Ibuprofen is a carboxylic acid. It will react with the NaOH to for the sodium salt of the carboxylic acid. The salt is typically soluble in water. X-COOH + NaOH = X-COO-Na+ + H2O So it will dissolve in a strongly alkaline solution and precipitate out when you add acid (the reaction in reverse). Solution Ibuprofen is a carboxylic acid. It will react with the NaOH to for the sodium salt of the carboxylic acid. The salt is typically soluble in water. X-COOH + NaOH = X-COO-Na+ + H2O So it will dissolve in a strongly alkaline solution and precipitate out when you add acid (the reaction in reverse)..