Chap 13 Flashcards
(27 cards)
averate rate formula?
🔺️ [M]/ 🔺️ time (t)
what gives instantaneous rate?
slope of tangent line on curve
what is intial rate
the highest concentration of reactants. its where rate is fastest.
example of reaction rate:
N2 + 3H2 —> 2NH3
-🔺️[N2]/🔺️t = -1/3🔺️[H2]/🔺️t = +1/2🔺️[NH3]/🔺️t
what happens to rate if we double a reactant?
what if we double a product?
rate will double for both. howveer you must do experiments to prove.
what is a rate law?
an equation that describes the dependency of the reaction rate to the concentration of reactants.
rate=k[A]^m[B]^n
what is reaction order?
experimentally determined number describing the dependency of initial reaction rate on the initial reactant concentration ex:first order, second order, third etc
what is the overal reaction order?
sum of exponents of concentration terms in the rate law
do handheld flashcard example 1
do handheld flashcard example 2
how to calculate k?
must get rate law. once you have it select one experiment from the table and plug in the numbers and solve for k.
what are the units of k?
1st order: s -¹
2nd order: M -¹ s -¹
3rd order: M -² s -¹
what do the graphs of zero, first, and second order integrated rate laws look like?
zero: harsh slope down (-k)
first: slope down (-k)
second: positive slope (+k)
2N2O5 —> 4NO2 + O2 is first order rxn and k= 6.32 x 10 -⁴ s -¹. how much N2O5 remains in solution after 1h if the initial concentration of N2O5 was 0.50mol/L?
ln[N2O5]t = -kt + ln[N2O5]0
if ln[N2O5]0 = ln(0.50M) and -k= -6.32 x10 -⁴ and t= 3600s cause hr->s. THEN
ln[N2O5]t= -2.28 - 0.693
ln[x] = -2.973 THEN
e -².⁹⁷³ so x=0.051 M
what is a half life?
the time interval for the reactant concentration to decrease by half.
the radioactive isotope ³²P decays by first-order kinetics and has a half life of 14.3 days. how long does it take for 95% of a sample of ³²P to decay? halflife form= t1/2= 0.693/k
pkug into half life: 14.3=0.693/k
k= 0.0485
INITAL goes away in halflife problem. ln[.05]t= -(.0485)t
= 61.8 days
what is an activation complex/transistoon state?
when bonds are brekaing and forming at same time in rxn. VERY UNSTABLE. energy needed to be stable
low Ea = large k equals what
fast forward rxn
high Ea = small k equals what
slow forward rxn
do handheld flash card 3
do handheld flashacrd 4
what is rxn mechanism?
a set of steps that describe how an overall rxn occurs at the molecular level. ex elementary steps
what is elementary step?
a chemical rxn that defunes a single molecular process(single step) THE RATE LAW FOR ELEMENTARY STEP WILL BE BASED ON STOICH
rate is only effcected by the _______ step
SLOWEST
