or transition state.
On a potential energy diagram, how do you identify ΔH for an exothermic reaction?
ΔH is the negative energy difference between the reactants and products.
On a potential energy diagram, how do you identify ΔH for an endothermic reaction?
ΔH is the positive energy difference between the reactants and products.
On a potential energy diagram, what represents the activation energy?
The energy difference between the reactants and the transition state.
Differentiate between endothermic and exothermic reactions.
Endothermic: Absorbs energy, products have higher potential energy. Exothermic: Releases energy, products have lower potential energy.
Compare activation energy (Ea) and ΔH.
Ea: Energy to reach the transition state. ΔH: Overall energy change between reactants and products.
What's the difference between a first-order and second-order elementary reaction?
First-order: Rate depends on one reactant. Second-order: Rate depends on two reactants.