Topic 6: Chemical Kinetics Flashcards
Rate of Reaction
- the change i concentration of reactants or products per unit time
- SI Unit: mol/dm^3 s^1
What methods can be used to measure the rate of reaction?
- change in volume
- change in mass
- change in transmission of light
- change in concentration
- change in conductivity
- non-continuous methods
Methods to Measure the Rate of Reaction
Change in Volume
Methods to Measure the Rate of Reaction
Change in Mass
Methods to Measure the Rate of Reaction
Change in Transmission of Light
Methods to Measure the Rate of Reaction
Change in Concentration
Methods to Measure the Rate of Reaction
Change in Conductivity
Methods to Measure the Rate of Reaction
Non-continuous Methods
What are the 3 ways that rate of reaction can be expressed in?
- average rate
- instantaneous rate
- initial rate
Average Rate
Definition & Formula
- a measure of the change in concentration of reactant or product in a given time interval, t.
- average rate = △c/△t
△c =change in concentration of reactant or product
△t = time interval
Instantaneous Rate
Definition
- the rate at a particular time
- determined by finding the slope of the tangent to the concentration vs time curve at that time
Initial Rate
- is the instantaneous rate at the start of the reaction
- when t = t0, the instantaneous rate = initial rate
- initial rate = △y/△x
Rate Equation
- is a mathematical differential expression, which shows rate expressed in terms of concentration
- for example, in the reaction A + B → C + D, a rate equation can be writen as follows:
rate = - d[A]/dt = - d[B]/dt = + d[C]/dt = + d[D]/dt - if there is a coefficit in front of the terms, just turn the cofficiet into a fraction and multiply it with the values, for example: xA + yB → qC + pD, will have a rate reaction written like so:
rate = - 1/x ⋅ d[A]/dt = - 1/y ⋅ d[B]/dt = + 1/q ⋅ d[C]/dt = + 1/p ⋅ d[D]/dt
Kinetic - molecular theory of gas
- The particles in a gas are in constant, random motion
- The combined volume of the particles is negligible
- The particles exert no forces on one another
- Any collisions between the particles are completely elastic
- The average kinetic energy of the particles is proportional to the temperature in kelvins.
What conditions need to be fulfilled in
What conditions need to be fulfilled in
What conditions need to be fulfilled in
What conditions need to be fulfilled in
What conditions need to be fulfilled in
What conditions need to be fulfilled in
What conditions need to be fulfilled in
What conditions need to be fulfilled in
What conditions need to be fulfilled in
What conditions need to be fulfilled in
What conditions need to be fulfilled in
What conditions need to be fulfilled in
What conditions need to be fulfilled in
What conditions need to be fulfilled in
Collision Theory
What three conditions need to be fulfilled in order for a chemical reaction between two reacting particles to occur?
- The two particles must combine with each other.
- The colliding particles must have the correct mutual orientations.
- The reacting particles must have sufficient kinetic energy to initiate the reaction.
Activation Energy, EA
Definition
- the minimium energy that colliding particles need for a reaction to occur
Homogeneous Catalysts
- is in the same physical phase or state as the reactants
Catalysts
- is a substance that** increases the rate of a chemical reaction**, but is not consumed in the reaction itself
- provides an alternative pathway for the reaction and lowers the activation energy, Ea
Heterogeneous Catalysts
- is in a different phase or state from the reactants
