Lecture 1 Flashcards
study of chemical kinetics and the reactors in which they occur
chemical reaction engineering
study of the factors that influence the rate of reaction and the explanations for the rate of reaction
chemical kinetics
any chemical compound or element with a given identity
chemical species
the identity of a chemical specie is determined by
the kind, number, and configuration of that species’ atom
chemical reaction has taken place when
a detectable number of molecules of one or more species have lost their identity and assumed a new form by a change in the kind or number of atoms in the component, and/or by a change in structure or configuration
when chemical reactions occur, what is the law assumed
law of mass conservation (the total mass is neither created nor destroyed)
the rate of disappearance of a chemical species is
the number of molecules that lose their chemical identity per unit time per unit volume
3 basic ways of losing chemical identity
decomposition
combination
isomerization
type of reaction that involves one phase
homogeneous reaction
type of reaction that involves more than one phase and reaction occurs at or very near the interface between the phases
heterogeneous reaction
type of reaction that proceeds in one direction until the reactants are exhausted
irreversible reaction
type of reaction that can proceed in either direction, depending on the concentrations of reactants and products relative to corresponding equilibrium concentrations
reversible reactions
type of reaction that is one step
single reaction
type of reaction that is in series and parallel reactions
multiple reactions
refers to how fast or slow a reaction proceeds
reaction rate
reaction rate is measured as a
decrease in concentration of the reactants or an increase in concentration of the products
the rate at which a given chemical reaction proceeds can be expressed in several ways
- rate of disappearance of reactants and rate of formation of products
- rate law
rate law is also called
kinetic expression, rate expression, or reaction rate equation
where can you find rate laws?
national bureau of standards
what can be found in the national bureau of standards?
the activation energy, frequency factor, and reaction order
number of atoms or molecules interacting or colliding in a reaction step; it is based on stoichiometric equation
molecularity
is the ratio of stochiometric coefficients of species involved in the reaction
relative rates of reactions
reactions has an __________ if the reaction order of each species is identical with the stochiometric coefficient of that species for the reaction is written
elementary rate law
reactions where overall order cannot be defined or determined based on stoichiometric equations only but must be determined experimentally
non-elementary reactions
two types of reaction schemes
non-chain reactions
chain reactions
non-chain reaction
reactants -> intermediates
intermediates -> products
chain reaction
reactants -> intermediates
intermediates + reactants -> intermediates + products
intermediates -> products
they are series of elementary reactions involved in reactions that are added to form the overall reaction
reaction mechanisms
deducting mechanism from rate law/ approximation methods
- steady-state approximation
- rate-determining step/ rapid equilibrium method
effect of temperature on reaction rate
- based on the collision and transition state theory
- based on arrhenius law
explains why there are differences between the mechanisms and rates of reaction
collision theory
criteria for collisions to be considered effective
- there must be enough activation energy
- the particles must collide with proper orientation
provides a reaction pathway which has lower activation energy, thus hastens the reaction without changing the enthalpy of reaction
catalyst
It relates the rate of reaction of a species to its concentration at a particular point.
Rate Law
The Rate Law is determined by
by experimental observation
