A4 Kinetics I
No description yet. This curated deck is ready for daily study.
Card preview (24)
Explain the effect of increasing concentration in terms of frequency of collisions.
• higher concentration there are • more reactant particles in a given volume • more frequent collisions • more successful collisions per unit time • reaction rate increases
Explain the effect of increasing pressure of gases in terms of frequency of collisions.
pressure of a gas is increased, by decreasing the volume of a container molecules are pushed closer together the number of molecules remains the same but the space occupied is less more frequent collisions more successful collisions per unit time increase in the reaction rate
Define the term continuous monitoring.
recording the amount of a reactant or a product at regular time intervals during a single reaction
What is a catalyst?
catalysts speed up the rate of reactions without being used up by the overall reaction
What is the role of a catalyst?
allows a reaction to proceed via a different route with a lower activation energy increasing rate of recation
Explain the term homogenous catalyst.
catalyst and reactants are in the same phase
Explain the term heterogenous catalyst.
reactant and catalyst are in different phases
What is the economic importance and benefits of catalysts?
increased sustainability by lowering temperatures and reducing energy demand from combustion of fossil fuels with resulting reduction in CO2 emissions
Define rate of reaction
The change in concentration of a reactant or a product over time.
What does collision theory state what is needed for a chemical reaction to occur?
· particles must collide in the correct orientation · particles must collide with sufficient energy (the activation energy)
Methods of continuous monitoring: monitoring by gas collection
use a syringe to measure the volume of gas evolved
Methods of continuous monitoring: mass loss
set up the system on a balance so the decrease in mass of reactants can be measured
Methods of continuous monitoring: colorimetry
concentration change is monitored by measuring the amount of light absorbed by a sample
Methods of continuous monitoring: quenching
quenching a reaction at various times
Methods of continuous monitoring: physical
monitoring colour/pH/ion concentration over time
What do clock reactions and initial reactions allow you to determine?
allow determination of the rate of reaction for a specific concentration
What does the mean rate of reaction tell you?
the average rate for the reaction up to a certain amount of time
What is the equation for mean rate of reaction?
mean rate of reaction = quantity of product formed/time
Define the term specific rate.
Using a graph, the gradient of the curve at a specific time gives the actual rate of the reaction at that time.
How do you calculate the rate at a specific time?
drawing a tangent to the curve at that point, followed by calculating the gradient of the tangent drawn
What does the area under distribution curves equal?
number of particles
What does Ea stand for on the distribution curve?
minimum energy required for a successful collision/for a reaction to happen
Why does the distribution curve pass through (0,0)?
no particles have no size
What is the Maxwell - Boltzmann Distribution?
plot of the number of particles having each particular energy the energy is largely held as kinetic energy although particles can also vibrate and rotate