Separation of Pure Substances and Mixtures Lab abx,9180,1.pdf
Methods Used to Separate Pure Substances and Mixtures
Separation by Crystallization Crystal growth is accomplished through the process of self-assembly. Crystals like salt (halite) are made of ions. The resulting crystal formations are ionic crystals. Crystals made of atoms, such as silicon, are atomic crystals and crystals composed of molecules such as sucrose (sugar, C12H22O11) are molecular crystals. Make a saturated solution. 1. Start with approximately 250ml of distilled water in a 600 mL beaker. 2. Bring it to a slow boil and add a teaspoon or two of your chemical. 3. When this dissolves, add more. Keep adding and stirring chemical until no more will dissolve. This is a saturated solution. 4. Carefully, pour this solution into a clean beaker. 5. Suspend a string into the beaker from a pencil laid across the top of the glass. Tie a paper clip at the lower end of the string so it hangs straight down. 6. Allow the set up to cool slowly. Left undisturbed, the crystals should grow larger every day until the solution runs dry. 7. Record observations 8. Clean up
Separation by Density Procedure Prepare 4 solutions of approximately 10mL each as directed below. Review the procedure and determine which solution should go into the tube first and so is the solution to be made first. 1. Mix 10mL water and no sodium chloride. 2. Mix 10mL water and 1 scoop of sodium chloride. Use a stirring rod to speed up salvation. For a scoop measurement used the small weighing boat. Add food coloring ( 1 drop is all you need) 3. Mix 10mL water and 2 scoop of sodium chloride. And directions from step 2 4. Mix 10mL water and 3 scoops of sodium chloride. 5. Place the solutions in a single large test tube to make a density tube. 6. Leave density tube standing 7. Record observations 8. Clean Up: All liquids can go down the sink. Be sure to wash glassware with Alconox and thoroughly rinse. Return materials to location where you found them.
Separation by Chemical Reaction Background: A single replacement reaction, sometimes called a single displacement reaction, is a reaction in which one element is substituted for another element in a compound. The starting materials are always pure elements, such as a pure zinc metal or hydrogen gas, plus an aqueous compound. When a replacement reaction occurs, a new aqueous compound and a different pure element will be generated as products. The general pattern of a single replacement reaction is shown below. AB(aq) + C CB(aq) + A Procedure 1. From the side bench obtain a piece of copper wire. Be sure it is clean. Coil the wire so that it will fit into the test tube without touching the bottom. 2. From the side bench, using the designated pipette half fill a clean dry micro test tube with silver nitrate solution ( be careful silver nitrate will stain you skin and clothing) 3. Return to your bench and place the copper wire in the silver nitrate solution so that the wire is not touching the bottom and approximately 1 inch is covered in solution. 4. Let stand for at least 10 minutes 5. Record observations. Continue onto next procedure but leave this reaction to develop. 6. To clean up this lab, use filtration to separate the solid from the liquid phase. 7. Clean Up. NOTHING from this lab goes down the sink. Place the waste solution, filter paper with filtrate and copper in the designated containers in the fume hood. Return the materials to the location where you found them.
Separation of Water by Electrolysis Background: Decomposition Reaction. A compound’s bonds are broken to produce the constituent elements. The general form for this type of reaction is: AB A + B 1. At your bench fill 3/4 of a Petri dish with tap water. Add one scoop of baking soda (NaHCO3) into the Petri dish. Dissolve completely using a stirring rod. 2. Use a pipet to add 2-3 drops of bromothymol blue solution into the petri dish until the blue color can easily be observed. If necessary, you may gently swirl to be sure the color is even throughout. Bromothymol blue is a pH indicator.
3. Create and Place the Electric Circuit: Connect the cap to the terminal of the battery. Connect a piece of graphite to each clip. Do not allow ends to touch each other. Place the graphite into the Petri dish. Do not allow the ends to touch each other. 4. Record observations 5. Remove the electric circuit from the Petri dish. Do not allow the ends to touch. 6. Record observations 7. Remove the cap from the battery and save. Remove and save the graphite pieces. 8. Clean the clips and graphite with distilled water. 9. Clean up. Dispose of water solution in the designated container in the fume hood. Return all materials
Separation by Crystallization Crystal growth is accomplished through the process of self-assembly. Crystals like salt (halite) are made of ions. The resulting crystal formations are ionic crystals. Crystals made of atoms, such as silicon, are atomic crystals and crystals composed of molecules such as sucrose (sugar, C12H22O11) are molecular crystals. Make a saturated solution. 1. Start with approximately 250ml of distilled water in a 600 mL beaker. 2. Bring it to a slow boil and add a teaspoon or two of your chemical. 3. When this dissolves, add more. Keep adding and stirring chemical until no more will dissolve. This is a saturated solution. 4. Carefully, pour this solution into a clean beaker. 5. Suspend a string into the beaker from a pencil laid across the top of the glass. Tie a paper clip at the lower end of the string so it hangs straight down. 6. Allow the set up to cool slowly. Left undisturbed, the crystals should grow larger every day until the solution runs dry. 7. Record observations 8. Clean up
Separation by Density Procedure Prepare 4 solutions of approximately 10mL each as directed below. Review the procedure and determine which solution should go into the tube first and so is the solution to be made first. 1. Mix 10mL water and no sodium chloride. 2. Mix 10mL water and 1 scoop of sodium chloride. Use a stirring rod to speed up salvation. For a scoop measurement used the small weighing boat. Add food coloring ( 1 drop is all you need) 3. Mix 10mL water and 2 scoop of sodium chloride. And directions from step 2 4. Mix 10mL water and 3 scoops of sodium chloride. 5. Place the solutions in a single large test tube to make a density tube. 6. Leave density tube standing 7. Record observations 8. Clean Up: All liquids can go down the sink. Be sure to wash glassware with Alconox and thoroughly rinse. Return materials to location where you found them.
Separation by Chemical Reaction Background: A single replacement reaction, sometimes called a single displacement reaction, is a reaction in which one element is substituted for another element in a compound. The starting materials are always pure elements, such as a pure zinc metal or hydrogen gas, plus an aqueous compound. When a replacement reaction occurs, a new aqueous compound and a different pure element will be generated as products. The general pattern of a single replacement reaction is shown below. AB(aq) + C CB(aq) + A Procedure 1. From the side bench obtain a piece of copper wire. Be sure it is clean. Coil the wire so that it will fit into the test tube without touching the bottom. 2. From the side bench, using the designated pipette half fill a clean dry micro test tube with silver nitrate solution ( be careful silver nitrate will stain you skin and clothing) 3. Return to your bench and place the copper wire in the silver nitrate solution so that the wire is not touching the bottom and approximately 1 inch is covered in solution. 4. Let stand for at least 10 minutes 5. Record observations. Continue onto next procedure but leave this reaction to develop. 6. To clean up this lab, use filtration to separate the solid from the liquid phase. 7. Clean Up. NOTHING from this lab goes down the sink. Place the waste solution, filter paper with filtrate and copper in the designated containers in the fume hood. Return the materials to the location where you found them.
Separation of Water by Electrolysis Background: Decomposition Reaction. A compound’s bonds are broken to produce the constituent elements. The general form for this type of reaction is: AB A + B 1. At your bench fill 3/4 of a Petri dish with tap water. Add one scoop of baking soda (NaHCO3) into the Petri dish. Dissolve completely using a stirring rod. 2. Use a pipet to add 2-3 drops of bromothymol blue solution into the petri dish until the blue color can easily be observed. If necessary, you may gently swirl to be sure the color is even throughout. Bromothymol blue is a pH indicator.
3. Create and Place the Electric Circuit: Connect the cap to the terminal of the battery. Connect a piece of graphite to each clip. Do not allow ends to touch each other. Place the graphite into the Petri dish. Do not allow the ends to touch each other. 4. Record observations 5. Remove the electric circuit from the Petri dish. Do not allow the ends to touch. 6. Record observations 7. Remove the cap from the battery and save. Remove and save the graphite pieces. 8. Clean the clips and graphite with distilled water. 9. Clean up. Dispose of water solution in the designated container in the fume hood. Return all materials
