Chapter 5: 5.1 Reaction Rates and Rate Laws Flashcards
What governs the speed at which a reaction takes place?
- Reactants and their concentrations
- Temperature
- Catalyst present or not
For reaction:
aA + bB → cC + dD
What is the relationship between the rates for the various reactants and products?
Rate = -1/a(Δ[A]/Δt) = -1/b(Δ[B]/Δt) = 1/c(Δ[C]/Δt) = 1/d(Δ[D]/Δt)
State the equation for:
The rate of the reaction (rate law)
Rate = k[A]^x[B]^y
Where:
* k is the specific rate constant for the reaction at a given temperature
* x and y are the orders for each reactant
True or False:
The orders for reactants can only be found experimentally
True
In reaction order:
For [A]^x, if x = 0…
Zero order with respect to A
* Means that the reaction rate is independent of [A]
In reaction order:
For [A]^x, if x = 1…
The reaction is first order with respect to A
In reaction order:
For [A]^x, if the x = 2…
The reaction is second order with respect to A
In reaction order:
In [B]^y, if y = 0…
The reaction is zero order with respect to B
How do we determine the overall order of the reaction with formula:
Rate = k[A]^x[B]^y?
The overall order of the reaction is x + y
True or False:
Exponent values can only be whole numbers
False, they are usually whole numbers, occasionally 1/2 or -1/2
What does the initial slope mean on the plot of the gas pressure as a functino of time?
Initial reaction rate
What is a characteristic of a first order reaction?
A plot of ln[A], as a function of time should yield a straight line with a slope equal to -k
State:
The function for first-order reactions
ln[A]t = -kt + ln[A]0
Define:
Half-life
The amount of time it takes to use up half of the reactant
What is the trend of a half-life of a first-order reaction?
Exponential decay
