Lab 2 Separation of a Mixture Online

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Middle Georgia State University *

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1012

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Chemistry

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Feb 20, 2024

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1 Separations of a Mixture Lab Online Name: __________________________ Please, do not forget to print or type your name out. Thanks Substances comprising mixtures can be separated based on the physical properties of the substances composing the mixture. Some separations may be as easy as removing large particles using a magnet if some of the solid particles are magnetic such as iron. Some particles of a substance can be removed by using tweezers such as copper metal since it is reddish in color. However, some substances cannot be removed using either of these techniques if none of them are magnetic, they have the same color, or they are such small particles they cannot be removed by using tweezers. Example of this is a mixture of sand and table salt. Salt can be separated successfully form sand using water, since table salt, or sodium chloride, is soluble in water but sand is not. After dissolving table salt in water to separate it from sand, water can be boiled off or allow to slowly evaporate away to obtain the table salt after separation from sand. In this lab, the components of a heterogeneous mixture of iron metal shot, copper metal shot, sand, and sodium chloride will be separated, and the mass percentage of each component in the mixture will be calculated. Mass % of Component A = Massof A ∈ Mixture Mass of Mixture × 100% Weigh out between 10.0 to 15.0 grams of the heterogeneous mixture using a metal scoopula (Figure 1) to transfer the heterogeneous mixture from its container to the plastic weight boat. Be sure to tare the balance to 0.0 grams right after placing the empty plastic weighing boat on the balance. Then add a quantity of the heterogeneous mixture between 10.0 to 15.0 grams. With the balance tared at 0.0 grams with the empty weighing boat on the balance, the measured mass in grams will be that from the heterogeneous mixture transferred and record the results below with description of mixture. Figure 1 Metal Scoopula, Plastic Weighing Boat and Top Loading Balance Removal of Iron Metal Shot Use a rectangular shaped magnet (Figure 2) to pick up all the iron metal shot in the mixture. Transfer the removed iron metal shot into a separate plastic weight boat. Then tare the balance to 0.0 grams with another empty plastic weighing boat and add the iron shot to determine the mass of iron shot to be tabulated in the data table on the next page and calculate percent mass of iron in the mixture to two significant figures.

2 Removal of Copper Metal Shot Using a pair of tweezers (Figure 2), pickup and remove one reddish color piece of copper metal shot at a time to put into an empty plastic weight boat. After removing all the copper shot, place another empty weight boat on the balance, and tare the balance to 0.0 grams with the second empty plastic weighing boat. Add the copper metal shot to the empty plastic weighing boat on the balance to determine the mass of copper shot. Tabulate the mass of copper metal shot extracted and calculate its percentage mass to two significant figures in the data table on the next page. Figure 2 Rectangular Magnets and Tweezers Separation of Table Salt from Sand After removal of the iron metal shot and copper metal shot, use a 20 mL beaker (Figure 3) to pour in the remaining mixture of sand and salt. Using distilled water bottle (Figure 3), rinse the plastic weighing boat containing the mixture of just sand and salt with a few milliliters of distilled water to ensure nearly all the sand and salt mixture has been transferred completely to the 20 mL beaker. Then add some additional distilled water until the 20 mL line has been attained with water. Figure 3 Picture of glass beakers (100 mL, 150 mL, 250 mL, 400 mL and 600 mL), Spatula, Glass Stirring Rod, Scoopula, and Distilled Water Bottle To dissolve the sodium chloride into the approximate 20 mL of distilled water, using a spatula or a glass stirring rod to stir the mixture for about 3 to 5 minutes. Afterwards, allow the sand to slowly settle at the bottom of the 20 mL beaker. Then decant carefully all the water containing dissolved sodium chloride into a 600 mL beaker. To dry the sand as much as possible of remaining moisture, place the 20 mL beaker with moist sand on top of a hotplate (Figure 4) on moderate heating. Stir gently the sand around until it is nearly dried out. Then, using crucible tongs (Figure 4) pick up the hot 20 mL beaker containing the nearly dry sand and let it cool on a square wire gauze on the lab tabletop. Figure 4 Electrically Powered Hotplate, Crucible Tongs, and Square Wire Gauze

3 After cooling to room temperature, then using a scoopula or spatula (Figure 4) carefully transfer as much dried sand as possible onto another empty plastic weighing boat. Then with the top loading balance tared to 0.0 gram with another empty weighing boat, transfer the dry sand into the empty weighing boat on the balance to get the mass of sand. Record the mass of the sand and percentage mass to two significant figures using the data table below. To Separate the Dissolved Sodium Chloride from 20 mL of Water Again, using the hotplate, placed the 600 mL beaker containing the 20 mL of water with dissolved sodium chloride on the center of the hotplate. Turn to maximum heat in order to boil nearly all the water to obtain the dissolved sodium chloride. In this heating, be extra careful since maximum heating is applied to keep the water boiling constantly around 100ºC. When nearly all the water has boiled away, the solid sodium chloride appears. To avoid too much heating which can cause the 600 mL beaker to crack and break apart, when one hears the popping sound of the salt then it is time to turn off the hotplate. Using large crucible tongs, place the 600 mL beaker containing nearly dried out sodium chloride onto the wire gauze as before. When the 600 mL beaker has cooled to nearly room temperature and is safe to handle, use the scoopula or spatula to remove as much salt as possible from the 600 mL beaker into an empty plastic weighing boat. Then using another empty plastic weighing boat resting on the top loading balanced tared to 0.0 grams, add the sodium chloride to obtain the mass of sodium chloride retrieved, and report this mass in the data table. Calculate the mass percent composition of all components using the equation the first page and give a description of each separated component.

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4 Data of Heterogeneous Mixture Mass (grams) Description 14.0 Light brown powder that contains small pieces of metal Data of Separated Components Replace question marks with calculated mass percent values or write them near the question marks. All numbers in Table have only 2 significant figures! Except Total Mass of Mixture which is 3 sig. fig. Go to the given URL to see similar experiments: https://www.youtube.com/watch?v=RukdGJ4bWdQ Component Mass (grams) Mass % Description Iron (Fe) 2.4 2.4 14.0 × 100 = ? Small brownish colored pieces of metal that stick to a magnet Copper (Cu) 5.1 5.1 14.0 × 100 = ? Small reddish colored pieces of metal that do not stick to a magnet Sand (SiO 2 ) 3.0 3.0 14.0 × 100 = ? Light brown powder Salt (NaCl) 3.5 3.5 14.0 × 100 = ? White powder Total mass of mixture = 2.4 grams + 5.1 grams + 3.0 grams + 3.5 grams = ? grams (3 significant figures) Post-Lab Questions Changed to bold print, circle with pen or pencil, or highlight in yellow for your answers in the following multiple-choice questions. 1. What properties did you use to determine which metal pieces were iron or copper? a) Magnetism since iron sticks to a magnet and not copper b) Color since small iron pieces are dark in color and copper is red. c) Both of these 2. Name 2 things you learned about heating liquids on a hot plate. a) Heating liquids is as hazardous as cooking food on a stove or in an oven b) It takes time to heat liquids as well as cooking one’s food. c) Both of these 3. Could you separate a mixture of sugar and salt using the water solution method? a) Yes, because they both dissolve in water. b) No, because they both are soluble in water.

5 Pre-Lab Questions Changed to bold print, circle with pen or pencil, or highlight in yellow for your answers in the following multiple-choice questions. 1. Which of the following properties could be used to differentiate iron, copper and lead from one another? a) Color, since small pieces of iron and lead appear dark colored while copper pieces are red. b) Magnetism since iron sticks to a magnet, but copper and lead do not. c) Both of these 2. If you had two solids that were soluble in water, which one of the following techniques is the best to separate them? a) Change to another liquid solvent, which will only dissolve one of the two different solids. b) Use a pair of tweezers to pick out the tiny crystals of one of the two solids. c) Melt one of the two solids at the lower melting point of the two. d) Use gravity filtration 3. If a sample contained 12.015 g of sand, 0.988 g of sodium chloride and 8.523 g of copper shot, what is the percentage of each component in the mixture? Replace question marks with calculated mass percent values or write them near the question marks. 12.015 grams 0.988 gram + 8.523 grams ? grams (5 significant figures ) % Sand = 12.015 21.526 × 100% = ? % ( 5 significant figures ) % NaCl = 0.988 21.526 × 100% = ? % ( 3 significant figures ) % Copper = 8.523 21.526 × 100% = ? % ( 4 signifincant figures )