Apure organic amide product (2.85 g) which has a molecular weight of 285.34 g/mol was fully dissolved in 20ml of the boiling solvent, hexanes. this organic amide product then underwent a recrystallization when the solvent was cooled to 0° c. the recrystallized organic product (2.62 grams) was obtained after vacuum filtration. what is the solubility of the organic amide product in the solvent, hexanes, at 0° c?

The solubility of the organic amide product in the solvent hexane is 0.0403 moles/L at 0° C

Explanation:

When 2.85gm dissolved in 20ml of boiling solvent

After re crystallization 2.62gm was obtained

so, that the dissolved amount at 0° C is

2.85 - 2.62

= 0.23 gm in 20ml hexane

Mole of amide

Solubility

               = 0.0403 moles/L

Therefore, the solubility of the organic amide product in the solvent hexane is 0.0403 moles/L at 0° C

i believe you are right for all except the 3rd ( look at sqdancefan his answer is much better)

your answer is a. the enthalpy of formation for a pure element in its standard state is always positive.