Chapter 10 - Reaction Rates and Chemical Equilibrium

CHEM:1070 Final Exam

what is rate of reaction indicative of?

change in concentration of reactant or product / change in time

what is the collision theory?

states that chemical reactions occur through collisions between molecules or atoms

what are the three conditions must be satisfied for the chemical reaction to occur?

• collision

• orientation

• energy

how does collision support the collision theory?

the reactants must collide for the chemical reaction to occur

how does the orientation support the collision theory?

the reactants but align properly to break and form bonds

how does energy support the collision theory?

the reactants must provide sufficient energy of activation

what is activation energy?

the minimum amount of energy required to break the bonds between atoms of the reactants

what must happen with the activation energy for the reaction to occur?

the barrier must be overcome in order for reactants to be converted into products

what are factors that affect the rate of reaction?

• temperature

• reactant amount(concentration)

• presence of a catalyst

how does temperature affect rate of reaction?

as temperature increases the molecules move faster leading to higher possibilities of the molecules colliding

how does reactant amount(concentration) affect rate of reaction?

the higher the concentration the higher possibilities of there being collisions between molecules

how does presence of a catalyst affect rate of reaction ?

a catalyst provides a different pathway that has a lower activation energy, which provides more collisions has no other affect than that

what are reversible reactions?

reactions that occur in both the forward and reverse directions at the same time

what two rates do reversible reactions have?

a rate for the forward reaction and a rate for the reverse reaction

what happens to the forward reaction as time goes by?

it gradually decreases

what happens to the reverse reaction as time goes by?

it gradually increases

at equilibrium what is the formula?

rate of forward reaction = rate of reverse reaction

how can you identify if a rate of reaction is equilibrium on a graph?

the rates of the forward and reverse reactions meet at the same point

what happens to concentration of reactants as time goes by?

it gradually decreases

what happens to concentration of products as time goes by?

it gradually increases

how can you identify if a concentration is equilibrium on a graph?

when both points reach a point where both reactants and products are straight

what is the equation of the equilibrium constant?

Kc = [products] / [reactants]

when equilibrium is reach what does it mean when there is a small Kc?

there are mostly reactants and little reaction takes place

when is equilibrium is reached what does it mean when Kc ~ 1?

the products are around the same as the reactants

when equilibrium is reached what does it mean when there is a large Kc?

there are mainly products and reaction is essentially complete

what is reaction quotient?

Qc = [products] / [reactants] ← at particular time

reaction mixture is not at equilibrium if?

Qc not equal to Kc

reaction mixture is at equilibrium if?

Qc = Kc

what is la chatliers principle?

when a stress is placed on a reaction at equilibrium, the system responds by momentarily changing the rate of the forward or reverse reaction in the direction that relieves that stress until the equilibrium is reestablished

what happens to equilibrium when reactant is added?

the rate of forward reaction increases to form more products until equilibrium is reached again

what happens to equilibrium movement when reactant is added?

there is forward reaction toward the products

what happens to equilibrium when reactant is removed?

the rate of the reverse reaction increases to form more reactant until equilibrium is reached

what happens to equilibrium movement when reactant is removed?

there is reverse reaction, equilibrium is shifting towards the reactants

what happens to equilibrium when product is being added?

the rate of the reverse reaction increases to form more reactant to reach equilibrium

what happens to the movement of the equilibrium when product is added?

the reverse reaction is favored, and shifts towards the reactants

what happens to equilibrium when product is removed?

rate of forward reaction is increased toward the products to reach equilibrium

what happens to equilibrium movement when product is removed?

there is a forward reaction that shifts toward the products

what happens to concentration when volume is increased and decreased?

concentration is decreases and concentration is increases

what happens to concentration when pressure is increased and decreased?

concentration is increased and concentration is decreased

what relationship does concentration have with volume?

inversely proportional relationship

what relationship does concentration have with pressure?

directly proportional relationship

what is the equation for concentration?

n / V (mol/L) = P/RT

what happens if there are the same number of moles of reactants and products?

there will be no effect