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Flashcards in Reaction Rates Deck (17)
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1
Q

Reaction rates

A
  • measured in terms of the rate of disappearance of a reactant or appearance of a product
  • rates are expressed by moles per liter (mol/L) or molarity per second (M/s)
2
Q

Rate Laws

A

take form of
rate = k[A]^x[B]^y

x and y = the order of reaction
overall order of the reaction = x + y
must be determined from experimental data

3
Q

Rate order of a reaction is

A

the sum of all individual rate orders in the rate law

4
Q

Zero - order reactions

A
  • have constant rate that does not depend on the concentration of reactants
  • only factors affecting the are of zero - order reaction:
    temperature & addition of a catalyst
  • concentration VS time curve of a zero - order reaction rate is a straight line; the slope of such a line is equal to -k
  • Rate of formation of product C is independent of changes in concentrations of any of the reactants, A and B.

rate = k[A]^0[B]^0 = k
units: M/s

5
Q

First - order reactions

A
  • have a non-constant rate that depends on the concentration of reactant
  • concentration VS time curve of a first - order reaction rate is a non linear
  • directly proportional to one reactant, such that doubling the concenratio of that rectant results in a doubling of the rate of formation of the product
  • the slope of a ln[A] VS time plot is -k
  • graph shows that the rate of formation of product is dependent on the concentration of reactant

rate = k[A]^1 or rate = k[B]^1
units: M/s

6
Q

Second - order reactions

A
  • rate is proportional to either the concentrations of two reactants or to the square of the concentration of a single reactant.
  • have a non-constant rate that depends on the concentration of reactant
  • concentration VS time curve of a second - order reaction rate is a non linear
  • the slope of a 1/[A] VS time plot is k
  • graph curve shows that the rate of formation of product is dependent on the concentration of reactant

rate = k[A]^1[B]^1 or rate = k[A]^2 or rate = k[B]^2
units: M/s

7
Q

Broken order reactions

A

those with non-integer (fractions) orders

8
Q

Mixed order reactions

A

those that have a rate order that changes over time

9
Q

Zero order:

temperature is decreased so, the rate is

A

decreased

10
Q

First order:

temperature is decreased so, the rate is

A

decreased

11
Q

Second order:

temperature is decreased so, the rate is

A

decreased

12
Q

Zero order:

all reactants’ concentrations doubled so, the rate is

A

unaffected

13
Q

First order:

all reactants’ concentrations doubled so, the rate is

A

doubled

14
Q

Second order:

all reactants’ concentrations doubled so, the rate is

A

multiplied by 4

15
Q

Zero order:

catalyst is added so, the rate is

A

increased

16
Q

First order:

catalyst is added so, the rate is

A

increased

17
Q

Second order:

catalyst is added so, the rate is

A

increased