The answer would look something like this. (sorry for the ugliest diagram ever.)
The difference between a chemical change and a physical change lies in how the change affects the composition a substance. A chemical change occurs on the molecular level and produces a new substance. However, a physical change rearranges molecules and does not produce a new substance.
Answer:
volatility means liability to change rapidly and unpredictably, especially for the worse
MgSO₄•8H₂O
Magnesium sulfate octahydrate
<h3>Further explanation</h3>
Given
7.820 g of Magnesium sulfate (MgSO₄ • xH₂O)
3.547 g of anhydrous magnesium sulfate
Required
The formula
Solution
Mass of H₂O :
= 7.820 g - 3.547 g
= 4.273 g
MW MgSO₄=120 g/mol
MW H₂O = 18 g/mol
Mol ratio MgSO₄ : H₂O
= 3.547/120 g/mol : 4.273/18
= 0.0295 : 0.2374
= 1 : 8
The formula :
MgSO₄•8H₂O
Magnesium sulfate octahydrate
The 
value of HEPES is 7.5 and it is a weak acid. Now, the value of 
is calculated by below formula:
=
= 
Now, calculate 
:
As it is given that HEPES in the basic form having concentration 
. The hydroxide ion concentration is calculated by below formula for weak base:
![[OH^{-}] =\sqrt{k^{b}\times c}](https://tex.z-dn.net/?f=%5BOH%5E%7B-%7D%5D%20%3D%5Csqrt%7Bk%5E%7Bb%7D%5Ctimes%20c%7D)
Substitute the value of 
and c in above formula:
![[OH^{-}] =\sqrt{3.16\times 10^{-7}\times 0.1 M}](https://tex.z-dn.net/?f=%5BOH%5E%7B-%7D%5D%20%3D%5Csqrt%7B3.16%5Ctimes%2010%5E%7B-7%7D%5Ctimes%200.1%20M%7D)
= 
Now, calculate the value of 
from the above value.
![pOH = -log[OH]](https://tex.z-dn.net/?f=pOH%20%3D%20-log%5BOH%5D)
Put the concentration of 
in above formula:
= 
In last step, calculate the 
:
Substitute the value of
= 
Thus, the value of =
