Ch. 16 Kinetics Flashcards
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59 Terms
Kinetics
The study of of rates of chemical reactions and reaction mechanisms
Rates of Chemical Reactions
how fast chemical reactions proceed to form products
Reaction Mechanisms
the steps involved in the change of reactants to products
Reaction Rates
the speed at which reactants are transformed to products
Reaction rates can be the increase…
in the molar concentration of a product per unit time
Reaction rates can be the decrease…
in the molar concentration of a reactant per unit time
Reaction Rate Formula for Products
+ △ [P] / △ t
Reaction Rate Formula for Reactants
- △ [R] / △ t
What factors affect reaction rates?
Concentration of reactants, presence of a catalyst, temperature, and surface area of the reactant
Rate is ____ proportional to reactant concentration
directly
As reactant concentration increases…
reaction rate increases
Catalyst
A substance that speeds up a chemical reaction without being consumed
How does a catalyst speed up a reaction?
By lowering the activation energy required
Rate is ___ proportional to temperature
directly
As temperature increases…
rate increases
As temperature decreases…
rate decreases
Rate is ___ proportional to the surface area of a reactant
directly
True or false: rate is dependent on surface area of a reactant
True
As surface area of reactant decreases…
rate decreases
True or false: reaction rates decrease as the reaction proceeds
True
Why do reaction rates decrease as the reaction proceeds?
Reactants are consumed during a chemical reaction, leading to a decrease in concentration, which decreases the rate of reaction
True or false: Reaction rates are ALWAYS positive
True
What happens to reactants in a chemical reaction?
They are consumed
Are reactants associated with a negative or positive symbol?
Negative (-)
What happens to products in a chemical reaction?
They are generated
Are products associated with positive or negative symbols?
Positive (+)
Rate of Formation of a Product Formula
+ △ [increase in concentration of products] / △ t
Rate of Formation of a Reactant Formula
- △ [decrease in concentration of reactants] / △t
How is rate determined?
by monitoring the change in concentration of a reactant other than product over time
What properties are easy to monitor when analyzing reactants and products?
Color, volume, and pressure
What properties are not easy to monitor when analyzing reactants and products?
Flammability and Mass
For volume, what must be constant?
Pressure and temperature
For pressure, what must be constant?
Volume and temperature
Why isn’t flammability an ideal property to monitor?
difficult to measure quantitatively
Why is mass not an ideal property to monitor?
Due to the Law of Conservation of Mass
Law of Conservation of Mass
Matter cannot be created or destroyed in a chemical reaction; it is conserved
What does the Rate Law reflect?
the relationship between reaction rate and concentration of reactants
Rate Law Formula
R = k [A]^n
Rate =
k[A]^n
What does “k” represent in the rate law?
the rate constant
What does [A] represent in the rate law?
the concentration of reactant A
What does n represent in the rate law?
reaction order
Define Reaction Order
the exponent (n) of the concentration of that spiced in the rate law
Rate order is determined…
experimentally
List the three kinds of reaction orders
Zero-Order, First-Order, Second-Order
n=0
Zero-Order
n=1
First-Order
n=2
Second-Order
True or false: Fractional/Negative Orders are impossible
False.
In the zero-order reaction…
rate is independent from reactant concentration
Zero-Order reaction formula
rate = k [A]^0 = k= M/s
In the First-Order reaction…
rate of reaction is directly proportional to the concentration of the reactant
First-Order formula
rate = k [A]^2
In the Second-Order reaction…
the rate of reaction is proportional to the square of the concentration of reactant
Second-Order formula
rate = k [A]^2
Negative-order formula
rate = k [A]^-1
What happens to the rate in a negative-order reaction?
Rate is multiplied by 1/2
What happens to the rate in a half-order reaction?
Rate is multiplied by square root
Half-Order reaction formula
rate = k [A]^(1/2)