Chap 6: Rxn Rates Flashcards
(18 cards)
How is reaction rate measurd?
- volume: gas syringe
- mass: balance (Scale)
- temp: thermometer
- conductivity: electrical conductivity probe
- pressure: pressure sensor
- colour: spectrophotometer
- pH: pH meter
What are the 6 factors that affect reaction rate
- nature of the reactants
- concentration
- temperature
- pressure
- surface area
- catalysts
How does the nature of the reactants affect reaction rate
different molecules will react in different ways
how does concentration affect reaction rate
as concentration increases, the total number of collisions also increases
how does temperature affect reaction rate
as we increase temperature, we increase the number of collisions that will have sufficient activation energy
how does pressure affect reaction rate
increase pressure = increased collisions which lead to a faster rate
how does surface area affect reaction rate
an increase in surface area leads to an increase in collisions and a faster rate
how do catalysts affect reaction rate
they lower the activation energy and therefore increase the amount of effective collisions
what are the two things effective collisions must possess
- effective collisions must have the correct orientation
- effective collisions must have sufficient activation energy
what happens when you double or triple the concentration of something which is first order (m=1)?
- if you double the conc, you double the rate
- if you triple the conc, you triple the rate
what happens when you double or triple the concentration of something which is second order (m=2)?
- if you double the conc, you quadruple the rate (2^2 = 4)
- if you triple the conc, you get 9 times the rate (3^2 = 9)
what happens when you double or triple the concentration of something which is zeroeth order (m=0)?
- if you double the conc, the rate does not change (2^0 = 1)
- if you triple the conc, the rate does not change (3^0=1)
- if a reactant is raised to the zeroeth order, it is removed from the rate law equation
What is the overall order of reaction
equal to the sum of all the individual orders of reaction (add all the exponents; m + n + p)
whats an intermediate
chemicals produced in an earlier step and consumed in a “later” step
whats a catalyst
chemicals consumed in an earlier step and “reproduced” in a later step
whats the rate determining step
the slowest step among all the elementary steps in a specific multi-step reaction (this determines the rate of the overall chemical rxn)
** HAS SLOW WRITTEN NEXT TO IT
which step will have the largest activation energy
the rate determining step
how would you increase the rate knowing the mechanism
you would need to find a catalyst that lowers the Ea of the RDS and therefore incrases the rate of the overall rxn
