Post Lab Number Two Separation of a Mixture PDF

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Nhi Chung General Chemistry I - Chem 1411, HCC Alief Campus October 11, 2017

Post Lab n. Two; two extra points for wearing a lab coat and providing the group's data on the board, even though my group and I failed to provide the correct data.

Separation of a Mixture

INTRODUCTION The purpose of this lab is to know how to separate and calculate the percentage of the composition of a mixture. Depending on the components, it is important to know the differences in physical properties when separating them by specific materials for the mixtures such as stirring rod. Furthermore, chemicals such as sand, sodium chloride (NaCl), ammonium chloride (NH4CL), and unknown or "super mixture" are the main focus of this experiment. Thus, this experiment is about collecting, finding, calculating the data for these component mixture's grams by using either the balance or digital scales.

EXPERIMENTAL In order to weigh and record data from the unknown or "super mixture", get a clean, small evaporating dish that weighs almost to 0.01 g and carefully measure 2.00 g of the unknown or "super mixture" in the evaporating dish. After that, use a glass stirring rod to stir the super mixture while using the lab's heater, which takes about ten to fifth-teen minutes. Once ten to

fifth-teen minutes has passed, a white, smoky vapor should appear, then place the super mixture on a wire gauze and glass to allow it to cool down that way; it would not burn the table. When finding the mass of ammonium chloride and calculating the percentage of NH4CL, use this formula: % NH4CL = (grams of NH4CL/ total grams of mixture) x 100. For a sand and NaCl, put them in a clean, small evaporating dish, add about 30 mL of water, heat and stir about five minutes. More importantly, weigh a second, large evaporating dish and watch glass until it is 0.01 g, then record the data on the lab report sheet. As for SiO2, find its mass and percentage by using this formula: % SiO2 = (grams of SiO2/ total grams of mixture) x 100. After that, heat the large evaporating dish that contains the salt water until the water has evaporated. Moreover, find and calculate the percentage of NaCl by using this formula: % NaCl = (grams of NaCl/ total grams of mixture) x 100. Most importantly, the total percentage of all of the three components must be calculated by using this formula: total mass recovered = grams of NH4Cl + grams of SiO2 + grams of NaCl and percent recovery = total grams of recovered mixture/ total grams of original mixture) x 100; therefore, the percentage should not be more or less than one hundred percent.

DATA Table 1: Part I (1) Mass of empty small evaporating dish

44.09 g

(2) Mass of small evaporating dish +

46.41g

mixture (3) Mass of mixture

2.32 g

Table 2: Part II (4) Mass of small evaporating dish + sand +

45.96 g

salt (5) Mass of ammonium chloride [(2) - (4)]

0.45 g

(6) Percentage of NH_4Cl = [(5)/ (3)] x 100

19.4 %

% NH4Cl = (grams of NH4Cl/ total grams of mixture) x 100 = (0.45g/ 2.32g) x 100 = 19.4% Table 3: Part III (7) Mass of small evaporating dish + dry

45.27g

sand (8) Mass of sand [(7) - (1)]

1.18g

(9) Percentage of SiO_2 = [(8)/ (3)] x 100

50.9%

% SiO2 = (grams of SiO2/ total grams of mixture) x 100 = (1.18g/ 2.32g) x 100 = 50.9% Table 4: Part IV (10) Mass of empty large evaporating dish + watch glass

99.42g

(11) Mass of large evaporation dish + watch glass + dry salt 100.11g

(12) Mass of dry salt [(11) - (10)]

0.69g

(13) Percentage of NaCl = [(12)/ (3)] x 100

29.8%

% NaCl = (grams of NaCl/ total grams of mixture) x 100 = (0.69g/ 2.32g) x 100 = 29.8% Table 5: Part V (14) Total mass(g) recovered = (5) + (8) + (12)

2.32g

(15) Percentage of mixture recovered = [(14)/ (3)] x

100%

10

Total mass recovered = grams of NH4Cl + grams of SiO2 + grams of NaCl = 0.45g + 1.18g + 0.69g = 2.32g Percent Recovery = (total grams of recovered mixture/ total grams of original mixture) x 100 = (2.32g/ 2.32g) x 100 = 100%

RESULTS AND DISCUSSION The concepts of this experiment are to determine whether or not the components have changed or remained the same during the procedures. In other words, the experiment is there to find and calculate the super mixture's gams during the physical process. When mixing the components in the hot plates and filling it with water, some of them have disappeared. However, sand has remained the same, even though different methods of physical properties were done. Furthermore, maybe these three-component's mass have increased when stirring and filling them with water, which is something to consider during this experiment. The separation of a mixture is done by considering the different physical properties of the components. Ammonium chloride is the only compound which is volatile; thus, the first step consists of warming up 2.32 g of the mixture. NaCl is soluble in water, so some water is added to

the remaining mixture and separated by decantation. The NaCl will be removed with the water and the mass can be determined by weighing the evaporating dish with a watch glass before and after evaporating the solution. The only component left in the mixture is sand, which not volatile nor soluble in water.

POST LAB QUESTIONS 1. A. Filtration separates an insoluble solid from a liquid by a simple process of going through the mixture with a porous material. B. Distillation separates two or more liquid components in a liquid mixture, which highly depends on their boiling points. C. Solubility is the total amount of the substance that dissolves into a solvent at a specific temperature. 2. Having some NaCl splattered out of the evaporating dish would affect the calculated percentage of mixture recovered upon separation by not having enough nor accurate total percent recovery. In addition, this would also affect the percentage of NaCl, which would ruin the entire procedure. 3. Mixture is done by the process of decantation, distillation, extraction, and chromatography, which are based on the physical properties. Whereas a pure substance does not depend on these physical changes. 4. This student made an error because the total percentage of these three compositions cannot be more or less than one hundred percent....