Engineering
The pace of progress in the renewable energy sector is limited not only by the technology to capture energy from the sun, the wind, the oceans or the Earth's radiant heat, but also by the ability to effectively store and ...
Sep 8, 2021
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326
Engineering
A team of researchers affiliated with multiple institutions in China has developed a micro-fiber based metafabric that provides wearers with daytime radiative cooling. In their paper published in the journal Science, the ...
Energy & Green Tech
A team from the Helmholtz-Zentrum Berlin, Ulm University, and Heidelberg University has now investigated how hydrogen can be produced at the South Pole using sunlight, and which method is the most promising. Their conclusion: ...
Jul 2, 2021
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4
Engineering
A researcher at University of Limerick has developed a low-cost, environmentally friendly sensor that can detect damage in pipelines and could save water as a result.
May 12, 2021
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167
Energy & Green Tech
As ethanol, biodiesel, and other biofuels continue to present challenges, such as competing with food security or lacking the technology for more efficient and low-cost production, microalgae are gaining momentum as a biofuel ...
Mar 30, 2021
2
105
Engineering
A new type of 3D-printed battery which uses electrodes made from vegetable starch and carbon nanotubes could provide mobile devices with a more environmentally-friendly, higher-capacity source of power.
Mar 22, 2021
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435
Engineering
A joint research team, affiliated with UNIST has unveiled a novel electrolyte additive that could enable a long lifespan and fast chargeability of high-energy-density lithium-ion batteries (LIBs).
Mar 18, 2021
1
106
Electronics & Semiconductors
Modern electronics is approaching the limit of its capabilities, which is determined by the fundamental laws of physics. Therefore, the use of classical materials, for example, silicon, is no longer able to meet the requirements ...
Mar 2, 2021
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7
Energy & Green Tech
Natural gas is the cleanest of all fossil fuels, but storing it safely and affordably remains a challenge. Now, engineers from the National University of Singapore (NUS) have devised a method to convert natural gas into a ...
Dec 3, 2020
2
8
Energy & Green Tech
A new process for restoring spent cathodes to mint condition could make it more economical to recycle lithium-ion batteries. The process, developed by nanoengineers at the University of California San Diego, is more environmentally ...
Nov 12, 2020
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77
An acid (from the Latin acidus/acēre meaning sour) is a substance which reacts with a base. Commonly, acids can be identified as tasting sour, reacting with metals such as calcium, and bases like sodium carbonate. Aqueous acids have a pH of less than 7, where an acid of lower pH is typically stronger, and turn blue litmus paper red. Chemicals or substances having the property of an acid are said to be acidic.
Common examples of acids include acetic acid (in vinegar), sulfuric acid (used in car batteries), and tartaric acid (used in baking). As these three examples show, acids can be solutions, liquids, or solids. Gases such as hydrogen chloride can be acids as well. Strong acids and some concentrated weak acids are corrosive, but there are exceptions such as carboranes and boric acid.
There are three common definitions for acids: the Arrhenius definition, the Brønsted-Lowry definition, and the Lewis definition. The Arrhenius definition states that acids are substances which increase the concentration of hydronium ions (H3O+) in solution. The Brønsted-Lowry definition is an expansion: an acid is a substance which can act as a proton donor. Most acids encountered in everyday life are aqueous solutions, or can be dissolved in water, and these two definitions are most relevant. The reason why pHs of acids are less than 7 is that the concentration of hydronium ions is greater than 10−7 moles per liter. Since pH is defined as the negative logarithm of the concentration of hydronium ions, acids thus have pHs of less than 7. By the Brønsted-Lowry definition, any compound which can easily be deprotonated can be considered an acid. Examples include alcohols and amines which contain O-H or N-H fragments.
In chemistry, the Lewis definition of acidity is frequently encountered. Lewis acids are electron-pair acceptors. Examples of Lewis acids include all metal cations, and electron-deficient molecules such as boron trifluoride and aluminium trichloride. Hydronium ions are acids according to all three definitions. Interestingly, although alcohols and amines can be Brønsted-Lowry acids as mentioned above, they can also function as Lewis bases due to the lone pairs of electrons on their oxygen and nitrogen atoms.
This text uses material from Wikipedia, licensed under CC BY-SA
