UNIT#07 REACTION KINETICS Flashcards
Which one of the following is correct about the following reaction if iron is not 100% pure?
Very slow reaction
Which of the following reactions is usually slow?
Organic substitution reaction
For a chemical reaction to occur?
Reacting molecules must be properly oriented and energy and energy more than or equal to Ea
The increase in reaction rate as a result of an increase in temperature from 10K to 100K is;
512
(➡2^ΔT/10)
By increasing the concentration of reactant,s the rate of reaction____
Increases
The rate of a reaction involving ions can be studied by:
Electrical Conductivity Method
Which method for rate determination is applicable to reactions in solutions, where there are changes in refractive indexes of the substances taking part in the chemical reaction:
Refractometric method
The specific rate constant of a chemical reaction is the rate of the reaction when the concentration of the reactant is;
Equal to unity
The unit of the rate constant of second order reaction is;
mole-1 dm+3 sec-1
The 2nd order reaction becomes 1st order when:
One of the reactants is in large excess
The half-life time for a 1st order decomposition of a substance dissolved in CCl4 is 2.5 hours at 30°C. The amount of substance left after 10 hours if the initial weight of a substance is 160g.
10g
(Number of half-life=Total Time/Half-life)
Hydrolysis of ethyl acetate into acetic acid and ethanol in the presence of mineral acid is
Pseudo 1st Order Reaction
For a reaction A + 2B ➡C, the rate is given by Ratek[A][B], hence the order of the reaction is;
2
For a chemical reaction A➡B, the rate of reaction doubles when the concentration of A is increased four times. The order of reaction for A is;
Half
What will be the order of reaction if doubling the concentration of a reactant increases the rate by a factor of 4 and tripling the concentration of a reactant by a factor of 9
2
The rate law of a reaction is, rate= k[A]2[B]. On doubling the concentration of both A and B, the rate of reaction increases ___ time.
8
For the reaction A + B➡C+D, doubling the concentration of both the reactants increases the reaction rate by 8 times and doubling the initial concentration of only B simply doubles the reaction rate. The rate law for the reaction is;
Rate=k[A]2[B}
The rate of reaction 2X+Y➡Product
Rate=k[X]2[Y] if X is in large excess, the order of the reaction is;
1st
For the 1st order decomposition reaction, 2N2O5➡2N2O4 +O2 the half-life is given by:
0.693/k
The half-life period of zero order reaction is equal to;
a/2K
(➡For zero order reaction, half-life period is directly proportional to the initial concentration of reactants)
For which of the reaction, the half-life is inversely proportional to the initial concentration of reactants
2nd Order
If ‘a’ is the initial concentration of the reactant then the half-life period of the reaction of nth order is directly proportional to;
a^1-n
For the first-order reaction, the half-life is 14 sec. The time requires for the initial concentration to reduce to 1/8th of its value to:
42 sec
The rate constant of a reaction is 3x10^03 moldm^-3sec^-1. The order of reaction is;
0
The activation energy of the reaction
Required for effective collision
Ea appears as a potential energy hill between ___ for carrying out the reaction.
Reactants and the Products
If Ef and Er are the activation energies of forwarding and reverse reactions. The reaction is known to be exothermic then:
Ef < Er
For an endothermic reaction A➡B, the activation energy of the forwarding reaction is 15 kcal mol-1 and the enthalpy change of a reaction is 5 kcal mol-1. The activation energy for reverse reaction B➡A is:
10 kcal mole-1
Which one is the assumption o collision theory of reaction rate?
➡During a chemical reaction the particles must collide
➡Reaction between the colliding particles can only take place if upon collision theory
➡Only those collisions are effective and take place in the proper orientation
If the energy of the activated complex lies close to the energy of reactants, it means that the reaction is;
➡Exothermic
➡Fast
The activation energy for a simple chemical reaction A➡B is Ea in the forwarding direction. The activation energy for reverse reaction;
➡Can be less than
➡More than Ea
When the potential energy of the transition state is very high, then which one of the following results is applicable
➡High activation energy
➡Slow Reaction
Which of the following best explains the effects of a catalyst on the rate of a reversible reaction
It provides a new reaction path with a lower activation energy
What is the correct relation between rate and activation energy
Rate ∝ 1/ Ea
Concentrated sugar solution undergoes hydrolysis into glucose and fructose by an enzyme:
Invertase
Which of the followings is correct about enzyme catalysts
➡These are in the pure crystalline state
➡The activity of enzyme catalyst is inhibited by poison
➡Enzyme catalytic reaction has the maximum rate at optimum temperature
The reaction rate in the forwarding direction decreases with the passage of time because:
The concentration of reactants decreases
An activated complex is formed due to;
Effective collision
The chemical reactivities of elements depend upon their characteristics electronic:
Configurations
Activated Complex has;
High Potential Energy
Catalyst can:
Increase the rate of reaction
The rate of reaction in gases is best described as:
Δp/Δt
The energy required to start a reaction is called;
Activation energy
The number of reacting molecules which changes their concentration chemical change is called;
Order of reaction
Drawing a graph between concentration change with time gives a:
Parabola
Rate = k[NO2], the order of this reaction is;
One
With the passage of time rate of reaction always;
Decreases
Hydrolysis of tertiary butyl bromide is:
Pseudo First Order
If a graph is plotted with concentration data of a reaction in a chemical reaction the curve is;
Falling
Spectrum is the visual display or ___ of component of white light when it is passed through a prism.
Dispersion
After one half-life, the mass of the substance becomes;
Half
The activated state is:
➡Least Stable
➡Most Energetic
In spectrometry, the spectrometer can analyze
Atom
The change in volume depends on:
Initial and Final states
When the rate o reaction is measured by the amount of radiation absorbed, it is called;
Spectrometry
If the time interval is very small for determining the rate of reaction the values of the average and instantaneous rate
Very close to each other
As reaction starts instantaneous rate is:
Higher than the average rate
The activated complex is a reaction that has;
PE max
When the colliding molecules come closer to each other. It _____ to go to transition :
Slows down
The half-life period for a first-order reaction is independent of;
The initial concentration of the compound
The reaction which is completed in steps must contain
➡Rate determining step
➡Slowest Step
Specific rate constant is also called
Velocity constant
For third order reaction, rate cosntant has units:
mol^-2 dm^6 s^-1
(concentration)^n-1
Slowest step in the reaction is called:
Rate determining step
A certain reaction has the rate equation, Rate=k[A][B]2. The rate is 2.5x10^-3 mol dm-3s-1. When [A] is 0.2 mol dm-3 and [B] is 0.050 mole dm-3. Calculate the numerical value of the rate constant.
5.0
The units of second order rate constant are usually expressed as:
mol-1 dm3 s-1
The rate expression of a reaction is, Rate = k[A][B]2. What happens to rate of reaction if concentrations of A and B are doubled?
Increased eight times
One of the following is not a physical method for determination of rate of reation;
Titrimetry
Dilatometric method is useful for the reaction that involves:
small volume change in solution
Which property of liquid is measured by polarimeter
Optical Activity
Generally by increasing temperature rate of chemical reaction increase. It is due to;
Greater number of molecule having activation energy
Arrhenius equation describes the effect of:
Temperature on rate of reaction
Following is an exothermic reaction. Which is correct statement:
➡Rate of reaction will increase by increasing temperature
Which of the followings is pseudo first order reaction:
➡Acid Catalyzed hydrolysis of an ester
➡Hydrolysis of tertiary butyl bromide
In Rate=k[A][B] the second order reaction becomes _____ if [A] is in large excess
Pseudo First Order
For a reaction like X + 2Y ➡Z Rate=k[X]0[Y]2
If concentration of X and Y is doubled, then rate of reaction increase
4 times
On increasing the temperature ,the rate of reaction increases mainly because;
Collision frequency increases
The collision frequency is:
Proportional to the concentration of reacting molceuls
Which statement is incorrect about activated complex
➡Short Lived❌
➡Maximum Energy❌
➡Unstable combination of atoms❌
➡Less energy than Ea✅
In a reaction 2X+Y ➡M+N
If the concentration of Y kept constant and that of X is tripled. The reaction will be;
increase 9 times
A reaction has equal activation energy for forward and backward reaction. Which statement is coorect:
➡Reaction is zero order❌
➡Enthalpy change is zero✅
➡Product has less energy than reactants❌
➡No Catalyst has been used❌
The number of colliding molecules of different gases calculated from kinetic theory of gases is of magnitude of ___ per litre per second.
10³²
The value of activation energy of chemical reaction is primarily determine by:
Number of collisions per unit time
The value of activation energy is primarily determined by:
Effective Collision
For endothermic reaction, Ea is activation energy in Kj/mole. The maximum value of enthalpy of reaction (ΔH) will be:
Less than Ea
Which is the correct expression of Arrhenius equation;
k = Ae^-Ea/RT
The number of atoms or molecules whose concentration determines the rate of a chemical reaction is called the;
Order of the reaction
The order of reaction may be determined by;
➡Differential
➡Half-Life Method
➡Graphical Method
If rate constant for any reacton is equal to rate of reaction at all concentration. Then the order of reaction will be;
Zero
The rate for the reaction is:
Rate = k[A][B]2/3.
The order of reaction is;
5/3
Factor which does not generally affect the rate of reaction;
Pressure
The rate of chemical reaction roughly doubles for every 10°C rise of temperature. If temperature is raised by 20°C, the rate may become;
4 times
The units of slope are in:
Per Kelvin
The rate of reaction can be increased i general by all of the following factors except:
By increasing activation energy
The rate of reaction decreases how many times when tempearture drops rom 150K to 120K
Eight
Rate of chemical reaction increase rapidly even for small increase in temperature because of rapid increase in the:
Fraction of molecuels with energy more than activation energy
Which will change for first order reaction with time:
Rate of reaction
All are slow processes except:
Reaction of AgNO3 with NaCl
(Ionic solutions react astly)
On the basis of given values Ksp, which sparingly soluble salt is least soluble in water:
Ksp = =2x 10^6
If “X” moles of Ag2CrO4 are dissolved in water to produce a saturated solution then Ksp will be:
4x3
Ksp values of four salts are given, which is more soluble in water:
10^-10
(Greater the Ksp, Greater the solubility of salt)
The solubility product of an ionic compound AB2 is 32 x 10^-9 mol3 dm-9. The maximum concentration of A+2 ion is:
2 x 10^-3 mol. dm-3
AgNO3 + NaCl ➡AgCl + NaNO3 , which one is correct about a given reaction;
It is a very fast reaction
The unit of the rate constant is the same as that of the rate reaction in
Zero order reaction
The rate of reaction is doubled for every 10°C rises in temperature. The increase in reaction rate as a result of temperature rise from 10°C to 100°C is;
512
The mathematical relation between the rate of reactions and the concentration of the reactants is known as the
Rate Law Equation
AgNO3 + NaCl ➡AgCl + NaNO3, which one is correct about given reaction.
It is a very fast reaction
The unit of the rate constant is the same as that of the rate of reaction in:
Zero order Reaction
The rate of reaction is doubled for every 10°C rises in temperature. The increase in reaction rate as a result of temperature rise from 10°C to 100°C is;
512
The mathematical relation between the rate of reaction and the concentration o the reactants is known as the:
Rate law equation
If 75% of any given amount of radioactive element disintegrates in 60 min. The half-life of a radioactive element is:
30 min
(k= 2.303/t log 100/100-x
t1/2 = 0.693/k)
The energy of activated complex is:
➡Greater than reactants
➡Greater than products
The rate of reaction depends upon:
Molar concentration
For a first-order reaction, the half-life period is independent of;
Initial Concentration
If the rate of the reaction is equal to the rate constant, the rate of reaction is:
0
Which of the following is incorrect about the rate of reaction?
➡It is calculated experimentally❌
➡It is the sum of powers of concentration in the rate law equation❌
➡The order of reaction cannot be fractional✅
➡There is not necessarily a connection between order and stoichiometry of a reaction❌
For the reaction A+B+C ➡Product, Rate =k[A]^1/2 [B]^1/3 [C]. The order of the reaction is:
11/6
The half-life period of a first-order reaction is 15 minutes. The amount of substance left after one hour will be:
1/16
For an exothermic reaction, the activation energy of the forward reaction is 70kJ/mol and the enthalpy change of a reaction is 30 kJ/mol. The activation energy for the reverse reaction is;
100 kJ/mol
According to Arrhenius’s equation, a straight line is to be obtained by plotting the logarithm of the rate constant against.
1/T
A mixture of H and Cl2 will react twice as fast if the partial pressure of H2 or Cl2 is
Increase from 0.5 to 1atm
Select the suitable catalyst for the given reaction:
HCOOH ➡ H2O + CO2
Cu
The equilibrium expression or reaction is Kc= 4x^2 V / (a-2x)^2(b-x) for a gaseous phase reaction, then which of the following is true?
Kp < Kc
