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The 48 experiments in this well-conceived manual illustrate important concepts and principles in general, organic, and biochemistry. As in previous editions, three basic goals guided the development of all the experiments: (1) the experiments illustrate the concepts learned in the classroom; (2) the experiments are clearly and concisely written s | Laboratory Experiments for General Organic and Biochemistry fawth rdilion Bcttclhcim Landesberg Experiment Laboratory techniques use of the laboratory gas burner basic glassworking I Background The Laboratory Gas Burner Tirrill or Bunsen burners provide a ready source of heat in the chemistry laboratory. In general since chemical reactions proceed faster at elevated temperatures the use of heat enables the experimenter to accomplish many experiments more quickly than would be possible at room temperature. The burner illustrated in Fig. 1.1 is typical of the burners used in most general chemistry laboratories. Figure 1.1 The Bunsen burner. Violet outer cone Pale-blue middle cone Dark-blue inner cone Air vents Gas control valve Base Hottest part of the flame 800 C Main gas valve A burner is designed to allow gas and air to mix in a controlled manner. The gas often used is natural gas mostly the highly flammable and odorless hydrocarbon methane CH4. When ignited the flame s temperature can be adjusted by altering the various proportions of gas and air. The gas flow can be controlled either at the main gas valve or at the gas control valve at the base of the burner. Manipulation of the air vents at the bottom of the barrel allows air to enter and mix with the gas. The hottest flame has a violet outer cone a pale-blue middle cone and a dark-blue inner cone the air vents in this case are opened sufficiently to assure complete combustion of the gas. Lack of air produces a cooler luminous yellow flame. This flame lacks the inner cone and most likely is smoky and often deposits soot on objects it contacts. Too much air blows out the flame. Harcourt Inc. Experiment 1 1 Basic Glassworking In the chemistry laboratory it is often necessary to modify apparatus made from glass or to connect pieces of equipment with glass tubing. Following correct procedures for working with glass especially glass tubing is important. Glass is a super-cooled liquid. Unlike crystalline solids which
