Separation of Mixture
Abstract
By separating chemicals out of a mixture and purifying them through sublimation and recrystiliation, changes in the substances physical properties can be shown. A salicylic acid-naphthalene mixture was mixed together with diethyl ether and saturated sodium bicarbonate. Two layers separated and were extracted after acidifying with HCl. This precipitated the crude salicylic acid. The left over mixture was combined with water and the two layers separated where crude naphthalene was recovered. Sublimation was used to purify the naphthalene. Sublimation is the process when a solid evaporates from a warm surface and condenses as a solid on a cold surface. The crude naphthalene had a melting point range of 85°-90° C while the 35.4% yield of pure naphthalene had a melting point range of 70°-76° C. Recrystallization was used to purify the salicylic acid. Recrystallization is the process of dissolving the original solid in a hot solvent and then allowing the solution to cool to let the solid crystallize again. The crude salicylic acid had a melting point range of 150°-153° C while the pure salicylic acid had a melting point range of 155°-158° C. (Percent yield not calculated for salicylic acid due to spill, new salicylic acid was provided by TA).
Percent Yield of Naphthalene: e35.4%=100% x (.062g pure naphthalene)/(.175g crude naphthalene)
Conclusion
The pure naphthalene melting point of 70°-76° C was lower than the crude naphthalene melting point of 85°-90° C showing that physical properties of this substance can change when in a mixture compared to being pure, in this case resulting in a lower melting point for the pure naphthalene. The pure salicylic acid melting point of 155°-158° C is higher than the crude salicylic acid melting point of 150°-153° C showing that physical properties of this substance can change when in a mixture compared to being pure, in this case resulting in a higher melting point for the pure salicylic acid.
By separating chemicals out of a mixture and purifying them through sublimation and recrystiliation, changes in the substances physical properties can be shown. A salicylic acid-naphthalene mixture was mixed together with diethyl ether and saturated sodium bicarbonate. Two layers separated and were extracted after acidifying with HCl. This precipitated the crude salicylic acid. The left over mixture was combined with water and the two layers separated where crude naphthalene was recovered. Sublimation was used to purify the naphthalene. Sublimation is the process when a solid evaporates from a warm surface and condenses as a solid on a cold surface. The crude naphthalene had a melting point range of 85°-90° C while the 35.4% yield of pure naphthalene had a melting point range of 70°-76° C. Recrystallization was used to purify the salicylic acid. Recrystallization is the process of dissolving the original solid in a hot solvent and then allowing the solution to cool to let the solid crystallize again. The crude salicylic acid had a melting point range of 150°-153° C while the pure salicylic acid had a melting point range of 155°-158° C. (Percent yield not calculated for salicylic acid due to spill, new salicylic acid was provided by TA).
Percent Yield of Naphthalene: e35.4%=100% x (.062g pure naphthalene)/(.175g crude naphthalene)
Conclusion
The pure naphthalene melting point of 70°-76° C was lower than the crude naphthalene melting point of 85°-90° C showing that physical properties of this substance can change when in a mixture compared to being pure, in this case resulting in a lower melting point for the pure naphthalene. The pure salicylic acid melting point of 155°-158° C is higher than the crude salicylic acid melting point of 150°-153° C showing that physical properties of this substance can change when in a mixture compared to being pure, in this case resulting in a higher melting point for the pure salicylic acid.