Separation of Mixtures and Solids

After gathering all the material needed to conduct these experiments, the first experiment was initiated. The mixture of solids was weighed out as well as the 10cm square piece of paper and the weighing dish. The mixture was spread out in a very thin layer on a piece of paper, the magnet was wrapped with clear plastic and the magnet was passed over the mixture several times to remove the iron from the mixture.

The iron was placed on the 10cm square paper and weighed. The next step was to separate out the sand. The sand was placed in the beaker with 50mL of water and heated to close to boiling. The hot liquid was poured into a Styrofoam cup and another 10mL of distilled water was added to the beaker and again it was heated to near boiling and poured into the same Styrofoam cup. The second heating was to ensure all the sodium chloride and benzoic acid was removed from the sand.

The Styrofoam cup was placed into an ice bath, the benzoic acid began crystallizing in the ice bath as it started cooling. The sand in the beaker was heated very carefully to allow it to dry. After the sand was dried it was weighed. The benzoic acid and salt were separated. A filter paper was inserted in the funnel and the cup with the salt and benzoic acid was poured into the funnel. A graduated cylinder with 5mL of water was inserted into the ice bath; this was poured into the funnel to eliminate any of the sodium chloride that may have been missed.

The filter paper was laid out on several paper towels to dry. After the filter paper has dried it will be weighed and the weight of the filter paper will be subtracted from the total to obtain the exact amount of the benzoic acid. The paper cup of sodium chloride was set aside to allow it to dry. Once it is dry it will be weighed and the weight of the paper cup will be subtracted to obtain the weight of the sodium chloride.

GramsPercent of MixtureTotals

Sand5.4g54%54%
Iron0.9g9%63%
Dried Sand1.2g12%75%
Salt1.8g18%93%
Benzoic Acid0.7g7%100%

Discussion

I can see room for error when pouring the water out of the beaker some of the sand could be poured out with it, thereby creating an inaccurate result of dried sand. There is also the possibility of some of the benzoic acid and sodium chloride remaining in the beaker, getting stuck to the sides and again creating an inaccurate result for these two mixtures. When the water is poured through the paper in the funnel some of the benzoic acid could remain in the sodium chloride which would create another inaccurate amount for the benzoic acid.

The iron could be slightly inaccurate due to the fact that it was not possible to get every single piece off the plastic wrap and into the dish, although the very small pieces may not have added up to much it might have contributed to an inaccurate amount. The initial sand weight is the most accurate; there was no room for error there.

Questions

1.How did your proposed procedures or flow charts at the beginning of this experiment compare to the actual procedures of this lab exercise? I knew the iron could be removed with a magnet. I wasn’t sure how to remove the sodium chloride and benzoic acid. 2.Discuss potential advantaged or disadvantaged of your proposed procedure compared to the one actually used. The only advantage to my procedure was using the magnet to remove the iron. I didn’t know how to remove the sodium chloride or benzoic acid. 3.How would you explain a sand recovery percentage that is higher than the original sand percentage?

Perhaps you didn’t remove all the iron out or there was still some sodium chloride or benzoic acid still left in the sand. 4.What were potential sources of error in this experiment? When pouring water out of the beaker some of the sand could be poured out with it. There is also the possibility of some of the benzoic acid and sodium chloride remaining in the beaker, getting stuck to the sides and again creating an inaccurate result for these two mixtures.

When the water is poured through the paper in the funnel some of the benzoic acid could remain in the sodium chloride which would create another inaccurate amount for the benzoic acid. The iron could be slightly inaccurate due to the fact that it was not possible to get every single piece off the plastic wrap and into the dish, although the very small pieces may not have added up to much it might have contributed to an inaccurate amount.