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clear
//
//
//
//Variable declaration
dz1=4*10**-18 //diffusivity(m**2/s)
dz2=5*10**-13 //diffusivity(m**2/s)
T1=773 //temperature(K)
T2=1273 //temperature(K)
T3=573 //temperature(K)
T4=973 //temperature(K)
//Calculation
x1=(log(dz1))
y1=(log(dz2))
x2=(-1/(8.314*T1))
y2=(-1/(8.314*T2))
x=((x1-y1))
y=((x2-y2))
Q=x/y //activation energy(J/mol)
z=(y1-(y2*Q))
D0=exp(z) //diffusion coefficient(m**2/Vs)
D1=D0*exp(-Q/(8.314*T3)) //diffusivity at 300 C(m**2/s)
D2=D0*exp(-Q/(8.314*T4)) //diffusivity at 700 C(m**2/s)
//Result
printf("\n activation energy is %0.3f kJ/mol",Q/10**3)
printf("\n answer varies due to rounding off errors")
printf("\n diffusion coefficient is %0.3f *10**-4 m**2/s",D0*10**4)
printf("\n diffusivity at 300 C is %0.2f *10**-23 m**2/s",D1*10**23)
printf("\n diffusivity at 700 C is %0.3f *10**-15 m**2/s",D2*10**15)
printf("\n answer given in the book is wrong")
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