Reaction rates 3.4 Flashcards
(30 cards)
What is rate of reaction?
Measures how fast a reactant is being used up or how fast a product is being formed?
What is the equation for rate of reaction?
Change in conc./ time
What are the units for rate of reaction?
moldm-3 s-1
What is the collision theory?
The theory that all particles must collide with sufficient energy and in the correct orientation
What affects rate of reaction?
- temperature
- conc.
- catalyst
- pressure
- surface area
How does temperature affect rates of reaction?
- increases
- more frequent collisions
- more kinetic energy
- more particles meet activation energy
How does concentration affect rates of reaction?
- increases
- more reacting particles
- increased chance/ frequencey of collisions
How does pressure affect rates of reaction?
- increases
- same number of particles in a smaller volume
- increased chance/ frequencey of collisions
How does surface area affect rates of reaction?
- increases
- more particles exposed to react
- increased chance/ frequencey of collisions
How do you measure rates of reaction?
- colour change
- change in mass
- volume of gas given off
What does a catalys do?
- icreases rate of reaction without being used up
- doesnt undergo permanent change
- lowers activation energy
- provides alternative route
What is a heterogeneous catalyst?
Different phase to the reactants
What is a homogeneous catalyst?
Same phase as the reactants
What are the advantages of a catalyst?
- lowers energy demands
- less fossil fules used
- less CO2 produced
- less environmental impact
- lower production costs
What does the area under the maxwell-Boltzman distribution graph show?
Number of particles in the system
What is the peak on the graph?
Most probable energy
Where is the mean on the graph?
Slightly right of the peak
What is equilibrium?
A reversible reaction where the rate of the forwards and backwards reactions are equal and the conc. of the products and reactants remain constant
What are le chatelieres principles?
If a dynamic equilibrium has its conditions changed the position of equilibrium will shift to counteract the change
What are the optimum conditions?
- best conditions for max yield
- profit margin
- environmental impact
- safety
What is the formula for Kc?
[products]/ [reactants]
What is the value of Kc affected by?
Change in temperature
What is the value of Kc not affected by?
- change in pressure
- adding a catalyst
- change in conc. of products/ reactants
What does a Kc of 1 mean?
Equilibrium is halfway between products and reactants
