kinetics Flashcards
(19 cards)
What is collision theory?
Reactions occur when particles collide with sufficient energy (activation energy) and correct orientation.
What is activation energy (Ea)?
The minimum energy particles need to successfully collide and react.
What does increasing temperature do to reaction rate?
Increases kinetic energy → more particles exceed Ea → more successful collisions per second → rate increases.
What does increasing concentration or pressure do to rate?
More particles per unit volume → more frequent collisions → higher rate.
What does increasing surface area do to rate?
More exposed particles → more frequent collisions → higher rate.
What does the Maxwell–Boltzmann distribution curve show?
Distribution of particle energies in a sample at a specific temperature.
What are key features of the Maxwell–Boltzmann curve?
Starts at origin; peak = most probable energy; area under curve = total particles; only particles past Ea can react.
How does increasing temperature affect the Maxwell–Boltzmann curve?
Peak lowers and shifts right → more particles exceed Ea → area under curve beyond Ea increases.
How do catalysts increase rate?
They provide an alternative reaction pathway with lower activation energy.
Do catalysts affect the Maxwell–Boltzmann distribution?
No change in shape — but Ea line shifts left
What is a homogeneous catalyst?
A catalyst in the same physical state as the reactants — forms intermediate species.
What is a heterogeneous catalyst?
A catalyst in a different physical state from reactants — often solid with gas/liquid reactants.
What is the general rate of reaction equation?
Rate = change in concentration / time
What are the units of rate of reaction?
mol dm⁻³ s⁻¹
How is reaction order determined experimentally?
Using initial rate data and concentration–rate graphs or tables.
How can rate be measured in a gas-producing reaction?
Use a gas syringe or measure mass loss over time.
How can rate be measured for a color change?
Use a colorimeter to track absorbance over time.
