1AA3 Chemistry - Test 2 Review Exam questions
and answers Graded A+
in a zero order reaction, what is the relationship between the rate and the
concentration of reactant? - ✅✅V initial = k[A]^0 = k = constant
> the rate law is not affected by the concentration
> no change in the initial rate
what are the units of k for a zero-order reaction? - ✅✅concentration/time
ex: M/s
give an example of a zero-order process - ✅✅evaporation/sublimation with
constant surface area
what is a pseudo zero-order reaction? - ✅✅a reaction where catalyst or
enzyme is saturated with reactants (ex. drug/alcohol metabolism)
> not actually zero order but appearing to be
> adding more substrate does not make the reaction go faster because enzymes
cannot work any faster
give 2 key concepts about zero-order reactions. - ✅✅1. rate = rate constant (k)
2. true zero-order reactions are rare
what is the integrated rate law? - ✅✅[A]t = [A]0 - kt
,nucleophilic substitution - ✅✅an electronegative atom or group bonded to a
carbon atom is replaced by another
> can be first or second order overall depending on chemical structure
> run experiments to tell what the order actually is
how do you increase the rate of reaction? - ✅✅increase the concentration of
one of the reactants
rate determining step - ✅✅tells you what the rate law is going to be
what is the order for a reaction with only one molecule? - ✅✅first order
Sn1 reaction - ✅✅S = substitution reaction
n = nucleophilic (something is looking for a positive charge on the nucleus)
1 = one species in the rate-limiting step
what are the units for k in a first order reaction? - ✅✅1/time (ex. s^-1)
name some characteristics of k. - ✅✅1. constant regardless of concentration
2. depends on the identity of the reactants, temperature, catalyst, and solvent
integrated rate law for first-order reactions - ✅✅> rate equation gives v at
every instant
> integrating v vs. time gives [A] consumed (or [G] formed)
> equation: ln[A]t = -kt + ln[A]0
, > ln[A] is unitless, therefore k is unit less
what can be said about the half lives of first-order reactions? - ✅✅they are
constant
> t1/2 = ln 2/k or t1/2 = 0.693/k
what is the integrated rate law for reactions involving gases? - ✅✅ln(Pa)t/(Pa)0
= -kt
what is the main difference between the differential rate law and the integrated
rate law? - ✅✅> they are equivalent but used in different circumstances
> for diff. rate law, the rate changes as a function of [ ]
> integrated rate law expresses how [ ] of the reactants or products depend on
time
what are the key concepts of first order reactions? - ✅✅> rate is proportional
to [A]
> t1/2 = constant
>rate and integrated rate equations
Sn2 reaction - ✅✅> second-order reaction
S = substitution
n = nucleophilic
2 = 2 species in the rate limiting step
and answers Graded A+
in a zero order reaction, what is the relationship between the rate and the
concentration of reactant? - ✅✅V initial = k[A]^0 = k = constant
> the rate law is not affected by the concentration
> no change in the initial rate
what are the units of k for a zero-order reaction? - ✅✅concentration/time
ex: M/s
give an example of a zero-order process - ✅✅evaporation/sublimation with
constant surface area
what is a pseudo zero-order reaction? - ✅✅a reaction where catalyst or
enzyme is saturated with reactants (ex. drug/alcohol metabolism)
> not actually zero order but appearing to be
> adding more substrate does not make the reaction go faster because enzymes
cannot work any faster
give 2 key concepts about zero-order reactions. - ✅✅1. rate = rate constant (k)
2. true zero-order reactions are rare
what is the integrated rate law? - ✅✅[A]t = [A]0 - kt
,nucleophilic substitution - ✅✅an electronegative atom or group bonded to a
carbon atom is replaced by another
> can be first or second order overall depending on chemical structure
> run experiments to tell what the order actually is
how do you increase the rate of reaction? - ✅✅increase the concentration of
one of the reactants
rate determining step - ✅✅tells you what the rate law is going to be
what is the order for a reaction with only one molecule? - ✅✅first order
Sn1 reaction - ✅✅S = substitution reaction
n = nucleophilic (something is looking for a positive charge on the nucleus)
1 = one species in the rate-limiting step
what are the units for k in a first order reaction? - ✅✅1/time (ex. s^-1)
name some characteristics of k. - ✅✅1. constant regardless of concentration
2. depends on the identity of the reactants, temperature, catalyst, and solvent
integrated rate law for first-order reactions - ✅✅> rate equation gives v at
every instant
> integrating v vs. time gives [A] consumed (or [G] formed)
> equation: ln[A]t = -kt + ln[A]0
, > ln[A] is unitless, therefore k is unit less
what can be said about the half lives of first-order reactions? - ✅✅they are
constant
> t1/2 = ln 2/k or t1/2 = 0.693/k
what is the integrated rate law for reactions involving gases? - ✅✅ln(Pa)t/(Pa)0
= -kt
what is the main difference between the differential rate law and the integrated
rate law? - ✅✅> they are equivalent but used in different circumstances
> for diff. rate law, the rate changes as a function of [ ]
> integrated rate law expresses how [ ] of the reactants or products depend on
time
what are the key concepts of first order reactions? - ✅✅> rate is proportional
to [A]
> t1/2 = constant
>rate and integrated rate equations
Sn2 reaction - ✅✅> second-order reaction
S = substitution
n = nucleophilic
2 = 2 species in the rate limiting step
