Unit 1-Test 1-Kinetics and Equilibrium Flashcards
What is the Kinetic Molecular Theory?
What is KMT supported by?
(Pg 469 in Text)
-It is a theory that states that matter is made of particles(atoms,ions,or molecules) in continuous or constant motion.
An increase in temperature:
- increases the speed of particles
-reduces the forces of attraction between particles (According to Text: A theory that explains the ideal gas behavior based on the basis of random motion of gas particles)
KMT is supported by…
Diffusion: particles of a gas spread to fill their container (“perfume in a room”)
Pressure: a balloon remains inflated because gas particles are continuously hitting the sides of the balloon
What is the Collision Theory? (Pg470)
- The theory that states reactant particles must collide with one another for a chemical reaction to occur.
- Particles must collide with proper orientation
- collisions must have enough intensity to break old bonds and allow new bonds to form.
Kinetic Energy
is the energy of motion, ex
Potential Energy
energy that is stored ex
Activation Energy(Ea)
the minimum energy that is required for a successful reaction between colliding molecules
Activated Complex
A highly unstable transition species that has partial bonds and is neither product nor reactant.
-It is a temporary,unstable, intermediate species that quickly decomposes to products.
Enthalpy/Delta H
Enthalpy change(Delta H)- is the difference between the potential energy (PE) of the reactants and the potential energy (PE) of the products.
Catalyst
A substance that increases the rate of a chemical reaction without being consumed by the reaction
Reaction Mechanism
a series of steps that make up an overall reaction
Enthalpy of reaction
the enthalpy change of a chemmical reaction. Delta H represents the heat of reaction or the enthalpy of reaction
Elementary process
?
Elementary reaction
- Each step in a reaction mechanism
- It is a reaction that involves a single molecular event ,such as a simple collision between atoms,molecules,or ions ;can involve the formation of different molecules,or ions;may involve a change in the energy of the starting molecules; cannot be broken down into simpler steps
Reaction intermediates
Molecules, atoms,or ions that are formed in an elementary reaction/step,and consumed in a later elementary reaction/ step, but are NOT included in the overall reaction.
Rate determining step
the slowest reaction step; determines the rate of the reaction.
Endothermic
absorb more energy than they release ( ex photosynthesis)
The Delta H of a endothermic reaction is always positive. On a PE diagram the products are higher than the reactants.
Endothermic Equation=
AB+C –> AC +B
Exothermic
-release more energy than they absorb(ex. burning)
The Delta H of an exothermic reaction is negative
-The reactants are higher than the products
Exothermic equation=
C+D + CD
PE diagrams
diagrams that show changes in potential energy( stored chemical energy) during a chemical reaction
Reaction Kinetics
is the study of the rate of a chemical reaction
What is reaction rate & its formula?
Reaction rate (Quantitative) measures how fast products are formed or how fast reactants are consumer. All reactions are bond breaking/bond forming events ,and the rate of a reaction depends on how quickly bonds are broken and how rapidly new bonds form. Note: KMT and the collision theory are used to explain reaction rate.
Change in Quantity Rate = ------------------------------
Change in time
Th units depend on what you’re measuring
What are 6 methods for measuring reaction rate?
- If there is an acid or base in the equation, monitor pH
- Record changes in gas volume if there is a gas
- If there is a gas in the equation, you can record changes in pressure
- If solids are present, record changes in mass
- Monitor absorption of light if there is colour change
- Changes in electrical conductivity indicate changes in ion concentration
With reference to the Collision theory, explain how concentration affects reaction rate
An increase in the concentration of a reactant usually increase the rate of a chemical reaction, this is because when the concentration increases..
- there are more particles
- which means more collisions between particles
- thus more successful collisions
With reference to the collisions theory, explain how temperature affects reaction rate
An increase in temperature increase the rate of a reaction
This is because a higher temperature results in
-more collisions between particles
-more intense collisions
-more successful collisions,faster reaction rate.
AN INCREASE IN TEMP BY 10C WILL USUALLY CAUSE THE REACTION RATE TO DOUBLE
explain how the nature of reactions affects the reaction rate
Compounds with fewer bonds to break will react more rapidly than compounds with many bonds
(ex. propane,C3H8, burns faster than candle wax , C25H52,because it has fewer bonds
- compounds with weak bonds react more rapid;y than compounds with strong bonds
- ions will react more rapidly than atoms and molecules
With reference to the collision theory, explain how surface area affects reaction rate
Crushing a solid to produce a powder,or changing a substance to the gas phase,EXPOSES MORE PARTICLES FOR COLLISION
if more particles are available for collision there will be:-more collisions-more successful collisions,and a faster rate.
With reference to the collision theory, explain how Catalysts affects reaction rate
a catalyst increases rate by providing a different reaction pathway or mechanism with a lower activation energy
- a catalyst IS NOT consumed by a chemical reaction
What is the heat of reaction?
It is the same had Delta H or enthalpy.In other words it
is the difference between the PE of the reactions, & the PE of products.
What is the formula for calculating Delta H, Ea rev,or Ea fwd
Ea fwd-Ea rev= delta H
