A guided inquiry-based approach to the freshman chemistry laboratory.An inquiry-based approach to the freshman chemistry laboratory creates excitement and demands critical thinking. Instead of solving a puzzle with all pieces given, the students must discover the missing pieces and then solve the puzzle. Our approach involves a crime scene where a drug dealer, known for cutting his cocaine cocaine (kōkān`, kō`kān), alkaloid drug derived from the leaves of the coca shrub. A commonly abused illegal drug, cocaine has limited medical uses, most often in surgical applications that take advantage of the fact that, in with a pure household white powder, was found dead in an alley alley an area in a cow barn identified by its particular purpose such as a loafing alley, a walking alley or feeding alley. . A trace amount of cocaine mixed with an unknown powder was found on a handgun in a nearby dumpster. Three suspects were caught with packets of impure im·pure adj. im·pur·er, im·pur·est 1. Not pure or clean; contaminated. 2. Not purified by religious rite; unclean. 3. Immoral or sinful: impure thoughts. cocaine and brought in for questioning. One piece of evidence that could help crack this case is the identity of the white powder that was mixed in the samples of the cocaine. Students are provided four samples of the unknown pure white powders separated from each of the suspect and victim's cocaine. Their job is to determine who is most likely guilty as well as the identity of the unknown white powders using techniques learned in the laboratory. These techniques include solubility solubility Degree to which a substance dissolves in a solvent to make a solution (usually expressed as grams of solute per litre of solvent). Solubility of one fluid (liquid or gas) in another may be complete (totally miscible; e.g. analysis, density determination, observing a melting point melting point, temperature at which a substance changes its state from solid to liquid. Under standard atmospheric pressure different pure crystalline solids will each melt at a different specific temperature; thus melting point is a characteristic of a substance and , and measuring conductivity conductivity /con·duc·tiv·i·ty/ (kon?duk-tiv´i-te) the capacity of a body to transmit a flow of electricity or heat; the conductance per unit area of the body. con·duc·tiv·i·ty n. 1. . Based on experimental data, students are able to compare the samples to determine the guilty party as well as to compare their data to known values to help conclude the identity of the unknown pure white powder. An inquiry-based laboratory forces students to rely on mastery of techniques and discovery of unknowns to solve the problem. Students are challenged and show greater ownership in the solution of the problem. |
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