Chemical Reaction rates
What is the unit for Reaction Rate (rmb. rr= change in concentration/change in time)
M/s or
mol/(Ls)
or molL-1s-1
Given the following reaction:
NO+O3⟶NO2+O2
write the rate law interms of [NO], [O3], [NO2], [O2], m,n, K, and rate
what is the overall order of the reaction? write it interms of m and n
rate = k [NO]n[O3]m
Over order = m+n
What is the point of the arrhenius equation? As in explain what it defines. what does it relate?
It relates a random rate constant to more realistic values that affect a reaction, like temperature and activation energy, and the frequency factor. Also it relates it to more known constants like R.
Can a catalyst can make a non-spontaneous reaction spontaneous?
What does a catalyst do?
No it cant. catalyst doesnot affect delta G. It only affects activation energy, reduces it. So a catalyst only speeds up a spontaneous reaction.
Given the following reaction:
aA + bB -----> cC + dD
Write the general reaction rate equation for it.
(what is the overall reaction rate of this equation)
- [A]/at = - [B]/bt = [C]/ct = [B]/bt
RMB its change in concentration/change in time
Given a second-order reaction:
A+B ------> products
and a rate law:
rate = K [A] [B]
But A is present in excess, to the point that the concentration of A changes negligibly as the reaction process.
How can the rate law be simplified?
Does the simplified rate law have a name?
can be simplified to
rate = K' [B] where
K' = K [A] since [A] stays constant
that is called a pseudo-first-order reaction
Write the Arrihinus Equation and explain each component in the equation. Mention their units when possible or mention if it is unit less.
k=Ae(-Ea∕RT)
k is the rate constant, unit depends on reaction order
A is frequency factor, Expresses probability that orientation of the molecules is appropriate for a reaction to occur. Units are complicated. ask me to explain. rmb to show the screen shots. don't take my word for it though cuz my reference is the internet
Temperature is in kelvin, activation energy is in j/mol, R is 8.314 J/mol K
What are the 2 types of catalyst. Name them.How are they different?
•Homogeneous catalyst (A catalyst in the same phase as the reactants)
Heterogeneous catalyst (•A catalyst in a different phase than the reactants)
Name the 2 physical & Chemical Features thataffect Reaction Rate
(so total 2, not 2 physical 2 chemical)
Smaller Particle Size React Faster than bigger particle size,
More reactive element has a higher reaction rate than less reactive element (eg. lithium reacts faster than beryllium
Worked Example 12.3
Shown on the slide containing 12.3
What are the 3 requirements that have to be fulfilled for a reaction to happen, according to the collision theory
1) A collision between reactants needs to happen for the reaction to happen
2)There needs to be enough energy in each collision for the reaction to happen
3) The molecules need to be in the appropriate orientation for the reaction to occur
Name the 5 "macro-factors" affecting reaction rate. How does it affect reaction rate? Why does it affect reaction rate?
For the lack of a better word these "macro-factors" are Concentration, Temperature, Pressure, Catalyst.
increasing conc. increases RR, cuz higher no. of collisions
same for temp. and pressure
adding a catalyst reduces activation energy and increases RR
30. from text book
The annual production of HNO3 in 2013 was 60 million metric tons Most of that was prepared by the following sequence of reactions, each run in a separate reaction vessel.
(a) 4NH3(g)+5O2(g)⟶4NO(g)+6H2O(g)
(b) 2NO(g)+O2(g)⟶2NO2(g)
(c) 3NO2(g)+H2O(l)⟶2HNO3(aq)+NO(g)
The first reaction is run by burning ammonia in air over a platinum catalyst. This reaction is fast. The reaction in equation (c) is also fast. The second reaction limits the rate at which nitric acid can be prepared from ammonia. If equation (b) is second order in NO and first order in O2.
What is the rate of formation of NO2 when the oxygen concentration is 0.50 M and the nitric oxide concentration is 0.75 M? The rate constant for the reaction is 5.8 × 10−6 L2mol−2s−1.
I will work on it with you. there was no answer given in text book
worked example 12.13 b) and c)
in the same slides with the work problem
a) What is the difference between average rate, initial rate, and instantaneous rate?
b) In the nuclear industry, chlorine trifluoride is used to prepare uranium hexafluoride, a volatile compound of uranium used in the separation of uranium isotopes. Chlorine trifluoride is prepared by the reaction Cl2(g)+3F2(g)⟶2ClF3(g)
Write the equation that relates the rate expressions for this reaction in terms of the disappearance of Cl2 and F2 and the formation of ClF3.
a)relating to the graph and the calculated slope. *RMB to draw them.
b) [ClF3]/2t = - [Cl2]/t = - [F2]/3t
Worked Example 12.4
in the slides with worked example 12.4
Worked Example 12.6, if you don't want to plot just tell me how you would go about doing it.
in the slides after 12.6
qn 64 from text book.
The element Co exists in two oxidation states, Co(II) and Co(III), and the ions form many complexes. The rate at which one of the complexes of Co(III) was reduced by Fe(II) in water was measured. Determine the activation energy of the reaction from the following data: