What is Flask?
[[File:Erlenmeyer flask hg.jpg|thumb|An [[Erlenmeyer flask]] or conical flask]] A '''flask''' is a type of [[container]] made of [[glass]]. They are a common piece of [[Laboratory equipment|apparatus]] used in [[laboratory|laboratories]]. Their size are chosen by the [[volume]] they can hold, and is measured in [[metric unit]]s, like [[litre]]s (L) or [[millilitre]]s (mL). Their shape depends on what they are used for, but they usually consist of a wider body, which contains the materials, and a more narrow [[neck]] with an opening at the top. The opening is the way to insert materials into the body. Some flasks have more than one neck and opening at the top. Flasks are used to contain [[substance]]s. They are usually made of [[glass]] or [[borosilicate glass]] ([[Pyrex]]). This is to ensure that the substances inside the flask do not react with the flask itself, due to the volatile nature of many chemicals (such as [[hydrochloric acid]]), They can be used to [[heat]] a substance. There are many different types of laboratory flasks. They differ in their shape and what they are used for. The most common types of flask are: * [[Erlenmeyer flask]] * [[Florence flask]] * [[Volumetric flask]] * [[Büchner flask]] * [[:en:Fernbach_flask|Fernbach flask]] Flasks can be used to make and hold solutions, to measure chemicals, and to contain chemical reactions like [[boiling]], [[precipitation]] and [[chemical analysis|analysis]]. {{-}} <gallery> File:Round-bottom flasks.PNG|[[Round-bottom flask]]&mdash;a flask with a round body and one or more necks with ground glass joints. File:My retort.jpg|[[Retort]]&mdash;a round vessel with a long downward-pointing neck. File:Round bottomed flask half full.png|[[Florence flask]]&mdash;a flask with a round body and one longer neck without a ground glass joint. File:Buchner Flask.PNG|[[Büchner flask]] or sidearm flask&mdash;a flask with thick walls and a short tube for connection of a hose on the side of its neck. File:Volumetric flask.PNG|[[Volumetric flask]]&mdash;a flask used for p