Chapter 12: Kinetics

Rate:

change in some quantity versus time

What is kinematics?

the study of reaction rates

Rates of chemical reaction are usually __ to the concentration of the reactant?

proportional

How do you find the instantaneous rate?

it’ll be given by the slope of the tangent to the curve at a specified time

What is a tangent line?

one that touches a curve at a point without crossing over it

Initial rate =

tangent slope at t = 0

Ratio of slopes of tangent lines of different substances reflects the:

stoichiometric relationship

Rate depends on:

concentration

Rate law/Rate equation:

relationship between reactant concentration and reaction rate

What does rate order depend on?

particular system temperature, pressure, etc.

Overall reaction order =

sum of individual reaction orders

Rate laws are usually determined from:

experiments

What is the purpose of using an integrated rate law?

to calculate the concentration of a reactant or product at a specific time during a chemical reaction

What is Second Order Reactions – Pseudo First - Order Kinetics?

a chemical reaction that is inherently second-order, but is experimentally observed to behave like a first-order reaction because one of the reactants is present in a significantly large excess, causing its concentration to remain essentially constant throughout the reaction, effectively making the rate dependent only on the concentration of the other reactant

What factors affect reaction rates?

temperature, energy, concentration, surface area of reactants, catalysis

Increasing the temperature by 10 degrees C causes how much of an increase in rate?

x2 increase

Higher concentration =

molecules collide more frequently

The activation energy could also be called the:

activation barrier

Reaction Mechanism:

pathway proposed for the overall reaction and that accounts for the experimental rate law (an explanation of how reactants get to products)

Unimolecular reactions:

a chemical reaction where a single molecule rearranges its atoms to form one or more product molecules

Bimolecular reactions:

a chemical reaction where two reactant molecules collide and interact with each other to form products

Molecularity =

number of individual molecules or atoms participating in the elementary reaction

Reactions are limited by:

the slowest step (Rate determining step)

Catalyst:

a substance that increases the rate of a reaction without being consumed in the reaction (“consumed“ at in the first step and “produced“ again at the end)

Biological catalysts are:

enzymes

Homogeneous catalyst:

dissolved in solution or mixed with gas

Hydrogenation:

the process where hydrogen atoms bind to the double bond of a compound, facilitating its conversion to a single bond, in the presence of a catalyst

When calculating the order of reaction with respect to reactant A using a table, you need to:

pick the values where [reactant B] is constant/the same

Catalyst:

used in 1st step of a reaction and then produced again at the end

Intermediate:

produced in the 1st step of a reaction and is consumed in the 2nd step/end