1. Do you believe your recrystallized acetylsalicyloc acid to be very pure? expl

Question

1. Do you believe your recrystallized acetylsalicyloc acid to be very pure? explain.
2. The solubility of benzoic acid in water is 68 g per 1 L at 95 degrees C and 1.7 g per 1 L at 0 degrees C. What is the minimum amount of water needed to recrystallize a 9.68 g sample of benzoic acid? How many grams of benzoic acid will be collected after crystallization is complete? How many grams of benzoic acid will remain in solution after the crystals are collected? (Show your work!)
3. Why was 50 mL of cold water added to the ethanol solution during recrystallization procedure?

Explanation / Answer

1.

Check the melting point of the recrystallised sample. If the melting point is matching with the theorectical value , the compound ( recrystallised acetylsalicylic acid ) is pure .

2.

Solubility of benzoic acid at 95 degrees = 68 g per 1 litre

Solubility at 0 degrees = 1.7 g / liter

Water required to recrystallise 9.68 g sample

We have 68 g dissolve in 1000 ml

9.68 g = ?

? = 9.68 x 1000 / 68 = 142.35 ml

Thus 9.68 g dissolves in 142.35 ml of water

At 0 degree solubility = 1.7 g in 1000 ml

Solubility in 142.35 ml = ?

? = 142.35 x 1.7 /1000 = 0.24 g

So weight of compound crystallized out = 9.68g – 0.24 g = 9.44 g

0.24 g remain in solution

3.

By adding cold water crystals will form. Aspirin is slightly soluble in water. In cold water solubility is less.

Related Questions

Navigate

• Browse (All)
• Browse 1
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.