Chemical Kinetics Flashcards
study that deals with how fast the reaction will proceed to completion
chemical kinetics
what is the formula for rate of reaction?
Rate = Δconc/Δt
or
Rate = Δ[A]/Δt
Δ = change; [ ] = conc. (in M usually); t = unit time; A = substance A
in a rxn, what do u call something that is consumed?
reactant
in a rxn, what is something that is formed?
product
If 4A → 2B, what is the rate expression?
rate expression = rate of disappearance = rate of formation
Rate = -1/4 Δ[A]/Δt = 1/2 Δ[B]/Δt
Accdg to the collision theory of reaction, atoms/molecules/ions must ____ for reactions to occur
collide
collision theory nga eh haha!
↑ or ↓ rxn rate?
more collisions
↑ reaction rate
in the transition state theory, what do you call the high energy intermediate that reactants must reach before falling into products?
transition state
in the transition state theory, what do you call the energy that reactants must acquire to reach the transition state?
activation energy
T or F
the rate of rxn is dependent on the reactants’ nature
True
same nature = ↑ rxn rate
↑ or ↓ rxn rate?
reactants have fewer and weaker bonds
↑ rxn rate
T or F?
reactions between molecules are slower than that of ions
True
mas mabilis ions kasi no bond-breaking is needed; can form bonds alr
↑ or ↓ rxn rate?
compounds by ionic bonds
↑ rxn rate
↑ or ↓ rxn rate?
the concentration of reactants is increased
↑ rxn rate
because collisions are more likely
↑ or ↓ rxn rate?
in gases, the pressure in a container is higher than normal
↑ rxn rate
↑P↓V lower volume = more compressed = more collisions
↑ or ↓ rxn rate?
in solids, the surface area is increased
↑ rxn rate
↑ surface area = breaking a solid reactant into smaller particles
breaking a solid reactant into smaller particles increases the number of particles available for collision
↑ or ↓ rxn rate?
in solids, the surface area is increased
↑ rxn rate
↑ surface area = breaking a solid reactant into smaller particles
breaking a solid reactant into smaller particles increases the number of particles available for collision
the average rate of a reaction ____ as the reaction proceeds
increases or decreases?
decreases
decreases kasi as the rxn proceeds, nababawasan conc. ng reactants
lower conc. of reactants leads to lower rxn rate
enumerate the formula for rate law given the substance A
rate = k[A]x
k = rate constant; x = rxn order; [ ] = conc.; A = reactant A
rate is directly proportional to the concentration of reactant
what law expresses the relationship of the rate of rxn to the rate constant and the conc. of the reactants raised to its rxn order
rate law
what do you call the reaction by which the rate does not vary with the increase or decrease in the concentration of the reactants?
zero-order reaction
rate of rxn is independent of all reactant concentrations
what reaction can be defined as a chemical reaction for which the reaction rate is entirely dependent on the concentration of only one reactant?
if conc. is doubled, the rxn rate is also doubled
first-order reaction
what reaction is one whose rate is proportional to the square of the concentration of one reactant? It also has a reaction rate that is proportional to the product of the concentrations of two reactants
if conc. is doubled, the rxn rate is quadrupled
second-order reaction
in the case of multiple reaction steps, in what step will the rate depend?
slow step or fast step?
slow step; the rxn rate will always depend sa slow step
in a rxn, what do you call something that is consumed first then produced later on as a final product?
first appears as a reactant then as a product
catalyst
in a rxn, what do you call something that is produced first then is consumed later on?
first appears as a product then as a reactant
intermediate
what do you call the time it takes for a conc. of a reactant to decrease by half of its original amount?
time it takes for half of the reactant to be converted to product
half-life
half-life formula for zero-order reaction
t1/2 = [A]i/2k
half-life formula for first-order reaction
t1/2 = ln2/k
half-life formula for second-order reaction
1/k[A]i
T or F?
a half-life of a first-order reaction depends on initial concentration of a reactant
False; given the formula ln2/k, a first-order reaction does not depend on the initial conc. of a reactant
only first & second-order rxns are dependent on initial conc. (reactant)
is half-life dependent on the rate constant for all reaction orders?
yes or no
yes; also, since rate constant k is found on the denominator of every formula for half-life, ↑K ↓t1/2
rate constant k is dependent on where?
activation energy and temperature
Integrated Rate Law formula for 0-order rxns
[A]f = -kt + [A]i
notice: k is negative, therefore slope is negative (➘)
Integrated Rate Law formula for 1st-order rxns
ln[A]f = -kt + ln[A]i
notice: k is negative, therefore slope is negative (➘)
Integrated Rate Law formula for 2nd-order rxns
1/[A]f = kt + 1/[A]i
notice: k is positive, therefore slope is positive (➚)
↑ or ↓ rxn rate?
increase in temp
↑ rxn rate?
↑temp = ↑kinetic energy = ↑collision = ↑rxn rate
enumerate arrhenius equation
(be familiar lang daw but no solving regarding this (hopefully))
ln(k) = -Ea/RT + ln(A)
or
k = Ae-Ea/RT
wherein: k = rate constant, A = collision frequency, -Ea = activation energy, R = gas constant (8.314 kJ/mol), T = abs temp, e = euler’s number
what do you call the species not directly involved in a rxn, but speeds it up?
catalyst
what increases the rate by lowering activation energy of the rxn by providing alternative pathways for the rxn?
catalyst
there are 3 types of catalysts, what are they?
- heterogenous
- homogenous
- enzyme
type of catalyst wherein the catalyst and reactants are of different phases
heterogenous catalyst
type of catalyst wherein catalysts and reactants are of the same phase
faster since they r in the same phase
homogenous catalyst
this type of catalyst involves enzymes that have active sites that specifically bind to substrates
enzyme
