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More than likely, your seeing a chemical reaction. The bubbles that are forming are caused by two compounds interacting with each other.
In an aqueous solution that has not reached the saturation, the ions do not bond to create mineral crystals the motion of the ions that are dissolved would keep them from bonding. The ions creates temporary bonds to the partial charge present in the water molecules which will not allow for the ions to form a compound.
Answer : The time taken by the reaction is 
Explanation :
The expression used for second order kinetics is:
![kt=\frac{1}{[A_t]}-\frac{1}{[A_o]}](https://tex.z-dn.net/?f=kt%3D%5Cfrac%7B1%7D%7B%5BA_t%5D%7D-%5Cfrac%7B1%7D%7B%5BA_o%5D%7D)
where,
k = rate constant = 
t = time = ?
![[A_t]](https://tex.z-dn.net/?f=%5BA_t%5D)
= final concentration = 0.40 M
![[A_o]](https://tex.z-dn.net/?f=%5BA_o%5D)
= initial concentration = 2.16 M
Now put all the given values in the above expression, we get:
Therefore, the time taken by the reaction is
<span>Part A:
Molar mass luminol = 177g/mol
10g = 10/177 = 0.0565 mol Luminol
Dissolved in 75mL solution = 0.075L
Molarity = 0.0565/0.075 = 0.753M solution
Part B.
There should be no problem with this part If .0L contains 3.0*10^-2 mol Luminol, then 2.0L will contain 2*3.0*10^-2 = 6.0*10^-2 mol
Part C:
Use equation:
M1V1 = M2V2
0.753 *V1 = (3.0*10^-2) * 1000
V1 = 30/0.753
V1 = 39.8 mL of stock solution contains 3.0*10^-2 mol Luminol.</span>
