Density & Phase Experiments: Cork, Nylon, Cola, Lead, Mercury, Bromine, Dry Ice, Liquid Ni, Study notes of Chemistry

Download Density & Phase Experiments: Cork, Nylon, Cola, Lead, Mercury, Bromine, Dry Ice, Liquid Ni and more Study notes Chemistry in PDF only on Docsity! DENSITY COLUMN This is a display. The column consists of 5 liquid layers (3 organic layers and 2 aqueous layers) with 3 solids floating in them. The order of density is: Location Material and Phase* ρ (g/mL) Top Cork(s) [a tree bark] 0.34 C6H14(l) [n-hexane] 0.66 H2O(l) [water] 1.00 ↓ (C6H11NO)∞(s) [nylon] 1.14 CH2Cl2(l) [dichloromethane] 1.32 NaBr(aq) [saturated solution] 1.61 (C2F4)∞(s) [teflon] 1.74 Bottom CHBr3(l) [bromoform] 2.89 * (s) ≡ solid; (l) ≡ liquid; (aq) ≡ aqueous solution. Note: Dye or a very small amount of iodine has been added to color the layers. DENSITY OF COLA AND DIET COLA Apparatus and Materials: 1. Cans of regular cola and diet cola. 2. 4L beaker of water. Procedure: Place both cans in the beaker of water. The regular cola will sink to the bottom while the diet cola will float. (make sure no air is trapped underneath the cans or they will both float). Discussion: Regular cola is about 10% sugar by mass; sugar is much denser than water. A much smaller mass of artificial sweetener is needed in diet cola to achieve the same sweetness. SUBLIMATION OF DRY ICE Apparatus and Materials 1. Dry ice. 2. Balloons. 3. Cylinder. Procedure Place several pieces of dry ice into the cylinder and then attach the balloon over the mouth of the cylinder. This balloon will inflate from the pressure of the gaseous carbon dioxide generated as the dry ice sublimes. Discussion Sublimation Point of CO2: −78.4 ˚C at atmospheric pressure. LIQUID NITROGEN Apparatus and Materials: 1. large dewar of liquid nitrogen 2. gloves 3. tongs or forceps 4. flowers 5. balloon 6. rubber tubing Procedure: The following items are available for immersing in the liquid nitrogen: a. Fresh flowers: They will crumble easily after being dunked in liquid nitrogen. b. Balloons filled with air: show the decrease in the gas volume with decreasing temperature. c. Rubber ball or rubber tubing: show how they become brittle. Discussion: N2: mp –210 ˚C, bp –196 ˚C. At room temperature the flowers contain a lot of liquid water, and the rubber objects are really more like slow-flowing liquids than solids. Only at much lower temperatures do these “solid” materials show the properties of solids. SEPARATION OF MIXTURES USING PHYSICAL PROPERTIES Solid-Solid: Separate sugar and iron with a magnet or by dissolving the sugar in water. 1. iron filings 2. sucrose 3. large white stir bar 4. beaker of water Solid-Liquid: Evaporate water from a brine solution (bp H2O = 100 ˚C; bp NaCl = 1,547 ˚C) 1. salt water mixture 2. crystallizing dish 3. hot plate Liquid-Liquid: Distill methanol. The distillate can be lit with a match. Allow at least 30 minutes for the distillation. (bp CH3OH = 65 ˚C; bp H2O = 100 ˚C) 1. 50:50 methanol and H2O mixture 2. blue dye 3. distillation apparatus with thermometer 4. thermo well heater and lab jacks 5. graduated cylinder 6. small crystallizing dish 7. matches Liquid-Gas: Shake a can of carbonated beverage. Open the can and show the release of gas (CO2, like all gases, is less soluble in water as temperature increases).