Answer:
rate of recrystallization = 4.99 × 10⁻³ min⁻¹
Explanation:
For Avrami equation:
![y = 1-e ^{(-kt^n)} \\ \\ e^{(-kt^n)} = 1-y\\ \\ -kt^n = In(1-y) \\ \\ k = \dfrac{-In(1-y)}{t^n}](https://tex.z-dn.net/?f=y%20%3D%201-e%20%5E%7B%28-kt%5En%29%7D%20%5C%5C%20%5C%5C%20e%5E%7B%28-kt%5En%29%7D%20%3D%201-y%5C%5C%20%5C%5C%20-kt%5En%20%3D%20In%281-y%29%20%5C%5C%20%5C%5C%20k%20%3D%20%5Cdfrac%7B-In%281-y%29%7D%7Bt%5En%7D)
To calculate the value of k which is a dependent variable for the above equation ; we have:
![k = \dfrac{-In(1-0.40)}{200^{2.5}}](https://tex.z-dn.net/?f=k%20%3D%20%5Cdfrac%7B-In%281-0.40%29%7D%7B200%5E%7B2.5%7D%7D)
![k = 9.030 \times 10 ^{-7}](https://tex.z-dn.net/?f=k%20%3D%209.030%20%5Ctimes%2010%20%5E%7B-7%7D)
The time needed for 50% transformation can be determined as follows:
![y = 1-e ^{(-kt^n)} \\ \\ e^{(-kt^n)} = 1-y\\ \\ -kt^n = In(1-y) \\ \\ t =[ \dfrac{-In(1-y)}{k}]^{^{1/n}}](https://tex.z-dn.net/?f=y%20%3D%201-e%20%5E%7B%28-kt%5En%29%7D%20%5C%5C%20%5C%5C%20e%5E%7B%28-kt%5En%29%7D%20%3D%201-y%5C%5C%20%5C%5C%20-kt%5En%20%3D%20In%281-y%29%20%5C%5C%20%5C%5C%20t%20%3D%5B%20%5Cdfrac%7B-In%281-y%29%7D%7Bk%7D%5D%5E%7B%5E%7B1%2Fn%7D%7D)
![t_{0.5} =[ \dfrac{-In(1-0.4)}{9.030 \times 10^{-7}}]^{^{1/2.5}}](https://tex.z-dn.net/?f=t_%7B0.5%7D%20%3D%5B%20%5Cdfrac%7B-In%281-0.4%29%7D%7B9.030%20%5Ctimes%2010%5E%7B-7%7D%7D%5D%5E%7B%5E%7B1%2F2.5%7D%7D)
= 200.00183 min
The rate of reaction for Avrami equation is:
![rate = \dfrac{1}{t_{0.5}}](https://tex.z-dn.net/?f=rate%20%3D%20%5Cdfrac%7B1%7D%7Bt_%7B0.5%7D%7D)
![rate = \dfrac{1}{200.00183}](https://tex.z-dn.net/?f=rate%20%3D%20%5Cdfrac%7B1%7D%7B200.00183%7D)
rate = 0.00499 / min
rate of recrystallization = 4.99 × 10⁻³ min⁻¹
a typable representation of emotion
Theyre the big bunched up group in the middle of the periodic table
Answer:
Option 2 and 4 are correct
Explanation:
The reactants in the attached image have more enthalpy and hence less stability as they are more reactive. Thus, Product is more stable than the reactants.
This is an addition reaction in which two reactants add up to form the product.
Very less activation energy is required as the reactants themselves are unstable, possess high energy and hence are very reactive.
Reactants have more energy than the products.
Answer : The molecular weight of this compound is 891.10 g/mol
Explanation : Given,
Mass of compound = 12.70 g
Mass of ethanol = 216.5 g
Formula used :
![\Delta T_f=i\times K_f\times m\\\\T_f^o-T_f=i\times T_f\times\frac{\text{Mass of compound}\times 1000}{\text{Molar mass of compound}\times \text{Mass of ethanol}}](https://tex.z-dn.net/?f=%5CDelta%20T_f%3Di%5Ctimes%20K_f%5Ctimes%20m%5C%5C%5C%5CT_f%5Eo-T_f%3Di%5Ctimes%20T_f%5Ctimes%5Cfrac%7B%5Ctext%7BMass%20of%20compound%7D%5Ctimes%201000%7D%7B%5Ctext%7BMolar%20mass%20of%20compound%7D%5Ctimes%20%5Ctext%7BMass%20of%20ethanol%7D%7D)
where,
= change in freezing point
= temperature of pure ethanol = ![-117.300^oC](https://tex.z-dn.net/?f=-117.300%5EoC)
= temperature of solution = ![-117.431^oC](https://tex.z-dn.net/?f=-117.431%5EoC)
= freezing point constant of ethanol = ![1.99^oC/m](https://tex.z-dn.net/?f=1.99%5EoC%2Fm)
i = van't hoff factor = 1 (for non-electrolyte)
m = molality
Now put all the given values in this formula, we get
![(-117.300)-(-117.431)=1\times 1.99^oC/m\times \frac{12.70g\times 1000}{\text{Molar mass of compound}\times 216.5g}](https://tex.z-dn.net/?f=%28-117.300%29-%28-117.431%29%3D1%5Ctimes%201.99%5EoC%2Fm%5Ctimes%20%5Cfrac%7B12.70g%5Ctimes%201000%7D%7B%5Ctext%7BMolar%20mass%20of%20compound%7D%5Ctimes%20216.5g%7D)
![\text{Molar mass of compound}=891.10g/mol](https://tex.z-dn.net/?f=%5Ctext%7BMolar%20mass%20of%20compound%7D%3D891.10g%2Fmol)
Therefore, the molecular weight of this compound is 891.10 g/mol