Chemical kinetics Flashcards
Feasibility of a chemical reaction can be predicted by
Thermodynamics
Extent of a chemical reaction can be predicted by
Chemical equilibrium
Assertion : diamond cannot be converted to graphite
Reason : diamond is forever
The assertion and reason is false diamond can be converted to graphite
The rate is always multiplied with -1 to make it a positive quantity
True
Unit of rate is
Concentration time inverse/ atm s inverse
Statement 1: Rate of a reaction depends on stochiometric coefficient
Statement 2: rate of any species will be fixed value under given condition
Both statements are correct
The rate of the reaction is CHCL3 +CL2 = CCL4 + HCL
Rate = k [ CHCl3] [ Cl2]^1/2
The rate ofthe reaction is CH3COOC2H5 + H2O = CH3COOH + C2H5OH
Rate = k[ CH3COOC2H5] ^1 [H20]^0
Assertion: rate law of a reaction cannot be determined by mere looking of a chemical reaction
Reason : it must be obtained experimentally
Both assertion and reason are true
Example of consecutive reaction is
Oxidation of ethane
Example of reverse reaction and side reaction
Nitration of phenol to yield o nitro phenol and p nitro phenol
Statement1: the reaction with collision of three or more molecules are rare to proceed
Statement2 : 2NO +O2 = 2NO2
Both statements are correct
The order of the given reaction is KCLO3 + 6FeSO4 +3 H2SO4 = KCL +3 Fe2(SO4)3 +3H20
2
In Decomposition of hydrogen peroxide the rate determining step is
H2O2 + I^- = H2O + IO ^-
Statement1: order is applicable to elementary as well as complex Rn but
Statement2 : molecularity is applicable only to elementary rn
Both statements are true
Factors influencing the rate of the reaction is
Concentration of reactant
Rate expression and rate constant
Order of a reaction
Molecularity of a reaction
The integrated rate eq for 1st order rn
Is
[R] = -KT +[ Ro]
Statement 1: some enzyme catalyzed rn and reaction which occur on the metal surface are examples of zero order rn
Statement2: zero order reactions are very rare
Both statements are true
Why is 2 NH3 = N2 + 3H2 (in presence of Pt catalyst and 1130 K) a zero order rn ?
This reaction is catalyzed by Pt , at high pressure the metal surface is saturated with gas molecules and further changes in reaction condition cannot alter the amountt of ammonia making the rate of reaction concentration independent
Examples of zero order rn
NH3 = N2 + H2 ( in presence of Pt and at 1130K)
Thermal Decomposition of HI on gold surface
The integrated form of 1st order reactions are
[R] = [Ro] e ^ (-kt)
K = 2.303 /t log [ Ro]/ [ R]
Examples of first order reaction
Hydrogenation of ethene
All artificial and natural radioactive decay of unstable nuclei
Decomposition of N2O5 and N2O
For zero order reaction half life is
[Ro] /2 k
For first order reaction half life is
0.693 / k
Statement 1: straight line plot of zero order rn Is btw [ R] vs t
Statement 2: straight line plot of 1st order rn Is btw ln[ R] vs t
Both statement are correct
Order of a reaction can be altered by conditions
True
Examples of pseudo first order rn Is
Inversion of cane sugar
Hydrolysis of ethyl acetate in presenceof Excess water
For a chemical reaction the rate constant is doubled for every
10° rise in temp
The temp dependence of a chemical reaction is explained by arrhenius eq
K = Ae ^ (- Ea / RT) where A is arrhenius factor or frequency factor
Activation energy is measured in
Joules per mole
Statement 1 : all molecules of reacting species have same kinetic energy
Statement 2 : that is why Ludwig boltzmann and James Clark maxwell used to statistics to predict the behavior of large number of molecules
Statement 1 is incorrect while statement 2 I correct
Increasingthe temp increases the fraction of molecules which collide with more than Ea
True
Arrhenius eq in log form is
Log k2/ k1 = Ea /2.303 R [ T2- T1/ T1T2]
Explain the action of catalyst
The catalyst take part in chemical reaction by forming temporary bonds with the rectant which form an intermediate complex which has transitory existence and Decomposes to yield products
Assertion : catalyst does not alter Gibbs energy
Reason : it does not catalyse non Spontaneous rn
Both assertion and reason are true but it’s not the reson of assertion
Collision theory is based on
Kinetic theory of gases
Define Collision frequency
It is number of collision per sec per unit volume of a reaction mixture
Rate according to collision theory
Rate =P Z e^(- Ea/RT) where p is probability factor or steric factor
