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The reaction 2X \rightarrow B is a zeroth order reaction. If the initial concentration of X is 0.2 M , the half- life is 6 h. When the initial concentration of X is 0.5 M, the time required to reach its final concentration of 0.2 M will be :

  • Option 1)

    7.2 h

  • Option 2)

    9.0 h

  • Option 3)

    18.0 h

  • Option 4)

    12.0 h

Answers (2)

best_answer

 

Zero Order Reaction -

Zero order reaction means that the rate of the reaction is proportional to zeroth power of the concentration of reactants

 

- wherein

R\rightarrow P

Rate=\frac{-d(R)}{dt}=K[R]^{0}=K

t_\frac {1}{2}= time required for half completion of reaction=\frac{a}{2k}

 

 

 

Rate of Law = Dependence of Rate on Concentration -

The representation of rate of a reaction in terms of concentration of the reactants is known as Rate Law

or

The Rate Law is the expression in which reaction rate is given in terms of molar concentration of reactants with each term raised to some power, which may/maynot be equal to stoichiometric of the reacting species in a balanced chemical equation 

- wherein

Formula: aA+bB\rightarrow cC+dD

              Rate=\frac{dR}{dT}

              =\alpha [A]^{x}.[B]^{y}

             =k[A]^{x}.[B]^{y}

 K= rate constant

t_{\frac{1}{2}}=\frac{C_{0}}{2K}\Rightarrow 6=\frac{0.2}{2K}\Rightarrow k=\frac{1}{60}

Now, C_{t}=C_{o}-Rk

0.2=0.5-\frac{1}{60}\times t

0.3=\frac{t}{60}\Rightarrow t=18 hrs

 


Option 1)

7.2 h

Option 2)

9.0 h

Option 3)

18.0 h

Option 4)

12.0 h

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