Unit 3 - Rate Laws Quiz

General form of the Rate law(without k)

+ / -(depending on if its a reactant or product)delta (A)/ delta T

Rate law for zero order

R = k

Rate law for first order

R = k[A]

rate law for second order

R = k[A]²

Rate law with multiple reactants

R = k[A]^m [B]^n

what is K?

the rate constant, which is specific to each reaction due to their specific conditions

if m=0, then…

the rate is independent of concentration

if m=1, then

the rate is directly proportional to the concentration

if m=2, then …

the rate is proportional to the square of the concentration of the reactant

What does a zero-order reaction graph look like?

time vs. [A] is linear

What does a first order reaction graph look like?

t vs. ln[A] is linear

What does a second order reaction graph look like?

t vs/ 1/[A] is linear

what does t(1/2) represent?

(half life) the time required for half of a given reactant to be consumed

First order graph equation

ln[A]t = -kt + ln[A]0

Zero order graph equation

[A]t = -kt + [A]0

Second order graph equation

1/[A]t = kt + 1/[A]0

half life equation for first order reaction

t(1/2) = 0.693/k

how do you calculate half life for non-1st order reactions?

Using the equation that corresponds to the graph of the reaction order, and solving for t by setting A in ln[A]t to the half of the amount of starting amount of reactant(0.5)

Chemical equations are …

a summary of a multi-step process, and do not include how reactants become products, the activated complex, or intermediates

Reaction mechanisms are …

an attempt to explain the observed rate law, by using a series of proposed elementary steps

elementary reactions

one step in an overall reaction

if you have both the correct amount of activation energy and proper orientation then…

you exceeded the activation energy

if you increase the temperature of a reaction what will happen to the distribution curve?

It will shift right(not move right, just the peak will move right and become lower), but the activation energy will stay the same

Rule for overall rate law

intermediates can’t be in it

How do you replace intermediates if they show up in the overall reaction equation?

use the equilibrium step to solve for a substitution for the intermediate step

What is the rate determining step?

teh slowest elementary step in an overall reaction