Tag: rate of chemical reaction

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Questions Related to rate of chemical reaction

Multiple choice chemistry rates of reaction introduction to rate of reaction rate of chemical reaction rate of reaction

Which of the following is (are) true for first order reaction?

  1. Rate of reaction is fastest at the beginning of reaction.

  2. Rate of reaction is fastest when (reactants)=(products)

  3. Rate of reaction increases with temperature

  4. Ea decreases considerably as temperature as temperature increases, hence the reaction becomes faster
Reveal answer Fill a bubble to check yourself
A,C Correct answer
Explanation

A] True. for first order reactions, products are formed at the fastest rate during the  beginning of the reaction.

B] False. When reactants>Products, the rate of reaction is fast.
C] True. Increasing the temperature increases the rate of reaction.
D] False. Activating energy does not decrease, but increasing the temperature allows crossing of energy barrier.

Multiple choice chemistry rates of reaction introduction to rate of reaction rate of chemical reaction rate of reaction

For the reaction $2A + B + C \rightarrow 2D$. The observed rate law is Rate=$K[A]{ [B] }^{ 2 }$. Correct statements are
a) An increase of cone .of C does not affect the rate
b)Doubling the conc of A doubles the rate
c)Tripling the conc of B increases the rate by 9 times
d)Doubling the conc of C, doubling the rate

  1. a,b,c

  2. b,c,d

  3. d

  4. c,d
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Given  rate is $k[A]{ [B] }^{ 2 }$

 It is overall ${ 3 }^{ rd }$ order  reaction with a following  first order  and B following second order.
 (a) True  C is not affecting the rate of reaction.
 (b) True $rate _{ 1 }\quad =k[A]{ [B] }^{ 2 }\ rate _{ 2 }\quad =k[2A]{ [B] }^{ 2 }=2k[A]{ [B] }^{ 2 }\ =2\times rate _{ 1 }$
 (c) True $rate _{ 1 }\quad =k[A]{ [B] }^{ 2 }\ rate _{ 3 }=k[A]{ [3B] }^{ 2 }=9Kk[A]{ [B] }^{ 2 }\ =9\times rate _{ 1 }$
(d)False C does not affected  the rate in any manner.

Multiple choice chemistry rates of reaction introduction to rate of reaction rate of chemical reaction rate of reaction

${ SO } _{ 2 }$ react with ${ O } _{ 2 }$ as follows :


 ${ 2SO } _{ 2 }+{ O } _{ 2 }\rightarrow { 2SO } _{ 3}$ 


The rate of disappearance of ${ SO } _{ 2 }$ is $2.4\times { 10 }^{ -4 }$ mol ${ lit }^{ -1 }{ min}^{ -1 }$, then :

  1. Rate of reaction is $1.2\times { 10 }^{ -4 }\quad mole{ lit }^{ -1\quad }{ min }^{ -1 }$
  2. Rate of appearance of ${ SO } _{ 3 }$ is $2.4\times { 10 }^{ -4 } { mole\quad lit }^{ -1 }min^{ -1 }$
  3. Rate of disappearance of ${ O } _{ 2 }$ is $1.2\times { 10 }^{ -4 } { mole\quad lit }^{ -1 }min^{ -1 }$
  4. Rate of reaction is twice the rate of disappearance of ${ SO } _{ 2 }$
Reveal answer Fill a bubble to check yourself
B,C,D Correct answer
Multiple choice chemistry rates of reaction introduction to rate of reaction rate of chemical reaction rate of reaction

Which of the fallowing can enhance the rate of the reaction ?

  1. increasing the temperature

  2. increasing the concentration of products

  3. increasing the activation energy

  4. using a +Ve catalyst
Reveal answer Fill a bubble to check yourself
A,D Correct answer
Explanation

Solution:- (A) increasing the temperature and (D) using a +ve catalyst
  • Temperature is a measure of the kinetic energy of a system, so higher temperature implies higher average kinetic energy of molecules and more collisions per unit time. Hence an increase in temperature is accompanied by an increase in the reaction rate. 
  • A higher concentration of reactants leads to more effective collisions per unit time, which leads to an increased reaction rate (except for zero order reactions). Similarly, a higher concentration of products tends to be associated with a lower reaction rate.
  • Catalysts (e.g., enzymes) lower the activation energy of a chemical reaction and increase the rate of a chemical reaction without being consumed in the process. 
  • Hence, using a positive catalyst and increasing the temperature, both can enhance the rate of reaction.

Multiple choice chemistry rates of reaction introduction to rate of reaction rate of chemical reaction rate of reaction

Rate of formation of $SO _{3}$ according to the reaction $2SO _{2}+O _{2} \rightarrow 2SO _{3}$ is $1.6 \times 10^{-3}\ kg\ min^{-1}$ Hence rate at which $SO _{2}$ reacts is :-

  1. $1.6 \times 10^{-3}\ kg\ min^{-1}$
  2. $8.0 \times 10^{-4}\ kg\ min^{-1}$
  3. $3.2 \times 10^{-3}\ kg\ min^{-1}$
  4. $1.28\times 10^{-3}\ kg\ min^{-1}$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

According to the balanced chemical equation 2SO2 + O2 -> 2SO3, the stoichiometric coefficients for SO2 and SO3 are both 2, meaning they react and form in a 1:1 molar ratio. Since their molar masses are different, we account for them: rate of SO2 consumption = rate of SO3 formation * (Molar Mass of SO2 / Molar Mass of SO3). Molar mass of SO2 is 64 g/mol and SO3 is 80 g/mol. Thus, rate = 1.6 * 10^-3 * (64 / 80) = 1.28 * 10^-3 kg min^-1.

Multiple choice chemistry rates of reaction introduction to rate of reaction rate of chemical reaction rate of reaction

$C _{4}H _{8}\rightarrow 2C _{2}H _{4}$; rate constant $=2.303\times 10^{4}\sec^{-1}$, After what time the molar ratio of $\dfrac{C _{2}H _{4}}{C _{4}H _{8}}$ attain the value $1$

  1. $176\ sec$
  2. $3522\ sec$
  3. $1661\ sec$
  4. $1761\ sec$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

For the reaction C4H8 -> 2C2H4, if the ratio [C2H4]/[C4H8] = 1, then [C2H4] = [C4H8]. Using the integrated rate law for a first-order reaction, we solve for t.

Multiple choice chemistry rates of reaction introduction to rate of reaction rate of chemical reaction rate of reaction

In which of the following cases, the reaction goes farthest to completion?

  1. $A \rightleftharpoons B (K = 10^3)$
  2. $P \rightleftharpoons Q (K = 10^{-2})$
  3. $A + B \rightleftharpoons C + D (K = 10)$
  4. $X + Y \rightleftharpoons XY _2 (K = 10^{-1})$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Higher the equilibrium constant, faster the rate of reaction

$A+B \rightleftharpoons C+D$
$\Rightarrow K=\cfrac {[C][D]}{[A][B]}$
To complete the reaction fastest the numerator of $RHS$ will be higher.
$\therefore$ Option A 
$A\rightleftharpoons B(K=10^3)$ is correct, because equilibrium constant in option A is higher than remaining options.

Multiple choice chemistry rates of reaction introduction to rate of reaction rate of chemical reaction rate of reaction

On increasing the pressure three fold, the rate of reaction of ${ 2H } _{ 2 }{ S }$ + ${ O } _{ 2 }$ $\rightarrow $ products would increase

  1. 3 times

  2. 9 times

  3. 12 times

  4. 27 times
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Rate$=$ ${K _{{p^2}}}{H _2}S \times P{O _2} = x$ $($rate$)$


On increasing the pressure three fold :


Rate$=$ $K{\left( {3{P _{{H _2}S}}} \right)^2}\left( {3P{O _2}} \right)$

$=$ $K \times 9{P^2} _{{H _2}S} \times 3P{O _2}$

$=$ $K \times 27 \times {P _{{H _2}S}} \times P{O _2} = 27$

the rate will increases $27$ times 

Hence, option $(D)$ is correct answer.