(a) Explain the following terms : (i) Rate of a reaction. (ii) Activation energy of a reaction. (b) The decomposition of phosphine, PH_(3), proceeds according to the following equation : 4" PH"_(3)(g)to P_(4)(g)+6" H"_(2)(g) It is found that the reaction follows the following rate equation : Rate =k[PH_(3)] The half-life of PH_(3) is 37.9 s at 120^(@)C. (i) How much time is required for 3//4th of PH_(3) to decompose. (ii) What fractional of the original sample of PH_(3) remains behind after 1 minute ?

(a) Explain the following terms : (i) Rate of a reaction. (ii) Activat

1.	(a) Explain the following terms : (i) Rate of a reaction. (ii) Activation energy of a reaction. (b) The decomposition of phosphine, PH_(3), proceeds according to the following equation : 4" PH"_(3)(g)to P_(4)(g)+6" H"_(2)(g) It is found that the reaction follows the following rate equation : Rate =k[PH_(3)] The half-life of PH_(3) is 37.9 s at 120^(@)C. (i) How much time is required for 3//4th of PH_(3) to decompose. (ii) What fractional of the original sample of PH_(3) remains behind after 1 minute ?
Answer» SOLUTION :`"[""(b) (i) "t=(2.303)/(0.693//t_(1//2))LOG""(a)/(a-(3)/(4)a)=75.82" s"` (ii) `log""([A]_(0)) /([A])=(kt)/(2.303)=((0.693//37.9)(60))/(2.303)=0.4763` `[A]_(0)//[A]="Antilog "0.4763=1.2994" or "[A]//[A]_(0)=1//1.2994=0.77=77%"]"`