1 files changed, 12 insertions, 8 deletions
diff --git a/3428/CH21/EX14.21.13/Ex14_21_13.sce b/3428/CH21/EX14.21.13/Ex14_21_13.sce
index 2da8e03a3..828158df5 100644
--- a/3428/CH21/EX14.21.13/Ex14_21_13.sce
+++ b/3428/CH21/EX14.21.13/Ex14_21_13.sce
@@ -1,18 +1,22 @@
 //Section-14,Example-1,Page no.-PC.21
 //To calculate collision number,collision frequency and mean free path for oxygen at 298K and 1 atm pressure.
 clc;
-M=((32*10^-3)/(6.023*10^23))
+M_w=32*10^-3                  //(kg/mol) molecular weight of oxygen
+N_A=6.023*10^23              //  Avogadro no.(mol^-1)
+M=((M_w)/(N_A))
 disp(M,'Mass of one oxygen molecule(kg)')
 //N=P/(R*T)
-N=(1*6.023*10^23*10^3)/(0.0821*298)
+P=1          //atm
+R=0.0821                //litreatmK^-1mol^-1
+T=298              //K
+N=(P*N_A*10^3)/(R*T)
 disp(N,'No.of O_2 molecules per m^3')
-R=8.314
-T=298
-m=32*10^-3
-v_avg=sqrt((8*R*T)/(%pi*m))
+R_1=8.314                      //kgm^2K^-1mol^-1
+m=32*10^-3                    //kgmol^-1
+v_avg=sqrt((8*R_1*T)/(%pi*m))           //ms^-1
 disp(v_avg,'Average velocity of O2 molecule(ms^-1)')
-sig=3.6*10^-10
-Z_1=sqrt(2)*pi*(sig)^2*v_avg*N
+sig=3.6*10^-10              //m
+Z_1=sqrt(2)*%pi*(sig)^2*v_avg*N 
 disp(Z_1,'Collision number(collisions per sec)')
 Z_11=(1/2)*(Z_1*N)
 disp(Z_11,'Collision frequency(collisions s^-1 m^-3)')