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The term molality is formed in analogy to molarity which is the molar concentration of a solution. The earliest known use of the intensive property molality and of its adjectival unit, the now-deprecated molal, appears to have been published by G. N. Lewis and M. Randall in the 1923 publication of Thermodynamics and the Free Energies of Chemical Substances. [3]
The concentration of pure osmium tetroxide (molar mass = 254.23 g/mol) is c(OsO 4) = 5.1 kg/L / 254.23 g/mol = 20.1 mol/L. A typical protein in bacteria, such as E. coli, may have about 60 copies, and the volume of a bacterium is about 10 −15 L. Thus, the number concentration C is C = 60 / (10 −15 L) = 6 × 10 16 L −1. The molar ...
Even in dispersive media, the frequency f of a sinusoidal wave is equal to the phase velocity v of the wave divided by the wavelength λ of the wave: =. In the special case of electromagnetic waves in vacuum , then v = c , where c is the speed of light in vacuum, and this expression becomes f = c λ . {\displaystyle f={\frac {c}{\lambda }}.}
For example, LH 2 /LO 2 bipropellant produces higher I sp (due to higher chemical energy and lower exhaust molecular mass) but lower thrust than RP-1/LO 2 (due to higher density and propellant flow). In many cases, propulsion systems with very high specific impulse—some ion thrusters reach 25x-35x better I sp than chemical engines—produce ...
The total dependency ratio is the total numbers of the children (ages 0–14) and elderly (ages 65+) populations per 100 people of adults (ages 15–64). A high total dependency ratio indicates that the adult population and the overall economy face a greater burden to support and provide social services for youth and elderly persons, who are often economically dependent.
The Democracy Ranking is an index compiled by the Association for Development and Advancement of the Democracy Award, an Austria-based non-partisan organization. [1] [2] Democracy Ranking produces an annual global ranking of liberal democracies.
Part B consists of a variety of authentic audio materials, including interviews, podcasts, public service announcements, conversations, and brief presentations. This section is divided into two subsections. In the first, the audio texts are paired with print materials; the second consists solely of audio texts.
South Africa, officially the Republic of South Africa (RSA), is the southernmost country in Africa.Its nine provinces are bounded to the south by 2,798 kilometres (1,739 miles) of coastline that stretches along the South Atlantic and Indian Ocean; [15] [16] [17] to the north by the neighbouring countries of Namibia, Botswana, and Zimbabwe; to the east and northeast by Mozambique and Eswatini ...