Separation of the Components of A Ternary Mixture 9/14/2011
Introduction This lab was the separation of the components of a ternary mixture. The three objectives in this
lab were: 1. Learn the different separation techniques which include; sublimation, extraction, decantation, filtration and evaporation. 2. Separate three components in a mixture using the separation techniques learned. of each of the three components present in a mixture. 3. Determine the mass percentages of e
In order to separate the components of a ternary mixture, one must understand what a mixture is and the different separation techniques that can be used. Mixtures are defined as a physical
combinat ion of two or more pure substances. Separation techniques are used to separate components that are not chemically combined. Because only physically combined mixtures are being used in this experiment, the separation techniques described in this experiment are based on physical changes, rather than chemical changes. 5
separation techniques
1. Sublimation- Involves the heating of a solid that passes directly into a gaseous phase without transitioning into a liquid phase. The reverse process where a gas goes into the solid phase is called deposition or condensation.
2.
Evaporation-
Involves the heating of a mixture in order to separate a volatile liquid in
the form of a vapor, while the residual components remain dry. 3.
Extraction-
Involves using of a solvent that selectively dissolves only a single component
while the other components remain insoluble. 4.
Filtration-
Involves separating a liquid f rom a solid using a porous material such as filter
paper. The porous material allows the liquid to pass through it but not the solid. 5.
Decantation-
Involves the separat ion of a liquid f rom insoluble solid sediment by
caref ully ully pouring the liquid without disturbing the solid.
Mixtures can be classified by composition as either a: 1. Homogenous Mixture: a mixture classified by having a uniform composition and of its components in one phase. appearance throughout. This mixture can have all of i
2. Heterogeneous Mixture: a mixture classified by having a composition that varies f rom one region to another. These mixtures can have components in different phases.
In this experiment a mixture containing Naphthalene (CH), H), common table salt (NaCl), and sea sand (Si0) will be separated according to a separation scheme shown in Figure A.
The separation of this mixture consists of 3 main steps: 1. Sublimation of n of naphthalene. 2. Extraction of NaCl using water as a solvent. 3. Recovering of NaCl and sea sand by evaporating water.
FIGURE A
Mixture Separation Scheme Mixture: Naphthalene, NaCl , Sea Sand Heat in Fume Hood
Residue: NaCl, Sea Sand
Naphthalene Sublimes
Extract with HO
Filter
Solution:
Residue:
NaCl (aq)
Wet Sea Sand
Evaporate
Evaporate
HO
HO
NaCl(s)
Sea Sand
Procedure
A.
Preliminary
Steps
1. Obtain a sample of the mixture, record the unknown code number on the data sheet.
2. Obtain a wide mouth 250 ml Erlenmeyer f la lask (Figure 1) and caref ully ully weigh it to the nearest 0.01 g on the top loading scale (Figure 2) and record its mass on the data sheet. 3. Place about 2 g of the mixture into the Erlenmeyer f la lask and caref ully ully weigh it to the nearest 0.01 g with the top loading scale and record its mass on the data sheet.
4. Determine the mass of the mixture y subtract ing the mass of the empty Erlenmeyer f la lask f rom the mass of the Erlenmeyer f la lask containing the mixture
and record the calculat ed mass onto the data sheet. B.
Sublimation of Naphthalene *NOTE: The sublimation of naphthalene must be carried out in a f ume hood. 1. Set up a hotplate (Figure 3) in the f ume hood (Figure 4) and turn the hotplate on. 2. Place an evaporating dish (Figure 5) containing ice on top of the Erlenmeyer f la lask containing the mixture (Figure B-1). *Make sure that no water gets on the underside of the evaporating dish or inside the f la lask. 3. Place the sublimation assembly on the hotplate that is in the f ume hood. Soon you will notice a solid will start collecting on the underside of the evaporating dish. Continue heating for 15 minutes. 4. Caref ully ully remove the assembly f rom the hotplate. 5. Caref ully ully remove the evaporating dish f rom the Erlenmeyer f la lask and collect the solid by caref ully ully scraping it off with a spatula (Figure 6) into a separate
container. (this will be disposed of later) 6. Stir the contents of the Erlenmeyer f la lask with a glass rod (Figure 7). (REPEAT STEPS 3-5) 7. Combine all of the scrapped naphthalene f rom the underside of the evaporating of it into the correct labeled waste container. dish and dispose of i
8.
Allow the Erlenmeyer f la lask to cool down. Once it is cool weigh the Erlenmeyer f la lask with the remaining solid in it and record the mass onto the data sheet.
9. Calculat e the mass of the sublimed naphthalene by subtract ing the mass of the Erlenmeyer f la lask with the remaining solid f rom the mass of the Erlenmeyer f la lask
with the original mixture. Af ter calculations record the calculat ed mass onto the data sheet.
C. Separation of the water insoluble solid 1. Add 25 ml of distilled water to the solid in the Erlenmeyer f la lask. Heat and stir for 5 minutes. The NaCl should dissolve f ully ully in the water, while the sea sand remains insoluble. 2. Weigh a clean 150-ml beaker (Figure 8) with 2-3 boiling chips (Figure 9) to the nearest 0.01 g and record its mass onto the data sheet. of filter paper (Figure 10) according to the steps shown in figure C-1 3. Fold a piece of fi
4. Place the folded filter paper inside a f unnel (figure 11). The paper will need to be wetted with water, once wet adjust the filter paper so that it lies f lat lat on the walls of the f unnel.
5. Assemble the apparatus for gravity filtration (Figure 12) as it is shown in Figure C-2, placing a clean beaker (beaker 1) under the f unnel. 6. Pour the mixture contained in the Erlenmeyer f la lask into the gravity filtration apparatus and collect the filtrate into beaker 1 as shown in Figure C-3 *DO NOT DISCARD THE FILTER PAPER: the filter paper containing the wet sand needs to be set aside for part D.
7. Rinse the Erlenmeyer f la lask with 5 ml of water, pour over the residue in the f unnel. And add the liquid to the filtrate in beaker 1. * REPEAT THIS STEP ONCE
MORE. 8. Place beaker 1 on the hotplate and heat. As the amount of liquid reduces, the NaCl dissolved will start to precipitate as a white solid. When the liquid is f ully ully evaporated, allow the beaker to cool down to room temperature.
9. Weigh beaker 1 with the dry NaCl, and record the mass on the data sheet. 10. Determine the mass of the recovered NaCl by subtracting the mass of the empty beaker 1. Once calculations are done record the mass of the recovered NaCl on the data sheet. Figures of Steps B
Figure B-1
&C
Figure C-2
Figure C-1
D. Drying
the Sea Sand Sample for Reco very Calculations
1. Weigh a second clean 150-ml beaker (beaker 2) to the nearest 0.01 g and record its mass on the data sheet.
2. Transfer the wet sand f rom the filter paper to beaker 2. 3. Place beaker 2 with the wet sea sand on the hotplate and heat the sand to dryness. When the sand is completely dry, the sand should be f ree f lowing. 4. Allow the sand to cool to reoom temperature. Weigh the beaker containing the f ry ry sand to the nearest 0.01 g and record this mass onto the data sheet.
5. Determine the mass of the recovered sea sand by subtracting the mass of the empty beaker 2 f rom the mass of the beaker containing the dry sand. Record the mass of the recovered sand on the data sheet. E.
Calculations and Equations 1. Calculat e the percent yield using the following formula:
%
yield= (1.73g/1.76g)x100= 98.3 %
2. Calculat e the percentage of e of each component in the mixture using the following formula:
%
Naphthalene= (0.13g/1.76g)x100= 7.39 %
%NaCl= %Sea
(1.23g/1.76g)x100= 69.9 %
= 98.3% (% Yield)
sand= (0.37g/1.76g)x100= 21.0 %
Equipment Here are some pictures of the equipment used in this experiment: Figure 2
Figure 3
Figure 4
Figure 1
Figure 7 Figure 5 Figure 6
Figure 8 Figure 9 Figure 11
Figure 10
Figure 12
Unknown Code #:
Data and Calculations
588 Data Sheet
Separation of the components of a Ternary Mixture M ixture of Erlenmeyer f la 1. Mass of E lask 126.74 g of Erlenmeyer f la 2. Mass of E lask + Mixture 3. Mass of Mixture (2)-(1) of Erlenmeyer f la 4. Mass of E lask and solid af ter sublimation of naphthalene 5. Mass of n (2)-(4) 6. Mass of beaker 1
128.5 g 1.76 g 128.63 g 0.13 g 67.09 g
7. Mass of beaker 1 and NaCl
68.32 g
8. Mass of NaCl (7)-(6) 9. Mass of Beaker 2
1.23 g 66.36 g
10. Mass of beaker 2 and Sea sand
66.73 g
of sand 11. Mass of s (10)-(9)
0.37 g Calculations
12. Mass of recovered solids (5)+(8)+(11) 13. Percent Yield %=[(12)/(3)] x 100 of naphthalene 14. Percentage of n %=[(5)/(3)] x 100 15. Percentage of NaCl
1.73 g 98.3% 7.39% 69.9%
%=[(8)/(3) ]x 100 of Sea sand 16. Percentage of Se %=[(11)/(3)] x 100
21.0%
Results and Discussion In this lab certain separat ion techniques were used and learned. Sublimation of naphthalene was done in part B. First an empty Erlenmeyer f la lask was obtained and weighed. 2g of an unknown mixture was placed into the f la lask and weighed again. The mass of the mixture was obtained by subtract ing the weight of the empty Erlenmeyer f la lask f rom the Erlenmeyer f la lask
containing the mixture. The mass of the mixture was 1.76g according to calculat ions. Next an evaporating dish containing ice was put on top of an Erlenmeyer f la lask containing the unknown mixture. This assembly was placed on the hot plate in the f ume hood. It was noticed that a
white solid started collecting on the underside of the evaporating dish. Af ter heating for another 15 minutes the assembly was removed f rom the hotplate. Using a spatula the solid under t he evaporating dish was scraped off and put into a b eaker. Af ter t he solid was scraped off, the remaining solid in the Erlenmeyer f la lask was stirred w ith a glass rod. The assembly was heated a gain for 15 minutes and the solid u nder the dish was added to the beaker c ontaining
the previous solid that was scraped off. The contents of the beaker were disposed of in the labeled waste container. Af ter heating the Erlenmeyer f la lask for a second time it was set aside to cool down. Once it was completely cool, the Erlenmeyer f la lask with the remaining solid was weighed. The mass of the sublimed naphthalene was calculat ed by subtract ing the mass of the Erlenmeyer f la lask with the remaining solid f rom the mass of the Erlenmeyer f la lask with the original mixture. Af ter calculations the mass of the naphthalene came out to be 0.13 g. Part C extraction was observed in separation of the water insoluble solid. The Erlenmeyer f la lask f rom part B was used. 25 ml of distilled water was added to the solid in the Erlenmeyer f la lask, it wa s then heated w hile stirred occasionally for 5 minutes. The NaCl was said t o dissolve
leaving only t he insoluble sea sand in the f la lask with the water. Three boiling chips were added to a cl ean 150 ml b eaker a nd w ere weighed t o the nearest 0 .01 g. Filtration was also observed in this experiment, first filter paper was folded and wetted t hen placed f lat lat into a f unnel. The f unnel was placed into the apparatus for the gravity filtration. The beaker containing the boiling
chips was placed under the f unnel. The remaining mixture found in the Erlenmeyer f la lask was then poured into the gravity filtration apparatus and the filtrate was collected into the beaker with the boiling chips. Af ter that the f unnel was removed and an additional 5 ml of distilled water was put into the f la lask and poured over the residue found in the f unnel. The 5 ml of water
was poured twice over the f unnel. Af ter all of the residue and filtrate was filtered the beaker was placed on a hotplate, the water boiled for a few minutes and the amount of liquid reduced quickly. The NaCl that was dissolved started to precipitate into a white solid. Once all of the
liquid was gone the beaker was taken off the hotplate to be cooled to room temperature. Once ully cooled the weight of the beaker containing now dry NaCl wa s taken. The mass of the it was f ully recovered NaCl was determined by subtracting the mass of the empty b eaker a nd t he mass of the beaker containing the dry NaCl. According to calculat ions the mass of the recovered NaCl was measured at 1.23 g. In part D, the sea sand had t o be dried for the recovery calculations on the data sheet. To dry sea sand first the sand was placed into a clean 150 ml beaker and was weighed. The wet sand was then transferred f rom the filter paper into the clean beaker. The beaker containing
the sand was then placed onto the hot plate, until t he sand had dried completely. The sand was then cooled to room temperature and weighed to the nearest 0.01 g. The mass of the recovered sea sand was determined by subtracting the mass of the empty beaker f rom the mass of the beaker containing dry sea sand. The mass of the recovered sea sand was calculated
at 0.37 g. For t he Calculations part of the experiment percent yield a nd percentages of all substances was found. The percent yield was found by dividing the mass of the recovered solids by the mass of the mixture, then multiplying the answer by 100. (1.73/1.76)x100= 98.3%. The percentage yield for this experiment came out to be 98.3%. The makeup of that 98.3% is
divided up between naphthalene at 7.39%, NaCl at 69.9% and sea sand at 21.0%. Some errors that could ha ve been made in this experiment include: 1. Not measuring the 2 grams of unknown mixture in the beginning of the experiment. 2. Rushing through the experiment by not letting the sand f ully ully dry, not letting the naphthalene sublimate for 30 minutes, or not letting the NaCl dissolve in the water.
3. In the lab book it was stated not to let the water boil during the heating of the filtered water. In the lab though the water was allowed to be boiled, which may have disturbed the experiment.
4. Reasons why percentage yield may have differed f rom 100% could also be human error in calculations and t he mass of the recovered solids was less than the mixture
%. 5. If water got on the underside of the evaporating dish or inside the f la lask during naphthalene sublimation, it would affect the naphthalene f rom sublimating into a gas.
Post Lab Questions 1. What was your percent yield? The percent yield for this experiment was 98.3%. This was found by dividing the mass of the
recovered solids by the mass of the beginning mixture and multiplying by 100. (1.73g/1.76g)x100= 98.3% 2. Give two reasons why the percentage yield can differ from 100 %.
Do
not include in your
answer explanations like Human error or instrumental error. Two reasons why the percentage yield c ould differ f rom 100% include rushing and not letting
all of the NaCl dissolve or not l etting the naphthalene sublimate completely, and if the mass of the recovered solids was less than the mixture %. 3. If a student was unable to completely dissol ve 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 w ould be lower b ecause the mass of the NaCl would not have been f ully ully
calculat ed in the mass of recovered solids. When the NaCl precipitates into a white solid it would be a smaller amount thus affecting the percentage yield. 4. The sand was not completely free of water when the mass was reported on the data sheet. How does this affect the calculated percentage composition of the sand in the mixture? Would the calculated percentage composition of the sand be higher, lower, or unaffected? The percent c omposition would be higher b ecause the mass would be calculated higher in the sand. The water would weigh the sand down and y ou would not be taking the mass of the sand
you would be taking the mass of the sand plus the water in it.
