RxN's Unit 1 Flashcards
How can you meassure the rate of a reaction?
Mass change (in an open system where gas must be produced, mass changes as the gas escapes)
A distinct colour change
Temp change (Due to rxn producing heat)
Preassure change (Only measurable if gases are present. Since rxn is producing gas, NO2, the rxn can be carried out in a closed system)
What is Kinetic Molecular Theory (KMT)
A chemical reaction take splace due to a collision between the reactant molecules. Molecules MUST collide in order to react!!
What is the intermediate molecule?
A species formed when reactant molecules come together in the process of being formed. Consumed in the further reaction.
How does Temperature affect rxn rate?
Increased temp=increased rxn rate (molecules have more kinetic energy–>move faster–># of collisions per second increases meaning rate will increase
How does Surface area affect rxn rate?
Increased SA=increased rxn rate
Increasing SA increases number of sites availabe for collisions–> rate increases since # of collisions increases
How does concentration affect rxn rate?
Increased concentration=increased rxn rate
Increasing concentration increases # of molecules–>more molecules to collide with=higher chance of successful collisions increases
How does pressure affect rxn rate?
(only effective if a gas is present)
Increases pressure=increased rxn rate
Increasing pressure increases the concentration of molecules (they don’t decreases they become compressed)–> increasing pressure increases concen of molecules–> # of collisions increases
How does nature of reactants affect rxn rate?
Slow Due to:
Bonds being strong or unreactive
Electrons are tightly held together
Require many bonds to be broken or formed
Reactions involve molecules which require several stages.
The greater the tendency to lose or gain electrons, fewer bonds to break/form–> faster reaction
What is a catalyst, what does it do?
A substance which increases the rate of a reaction, involved in the reaction but regenerated at the end. Provides overall rxn with an alternative mechanism
Increases rate of rxn by lowering activation energy
What is an inhibitor?
Chemical which reduces the rate of a rxn by preventing further rxn from taking place
What is a Homogenous Rxn?
A reaction in which all reactants are in the same phase (state)
Ex. Two gases, two substances both dissolved in water, two miscible liquids)
What is a Heterogenous Rxn?
A reaction in which all reactants are in different phases
Ex. A solid and a liquid, a liquid and a gas, a gas and a solid. two immiscible liquids)
What is the trend in Rxn Rates?
Fast–> Aqueous ions (move fast/freely, ions have oposite charges attracting eachother)
Medium–> Gases and liquids (gases further apart, liquids particles close but don’t move fast)
Slow–> Solids (particles packed tight together)
Does changing concentrationn, pressure, etc. of a product change the rate of forward rxn?
No but it can affect reverse rxn
In what Rxn’s can surface area only be changed?
Heterogenous rxn’s where more than one phase reactant is present
