Please explain in detail Sulfanilamide has the following ethanol solubility at 7
ID: 883509 • Letter: P
Question
Please explain in detail
Sulfanilamide has the following ethanol solubility at 7W C: 210 mg/m1 and 14 mg/ml at 0 degree C . (a) Calculate the minimum amount of ethanol require to dissolve 15 g of sulfanilamide in 78 degree C ethanol. (b) Is this the amount of solvent you would initially add to the solid, to start the crystallization? (c) If you cool the solution with the minimal amount of solvent you calculated above down to 0 degree C, how much Sulfanilamide will remain dissolved in the mother liquor?Explanation / Answer
Ok, first you must remember that the solubility of a substance is influenced by the temperature generally as follows:
At higher temperatures, increased solubility and vice versa.
This is because with increased temperature molecules movement become more and more energetic, resulting in a greater amount of movement in the solution. An example of this in when put sugar in milk, in hot milk the sugar dissolves quickly, in cold milk this process requires that you mix it.
Now back to your exercise we have the following:
a) Is a rule of three: (we have to change g in mg: 1,5 g=1500mg)
requires
210 mg of sulfanilamide ------------------------------1 ml og ethanol (at 78°C)
1500mg of sulfanilamide ------------------------------- X ml
X= 4.14 ml of ethanol
b) Crystallization is the process of formation of solid crystals precipitating from a solution, the solution has to contain more solute entities dissolved than it would contain under the equilibrium for this to happen.
So we calculate the exact concentration which does not crystallize, if we add more solvent it will dissolve, this means that crystallizes less, so if we want the solute concentration higher (which is what we need to crystallize) we need to add less than 4.14 ml ethanol. So the answer is NO.
c) same as the first:
14 mg of sulfanilamide ------------------------------- 1 ml of ethanol (at 0°C)
X mg of sulfanilamide --------------------------------- 4.14 ml (mother liquor)
X= 57.96 mg of sulfanilamide, only this will remain dissolved