Lab Techniques for Heating Materials
- A gas burner is a flame, made out of a gas (such as propane), that is used to heat materials. The most common type of gas burner in the lab is a Bunsen burner. It uses methane gas, mixed with oxygen, to fuel a single flame. The flame on a Bunsen burner can be adjusted by a valve on the side of burner. A Bunsen burner flame can get as hot as 1,500 degree Celsius (around 2,700 degrees Fahrenheit). A Bunsen burner is effective in warming the contents of a smaller object, like a beaker or test tube.
- A hot plate is a surface that can be heated by a gas burner, but also is commonly heated by electricity. Hot plates have the advantage of being able to be set to cycle "on" and "off." This feature may be an important aspect of an experiment (e.g., comparing how a substance looks at certain temperatures). Substances placed in a glass dish (which is placed on the hot plate) are ideal for hot-plate heating; this often includes liquid mixtures.
- A heating mantle is a piece of equipment is similar to a Crockpot in cooking; it is often circular, and has a layer of insulation that separates the heat source from the substance being heated. Thus, much like a heat bath, you can place a substance in a glass container, and then place the container in the heating mantle. Heating mantles are commonly heated by an electrical source, not a gas source.
- The previous techniques dealt primarily with heating substances for experiments. It is also important to apply heat to lab equipment between experiments to sterilize the equipment and not contaminate subsequent experiments. Methods for heating lab equipment include sterilizing with moist heat: the University of Kansas lab method instructions, for example, suggest 15 minutes in a pressure cooker for smaller equipment. A dry heat sterilization method is used, too, such as placing the equipment in the oven for at least two hours.
