United Arab Emirates UniversityDepartment of Chemistry

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Experiment No : 1 Experiment Name : Separation of components of a mixture

Name Amna Saif Alfalahi

ID201307954

SECTION54

Date:

Objective:To become familiar with the methods of Separating substance from one anther using decantationFiltration sublimation and evaporation techniques .

Theory:

There are several ways to separate substances, depending on the properties of the substances. Some substances dissolve when placed in water. These substances are miscible or soluble in water. Others are unchanged when placed in water. These substances are immiscible or insoluble in water. Thus, if a soluble substance is mixed with an insoluble substance, separation through decantation can take place. Decantation involves pouring water onto a mixture and stirring. The soluble substance will dissolve, leaving the insoluble one intact. The newly-formed aqueous mixture of water and the soluble substance can be poured into a separate container and heated so that the water evaporates. The substance have now been separated without any changes to the elemental composition of the substances. Decantation is usually performed more than once on the insoluble substance to ensure that all particles of the soluble substance have been removed.Some substances can pass directly from the solid to the gaseous stage without first melting and becoming liquid. These substances are said to be able to sublime. Substances that sublime, when mixed with substances that do not sublime, can be separated by heating the mixture until the substance that can sublime is completely gone. One can determine whether sublimation is complete by whether smoke is being produced. If smoke is being produced, then sublimation is occurring.A third method of separation is called filtration. This is the process of separating a solid from a liquid by means of a porous filter which allows the liquid to pass through but not the solid. This has nothing to do with solubility or ability to sublime, but rather simply the physical phase of the substances and the permeability of the filter.Antoine Lavoisiers Law of the Conservation of Mass states that in a chemical reaction, matter is neither created nor destroyed. Likewise, in any physical separation, matter is not created or destroyed. The mass of the products of separation should equal the mass of the original substance.All ionic compounds are soluble in water. Some common substances that can sublime are naphthalene and ammonium chloride. In this experiment, three pre-mixed substances will be separated using the methods outlined above. These substances are sodium chloride (an ionic compound, soluble in water), ammonium chloride (able to sublime), and silicon dioxide (insoluble in water, not able to sublime).

EXPERIMENTAL:

1. Apparatus:Blance , Bunsen , burner and hose , tongs evaporation dish (2) , watch glass, 500\100 ml graduated , cilynder , clay triangles (2) or wire gauze (2) ring stands (2) , iron rings (2), glass stirring rods

2. Reagent: Mixture of Ammonium Chloride (NH4Cl)Sodium Chloride (NaCl)3.Sand (SiO2) .

3. Procedure:A) . Sublimation of ammonium chloride (NH4Cl):1) Accurately weigh 3.00xx gm ( Record in your report sheet) ofsample (mixture) to a clean dry evaporating dish-1.

2) Weigh evaporating dish and sample together and record the same.

3) Heat the sample until all the NH4Cl sublime, Allow dish to cool andrecord its mass accurately.

B) . Extraction of NaCl1) Weigh a second clean, dry evaporating dish-2

2) Add 7ml DI water to the dish-1 and stir well to dissolve NaCl andset aside 5minute to settle down sand.

3) Decant the liquid carefully to the second dish-2.

4) Gently heat dish-2 until all water evaporate out. Allow the dish tocool and records its mass. C). Drying SiO2

1) Slowly heat dish-1 until sand appears dry. Allow the dish to cooland record its mass.

4. Calculations & Result:

A) Sublimation of ammonium chloride (NH4Cl):1. mass of sample = 3.06 g.2. mass of sample + evaporating dish -1= 48.0039g.3. mass of evaporating dish-1 = 44.9439 g.4. mass after sublimation of NH4Cl = 47.469 g.5. mass of NH4Cl = 0.5349 g.6. percentage of NH4Cl =17.48 %B) Extraction of NaCl1. mass of evaporating dish-2 = 101.626g.2. mass after evaporation = 102.639g.3. mass of NaCl : 1.013g.4. percentage of NaCl = 33.1%C) Drying SiO 1. mass after evaporating SiO2 =46.356 g.2. mass of evaporating dish-1 = 44.9439 g.3. mass of SiO2 =1.4121g.4. percentage of SiO2 = 46.1%D) Mass of original sample =3.06g.Mass obtained =2.96g.Percentage of error =3.29%

5. Conclusion:The experiment was completed to a high degree of success. Familiarity with the methods of separating substances from one another using decantation, extraction, and sublimation techniques was gained, and the material was recovered to a reasonable degree of accuracy

POST LAB QUESTIONS: Experiment 11. What was your percent yield?2.96\3.06 *100=96.73

2. Give two reasons why the percentage yield can differ from 100%. Do not include in your answer like human error or instrumental error.

Rushing and not letting the NaCl dissolve completely or if the mass of the recovered solids was less than the mixture%. Another reason would be if the water boiled too much and boiled over, NaCl may have been lost. This would greatly affect this experiment

3. If a student was unable to completely dissolve all the NaCl in the water, what effect would this have on the calculation of the percentage yield? Would the percentage yield be higher, lower or unaffected?

The percentage yield would belower because the mass of the NaCl would not have been fully calculated in the mass of recovered solids.When the NaCl precipitates into a white solid i twould be a smaller amount thus affecting the percentage yield

UAEU/COS/CHEM-115/SPRING-2016