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| 24651. |
The rate of chemical reaction depends on the nature of chemical reactions, because: |
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Answer» The threshold ENERGY level DIFFERS from one reaction to another |
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| 24652. |
The rate of change in concentration of C in the reaction 2A+B to 2C +3D was 1.0 molL^(-1)S^(-1). Calculate the reaction rate as well as rate of change of concentration of A,B, and D |
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Answer» Solution :We have, `-(1)/(2)(d[A])/(dt)=(-d[B])/(dt)=(1)/(2)(d[C ])/(dt)=(1)/(3)(d[D])/(dt)=` rate of reaction `:. (d[C ])/(dt)=1.0 mol L^(-1)sec^(-1)` `:.-(d[A])/(dt)=(d[C])/(dt)=1.0molL^(-1)sec^(-1)` `-(d[B])/(dt)=(1)/(2)(d[C])/(dt)=(1)/(2)=0.5molL^(-1)sec^(-1)` `(d[D])/(dt)=(3)/(2)(d[C])/(dt)=(3)/(2)xx1=1.5mol L^(-1)sec^(-1)` Rate `=(1)/(2)(d[C])/(dt)=(1)/(2)xx1=0.5molL^(-1)sec^(-1)` |
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| 24653. |
The rate of change of concentration of (A) for reaction A to B is given by -(d[A])/(dt)=k[A]^(1//3) Derive expression for half-life period of the reaction. |
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Answer» Solution :`-(d[A])/(dt)=K[A]^(1//3):.-int(d[A])/([A]^(1//3))=k" dt or "-int[A]^(-1//3)d[A]=k" dt "-(3)/(2)[A]^(2//3)=KT+C[int X^(n)dx=(x^(n+1))/(n+1)]""...(i)` At `t=0,[A]=[A_(0)]:. -(3)/(2)[A_(0)]^(2//3)=C` Substituting the value of C in eqn. (i), `-(3)/(2)[A]^(2//3)=kt-(3)/(2)[A_(0)]^(2//3)" or "kt=(3)/(2)[A_(0)]^(2//3)-(3)/(2)[A]^(2//3)=(3)/(2){[A_(0)]^(2//3)-[A]^(2//3)}` At `t=t_(1//2),[A]=([A_(0)])/(2)` `:.kt_(1//2)=(3)/(2){[A_(0)]^(2//3)-[(A_(0))/(2)]^(2//3)}` or `t_(1//2)=(3)/(2k)[A_(0)]^(2//3)[1-(1)/((2)^(2//3))]=(3[A_(0)]^(2//3))/(2k)[((2)^(2//3)-1)/((2)^(2//3))]=(3[A_(0)]^(2//3))/(k)[((2)^(2//3)-1)/(2^(5//3))]` |
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| 24654. |
The rate of chemical reaction at constant temperature is proportional to |
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Answer» The amount of products formed |
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| 24655. |
The rate of a reaction that not involve gases is not dependent on |
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Answer» Pressure |
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| 24656. |
The rate of a reaction that not involve gases is not dependent on: |
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Answer» PRESSURE |
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| 24657. |
The rate of a reaction qudruples when the temperature changes from 293 K to 313 K.Calculation the energy of activation of the reaction assuming that it does not change with temperature. |
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Answer» SOLUTION :`T-(1)`=293 K rate=`r_(1)` means `k_(1)` and `E_(a)`=(?) `T_(2)`=313K rate =`r_(2)=4r_(1)` `k_(2)=4k_(1)` log `(K_(2))/(k_(1))`=log `(4k_(1))/(k_(1))` =log 4 log `(k_(2))/(k_(1))=(E_(a))/(2.303xx8.314)((313-293)/(313xx293))` `therefore 0.6021=(E_(a))/(2.303xx8.314)((20)/(313xx293))` `therefore E_(a)=(0.6021xx2.303xx8.314xx313xx293)/(20)` |
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| 24658. |
The rate of a reaction quadruples when the tamperature changes from 300 to 310k. The activation energy of this reaction is : (Assume activation energy and pre-exponential factor are independent of temperature , In2=0.693, R=8.314J*mol^(-1)*K^(-1)) |
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Answer» `107.2kJ*mol^(-1)` `IN4=(E_(a))/(8,314)((310-300)/(310times300))` `2In2=(E_(a))/(8,314)((310-300)/(310times300))` `E_(a)=107.2kJ*mol^(-1)` |
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| 24659. |
The rate of a reaction quadruples when the temperature changes from 293 K to 313 K. Calculate the energy of activation of the reaction, assuming that it does not change with temperature. |
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Answer» SOLUTION :Using the relation `"log"(k_(2))/(k_(1))=(E_(a))/(2.303R)[(T_(2)-T_(1))/(T_(1)T_(2))]`. In this CASE, `k_(2)=4k_(1)` `therefore "log"(4k_(1))/(k_(1))=(E_(a))/(2.303R)[(T_(2)-T_(1))/(T_(1)T_(2))]` Substituting the VALUES, we get `log 4=(E_(a))/(2.303x8.314)[(313-293)/(293xx313)] or 0.6021=(E_(a))/(19.147) xx (20)/(91709)` or `E_(a)=(0.6021xx19.147xx91709)/(20) or E_(a)=52862"J mol"^(-1)=52.862"kJ mol"^(-1)`. |
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| 24660. |
The rate of a reaction may be expressed by the following different ways : (1)/(2) (d[X])/(dt)=-(1)/(3) (d[Y])/(dt)=-(d[Z])/(dt) The reaction is : |
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Answer» `3 Y +Z rarr2X ` |
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| 24661. |
The rate of a reaction is expressed in different ways as follows +(1)/(2)(d[C])/(dt)=-(1)/(5)(d[D])/(dt)=+(1)/(3)(d[A])/(dt)=-(d[B])/(dt) The reaction is |
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Answer» `4A+B to 2C+3D` |
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| 24662. |
The rateof a reactionis givenas , rate= k[X]^(3//2) [Y]^(-1//2) Whatis the orderof thereaction ? If Y is takenlarge in excess , writethe rate equation. |
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Answer» Solution :Rate LAW of the reaction is given as, rate `=k[X]^(3//2)[Y]^(-1//2)`. ORDER with respect to X is 3/2 Order with respect to Y is -1/2 Over all order of the reaction `=3//2-1//2=1` If Y is taken large in excess, the rate is INDEPENDENT of its concentration, as [Y] is taken as constant during the course of reaction. The rate EQUATION where X is isolated is rate `=k[X]^(3//2)`. |
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| 24663. |
The rate of a reaction is expressed in the units |
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Answer» L `"mol"^(-1)t^(-1)` |
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| 24664. |
The rate of a reaction is doubled when the concentration of reactant is doubled. What is the order of the reaction ? |
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Answer» two rate `PROP` CONC. Of rectant. |
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| 24665. |
The rate of a reaction is doubled for every 10^(@)C rise in temperature . The increase in reaction rate as a result of temperature rise from 10^(@) C to 100^(@)C is |
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Answer» 112 For an increase to `90^(@)C` i.e. 9 times , the rate increases by `2^(9)` times i.e. 512. |
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| 24666. |
The rate of a reaction is doubled for every 10^@C rise in temperature. The increase in rate as a result of increase in temperature from 10^@C to 100^@C is: |
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Answer» 112 |
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| 24667. |
The rate of a reaction ((dx)/(dt)) varies with nature, physical state and concentration of reactants, temperature, exposure to light and catalyst, whereas rate constant (K) varies with temperature and catalyst only. The rate constant K is given as K=Ae^(pmE_(a)//RT)where A is Arrhenius parameter or pre-exponential factor and E_(a) is energy of activation. The minimum energy required for a reaction is called threshold energy and the additional energy required by reactant molecules to attain threshold energy level is called energy of activation. At what conditions exponential factor is 1 for a reaction: |
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Answer» Infinite temperature |
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| 24668. |
The rate of a reaction gets doubled when the temperature change from 7^(@)C to 17^(@)C. By what factor will it change for the the temperature change from 17^(@)C to 27^(@)C ? |
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Answer» `1.81` |
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| 24669. |
The rate of a reaction increases to four times when the prevailing temperature is raised from 300 K to 320 K. Calculate the energy of activation of this reaction assuming that it does not change with temperature.""[R=8.314"J mol"^(-1)K^(-1)] |
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Answer» Solution :Arrhenius EQUATION relating the RATE CONSTANT and temperature is given below: `"log"(k_(2))/(k_(1))=(E_(a))/(2.303R) xx ((1)/(T_(1)) - (1)/(T_(2)))` SUBSTITUTING the values, we get `log 4= (E_(a))/(2.303xx8.314)xx ((1)/(300)-(1)/(320)) or log 4= (E_(a))/(19.147) ((20)/(300xx320))` `or E_(a)=(19.147 xx 32xx3xx0.6021)/(20)=55.336"kJ mol"^(-1)`. |
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| 24670. |
The rate of a reaction doubles when its temperature changes from 300 K to 310 K.Activation energy of such a reaction will be: (R=8.314 JK^(-1)mol^(-1) and log 2=0.301) |
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Answer» 53.6 KJ `MOL^(-1)` |
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| 24671. |
The rate of a reaction increased from 2 units to 54 units due to change in temperature from 27^(@)C to 57^(@)C. What is the approximate temperature coefficient of the reaction. |
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Answer» |
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| 24672. |
The rate of a reaction doubles when its temperature changes from 300 K to 310 K . Activation energy of such a reaction will be : (R = 8.314 JK^(-1) mol^(-1) and log2 = 0.301) |
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Answer» `53.6 kJ mol^(-1)` `(K_(2))/(K_(1)) = 2 , T_(2) = 310 K"" T_(1) = 300` K `implies ` log `2 = (-E_(a))/(2.303 XX 8.314 ) ((1)/(310) - (1)/(300))` `implies E_(a) = 53598.6` J/mol = 53.6 KJ/mol |
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| 24673. |
The rate of a reaction depends upon the temperature and is quantitatively expressed as K=Ae^(-E_(a)//RT) (i) If a graph between log K and 1/t write the expression for the slope of the reaction ? (ii) If at under different condition E_(a1)and E_(a2) are the activation energy of two reactions . If E_(a1)=40j/mol and E_(a_(2))=80j/mol. Which of the two has larger value of the rate constasnt ? |
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Answer» Solution : In `k=-(E_(a))/(RT) + In A` This equation is of the tyep y = MX+ C SLOPE` = -(E_(a))/( R)` (ii) Smaller the ACTIVATION a=energy activation energy , GREATER is the value of rate cosntant . `therefor E _(1)> K_(2)` |
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| 24674. |
The rate of a reaction doubles when its temperature changes from 300 K to 310 K. Activation energy of such a reaction will be |
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Answer» `60.5" KJ MOL"^(-1)` |
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| 24675. |
The rate of a reaction doubles for energy 10^(@)C rise of temperature. If the temperature is raised by 50^(@)C, the rate of reaction increases by about |
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Answer» 10 TIMES |
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| 24676. |
The rate of a reaction depends upon the |
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Answer» Volume |
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| 24677. |
The rate of a reaction depends upon |
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Answer» CONCENTRATION of reactant |
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| 24678. |
The rate of a reaction depends on all factors except : |
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Answer» reaction temperature |
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| 24679. |
The rate of a reaction can be increased in general by all the factors except: |
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Answer» USING a catalyst |
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| 24680. |
The rate of a reaction can be increased in general by all the factors except |
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Answer» USING a catalyst |
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| 24681. |
The rate of a reaction becomes four times when the temperature changes from 293 K to 313 K. Calculate the energy of activation (E_(a)) of the reaction aassuming that it does not change with temperature. |
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Answer» Solution :Given if rate at 293 K is R thus at 313 K rate BECOMES = 4R `LOG.(k_(2))/(k_(1)) = (E_(a))/(2.303 R)[(T_(2)-T_(1))/(T_(1) xx T_(2))]` `log.(4R)/(R ) = (E_(a))/(2.303 xx 8.314)[(313 - 298)/(293xx 313)]` `log4 = (E_(a))/(19.1471)[(20)/(91709)]` `0.6021 = (E_(a))/(19.1471)[(20)/(91709)]` `(0.6021 xx 19.1471 xx 91709)/(20) = E_(a)` `E_(a) = 52863.2177 J mol^(-1)` or `= 52.863 kJ mol^(-1)` |
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| 24682. |
The rate of a reaction becomes four times when the temperature changes from 293 K to 313 K. Calculate the energy of activation (E_(a)) of the reaction assuming that it does not change with temperature.""[R=8.314JK^(-1)"mol"^(-1), log 4=0.6021] |
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Answer» Solution :`"log"(k_(2))/(k_(1))=(E_(a))/(2.303R)[(T_(2)-T_(1))/(T_(1)T_(2))]` Substituting the values, we have `log 4=(E_(a))/(2.303xx8.314JK^(-1)"mol"^(-1))[(313K-293K)/(293K XX 313K)]` or `0.6021=(E_(a))/(19.147JK^(-1)"mol"^(-1))xx(20)/(91709K)` or `E_(a)=(0.6021xx19.147xx91709)/(20)"J mol"^(-1)=52863"J mol"^(-1)=52.86"kJ mol"^(-1)` |
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| 24683. |
The rate of a reaction at a particular temperature is r and at another temperatureis 2r. What could be approximate difference betweenthe two temperatures? |
| Answer» SOLUTION :`10^(@)` | |
| 24684. |
Therate of areactionat 600 Kis 7.5 xx 10^(5)timesthe rate ofthe samereactionat 400 K. Calculatethe energyof activationfor the reaction. |
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Answer» Fromthe hint `,(R_(2))/(R_(1))= (K_(2))/(K_(1)) = 7.5 xx 10^(5)` Initialtemperature= `T_(1)= 400 K` Finaltemperature = `T_(2) = 600 K` ENERGYOF activation`=E_(a) = ?` `log_(10).(k_(2))/(k_(1))= (E_(a) (T_(2)-T_(1)))/(2.303 R xx T_(1) xx T_(2))` `= (2.303 xx 8.314 xx 400 xx 600)/((600 -400)) log_(10)7.5 xx 10^(5)` `=(2.303 xx 8.314 xx 400 xx 600xx 5.875)/(200)` `= 135000 J mol ^(-1)=135 kJ mol^(-1)` |
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| 24685. |
The rate of a reaction 2X + Y toProducts is given by (d[Y])/(dt) = k[X]^2[Y] if X is present in large excess, the order of the reaction is |
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Answer» zero Hence , order of REACTION = 1. |
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| 24686. |
The rate of a reaction Ararr product, increases by a factor of 100, when cone, of ‘A’ is increased 10 fold. The order of the reaction is |
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Answer» 3 |
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| 24687. |
The rate of a particular reaction quadruples when the temperature changes from 293 K to 313 K. Calculate activation energy in KJ/mol. |
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Answer» Solution :`K_2//K_1`=4 `T_1`=293 K , `T_2`=313 K `logK_2/K_1=-(E_a)/(2.303R)[1/T_1-1/T_2]` Thus, on calculating and substituting values, we GET : `E_a=52.86 KJ "MOL"^(-1)` |
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| 24688. |
The rate of a particular reaction quadruples when the temperature changes from 293K to 313 K. Calculate the energy of activation for such a reaction assuming that it does not change with temperature. |
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Answer» |
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| 24689. |
The rate of a particular reaction doubles when temperaturechanges from 27^(@) C to 37^(@)C. Calculate the energy of activation of such a reaction. |
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Answer» Solution :Here, we are given that When `T_(1)=27^(@)C=300" K, "k_(1)=k("say"). "When "T_(2)=37^(@)C=310" K",k_(2)=2k` Substituting these VALUES in the equation : `log""(k_(2))/(k_(1))=(E_(a))/(2.303R)((T_(2)-T_(1))/(T_(1)T_(2))),` we get, `log""(2k)/(k)=(E_(a))/(2.303xx8.314)XX(10)/(300xx310("J MOL"^(-1)))" or "log2=(E_(a))/(2.303xx8.314)xx(10)/(300xx310("J mol"^(-1)))` This on solving gives `E_(a)=53598.6" J mol"^(-1)=53.6" kJ mol"^(-1)` |
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| 24690. |
The rate of a heterogeneous reaction such as iron (solid) and any gas (oxygen) does not depend on |
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Answer» CONCENTRATION of reactants |
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| 24691. |
The rate of a gaseous reaction is given by the is expression k[A][B].If the volume of the reaction vessel is suddenly reduced to 1//4 of the initial volume, the reaction rate relating to original rate will be |
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Answer» `1//10` r=K[4A][4B]-16 k [A][B] i.e. 16 times. |
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| 24692. |
The rate of a gaseous reaction is given by the expression K[A][B]. If the volume of the reaction vessel is suddenly reduced to 1/4 th of the initial volume, the reaction rate relating to original rate will be |
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Answer» `1//10` |
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| 24693. |
The rate of a gaseous reaction is given by k[A] [B]. If the volume occupied by the reacting gases is suddenly reduced to half the original volume, the rate of the reaction relation relative to the initial rate will be |
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Answer» `1//8` On reducing the ORIGINAL volume to HALF , the concentration of reactants A and B will be doubled . LET the new rate be `r_(2)` . Then , `r_(2) =k [2]^(x) [ 2 B] ^(y) or r_(2) = k xx 4 [A]^(x) [B]^(y) ""... (ii)` or `r_(2) = 4 r_(1)`The rate will become four times relative to the initial rate . |
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| 24694. |
The rate of a gaseous reaction is halved when the volume of the vessel is doubled. What is the order of reaction ? |
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Answer» SOLUTION :Suppose, order of reaction is n and the reaction is A (G) `to`Products RATE=`k[A]^n`…(i) When volume is doubled, molar conc. becomes half and rate of reaction gets halved. `"Rate"/2=k(A/2)^n`…(ii) DIVIDING equation (i) by equation (ii), `(2)^1 =(2)^n` n=1 |
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| 24695. |
The rate of a gaseous reaction A + Bto C + D is equal to k [A][B]. The volume of the reaction vessel containing these gases is suddenly reduced to one-fourth of the initial volume . The rate of reaction would be |
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Answer» `1//16` When VOLUME of the vessel is REDUCED to one-fourth, concentrations become 4 times. Hence, NEW rate i.e. `"rate"_2= k[4A]^x[4B]^y` `:."rate"_2= 16 xx "rate"_1` |
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| 24696. |
The rate of a first order reaction : R rarr P is 7.5xx10^(-4) molL^(-1) "s"^(-1) . The rate concentration of R is 0.5 mol L^(-1) . The rate constant is : |
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Answer» `2.5xx10^(-5) s^(-1)` `(7.5xx10^(-4))/(60) mol L^(-1) s^(-1)` Rate = k[R] k = `("Rate")/([R])` `= (7.4xx10^(-4))/(60xx0.5)` `= 2.5 xx10^(-5)` |
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| 24697. |
The rate of a first-order reaction is 1.5xx10^(-2)"mol"L^(-1) at 0.5 M concentration of the reactant. The half-life of the reaction is |
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Answer» 0.383 min |
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| 24698. |
The rate of a first order reaction is 1.8xx10^(-3) "mol L"^(-1) when the initial concentration is 0.3 mol L^(-1) . The rate constant in the units of second is : |
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Answer» `1xx10^(-2) s^(-1)` `1.8 xx10^(-3) = k(0.3)` or `k=(1.8xx10^(-3))/(0.3)` `= 6xx10^(-3) min^(-1)` `=(6xx10^(-3))/(60)=1xx10^(-4)s^(-1)` |
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| 24699. |
The rate of a first order reaction is 1.5xx10^(-2) mol L^(-1) "min"^(-1) at 0.5 M concentration of the reactant . The half life of the reaction is : |
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Answer» `23.1 min` `k= ("Rate")/([C])` `=(1.5xx10^(-2))/(0.5) ` `3xx10^(-2)` `t_(1//2)= (0.693)/(3xx10^(-2))` = 23.1 min |
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| 24700. |
The rate of a first order reaction is 0.04mol L^(-1) sec^(-1) at 10 minute and 0.03mol L^(-1) at 20 minute after initiation. Find the half life of the reaction. |
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Answer» Solution :RATE `=K[A]` `0.04=k[A]_(10)` and `0.03=k[A]_(20)` `([A]_(10))/([A]_(20))=(0.04)/(0.03)=(4)/(3)` `t=(2.303)/(k)log.([A]_(10))/([A]_(20))` when `t=10^(1)`min. `10=(2.303)/(k)log.(4)/(3)` `k=(2.303)/(10)log.(4)/(3)=0.0288min^(-1)` `t_((1)/(2))=(0.693)/(k)=(0.693)/(0.0288)=24.06min`. |
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