From the simple glass test tube to the thermally insulated flasks for storing flammable liquids in controlled temperatures, flasks vary in design to suit the purpose. Flasks are essential in laboratories. Used in many fields of scientific research such as marine biology, geology and medical science, they also serve industrial needs.
The volumetric flask is analytical glassware. In the lab it is used for preparing solutions of known concentration in exact amounts. The volumetric flask is etch-marked to measure the volume of the solution inside precisely. The solid material used in the solution must be dissolved completely in less water than is needed to fill the flask to the etchmark. To be sure the measurement is exact, an eyedropper is used to add water to the fill line. The flask should be clean and dry to begin, with no drops left clinging to the inside of the neck as the water is dropped in. These drops could result in inaccuracy of measurement if they roll into the liquid after measuring.
The Erlenmeyer Flask
The Erlenmeyer flask (conical flask) is probably of greater use in most laboratories than any other. The flask was invented by Emil Erlenmeyer in 1861. Now usually made of Pyrex, this flask is used for storing, mixing or heating chemicals. It has a narrow top that can be sealed with a stopper. When unsealed, the flask is often used as a beaker. The round-bottom flask, referred to as an Erlenmeyer bulb, is another of the same type of flask. It is kept upright with a cork ring. When used to heat a solution, the rounded bottom absorbs heat more evenly than does the conical Erlenmeyer flask.
Flasks for Science and Industry
There are many needs for flasks in both industry and in scientific research, and there are many kinds of flasks to fill those needs. Each is used for a specific purpose and may be called by another name, but, in fact, many are just modified versions of one of the more common flasks in the laboratory, such as the Erlenmeyer flask.There are boiling flasks, filtering flasks, multiple-neck flasks and reaction flasks. The distillation flask usually has a narrow neck and a side tube for distillation purposes. Flasks used for industrial purposes vary in size from the smaller lab glassware to huge containers used for shipping purposes and sizes in between, such as oxygen tanks or storage of propane and other gases.
The Dewar Flask
Vacuum flasks are used for a variety of purposes. Commonly thought of as the Thermos we all know, the vacuum flask was invented in 1891 by Sir James Dewar, a Scottish chemist and physicist. Its original purpose was to contain liquid nitrogen at controlled temperatures. The double-walled flask, actually a bottle within a bottle, was fused at the neck to seal the vacuum created between the walls. The vacuum protects the contents of the flask from outside heat. Now the Dewar flask has many other uses. Seed storage containers are patterned from the Dewar flask. The flask is used in laboratories to hold tissue cultures and transport or store flammable liquid gases. The Dewar flask even played a part in the success of NASA's Apollo 11 lunar mission.