Mass fraction (chemistry)

In chemistry, the mass fraction is the ratio of one substance with mass to the mass of the total mixture , defined as

The sum of all the mass fractions is equal to 1:

Mass fraction can also be expressed, with a denominator of 100, as percentage by mass (frequently, though erroneously, called percentage by weight, abbreviated wt%). It is one way of expressing the composition of a mixture in a dimensionless size; mole fraction (percentage by moles, mol%) and volume fraction (percentage by volume, vol%) are others.

For elemental analysis, mass fraction (or "mass percent composition") can also refer to the ratio of the mass of one element to the total mass of a compound. It can be calculated for any compound using its empirical formula or its chemical formula

Terminology

"Percent concentration" does not refer to this quantity. This improper name persists, especially in elementary textbooks. In biology, the unit "%" is sometimes (incorrectly) used to denote mass concentration, also called "mass/volume percentage." A solution with 1 g of solute dissolved in a final volume of 100 mL of solution would be labeled as "1 %" or "1 % m/v" (mass/volume). This is incorrect because the unit "%" can only be used for dimensionless quantities. Instead, the concentration should simply be given in units of g/mL. "Percent solution" or "percentage solution" are thus terms best reserved for "mass percent solutions" (m/m = m% = mass solute/mass total solution after mixing), or "volume percent solutions" (v/v = v% = volume solute per volume of total solution after mixing). The very ambiguous terms "percent solution" and "percentage solutions" with no other qualifiers continue to occasionally be encountered.

WT

WT or Wt may refer to:

In science

In technology

Other uses

Wt (web toolkit)

Wt (pronounced "witty") is an open source widget-centric web application framework for the C++ programming language developed by Emweb. It has an API that resembles the C++ desktop application library Qt, also using a widget tree and event-driven signal/slot programming model.

The goal of the library is to benefit from the stateful component model used in desktop applications APIs, applied to web development, instead of the traditional model–view–controller (MVC) model. Rather than using MVC at the level of a page, MVC is pushed to the level of individual components.

While the library uses a desktop application development model, it does support web-specific features including semantic URLs and browser history navigation support.

A unique feature of the library is its abstraction layer of the browser rendering model. The library uses Ajax for communicating with Ajax-capable browsers, while using plain HTML form post-backs for other user agents. Using a progressive bootstrap method, the user interface is initially rendered as plain HTML, and for Ajax-capable browsers, it is automatically upgraded to use Ajax for increased interactivity. In this way, it is the only server-side framework that implements progressive enhancement automatically, and the only Ajax framework with search engine optimization (SEO) qualities.