Q55 of 66 Page 57

Match the items of Column I and Column II.

Column I Column II


(i) Diamond (a) short interval of time


(ii) Instantaneous rate (b) ordinarily rate of conversion is


Imperceptible


(iii) Average rate (c) long duration of time


(i)(b),(ii)(a),(iii)(c)


(i) (b) Thermodynamics states that the diamond will convert to graphite. Since the Gibbs free energy of graphite is less than that of the diamond.


The rate of conversion of diamond to graphite is so slow that the change is not perceptible at all.


(ii) (a) Instantaneous means for an instant or short period of time.


Thus, the instantaneous rate is the slope concentration of reactant vs time graph i.e. - (d[R])/dt.


(iii) (c) The average rate of a reaction is the rate of appearance or disappearance of product or reactant respectively.


The time interval is large to get the large value of change in concentration of product or a reactant.


Rate_avg=-∆R/∆T=∆P/∆T


Where ∆R is the change in the molar concentration of a reactant, ∆P is the change in the molar concentration of product and ∆T is the time interval.


More from this chapter

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53

Note: In the following questions match the items of Column I with appropriate item given in Column II.

Match the graph given in Column I with the order of reaction given in Column II. More than one item in Column I may link to the same item of Column II.


Column I Column II


(i)


(ii) (a) first order


(iii) (b) zero order


(iv)


54

Match the statements given in Column I and Column II

Column I Column II


(i) Catalyst alters the rate of reaction (a) cannot be fraction or zero


(ii) Molecularity (b) proper orientation is not there


Always


(iii) Second half life of first order reaction (c) by lowering the activation


Energy


(iv) e–Ea/R T (d) is same as the first


(v) Energetically favourable reactions are sometimes slow (e) total probability is one


(vi) Area under the Maxwell Boltzman curve is constant (f) refers to the fraction of molecules with energy equal


to or greater than activation


energy


56

Match the items of Column I and Column II.

Column I Column II


(i) Mathematical expression for rate of reaction (a) rate constant


(ii) Rate of reaction for zero order reaction is equal to (b) rate law


(iii) Units of rate constant for zero order reaction is same as that of (c) order of slowest step


(iv) Order of a complex reaction is determined by (d) rate of a reaction


57

Note: In the following questions a statement of assertion followed by a statement of reason is given. Choose the correct answer out of the following choices.

Assertion : Order of the reaction can be zero or fractional.


Reason : We cannot determine order from balanced chemical equation