Phthalic acid has a solubility of approximately 18g per 100

Phthalic acid has a solubility of approximately 18g per 100 mL of water at 100 degrees celcius and 0.54g per 100 mL of water at 15 degrees celsius.

A. Calculate the amount of hot solvent required to dissolve 1.0g of crude ophthalmic acid

B. A student performed a recrystallization of phthalic acid and used 35mL of water as solvent. Assuming no loss of solvent to evaporation, calculate the loss of product in the filtrate based on the solubility of phthalic acid.

Solution

A) 18g per 100 water is solubility as hot temperature

hence per 1g acid we need = ( 100 ml water / 18g acid) x ( 1g acid) = 5.6 ml

B) 35 ml water dissolves = ( 18g acid / 100ml water ) x 35 m water = 6.3g acid

at cold teperature acid soluble was = ( 0.54g acid / 100 ml water) x 35 ml water = 0.189 g

loss of product = amount which is dissolved at cold temperature = 0.189 g