Answering a century-old question on the origins of life

The missing link isn't a not-yet-discovered fossil, after all. It's a tiny, self-replicating globule called a coacervate droplet, developed by two researchers in Japan to represent the evolution of chemistry into biology.

Canaries volcano spews ash after brief pause

A volcano on Monday began again spewing out ash after a brief lull in the Canary Islands, where coastal residents are confined to their homes over fears of toxic gases when the lava hits the sea.

Engineers introduce a new approach for recycling plastics

Each human being uses, on average, 30 kg of plastic per year. Given that global life expectancy currently stands at approximately 70 years, each person will discard some two metric tons of plastic in his or her lifetime. ...

Researchers translate insect defense chemicals into eerie sounds

Sawfly larvae protect themselves by secreting cocktails of unpleasant, volatile chemicals intended to repel predators, particularly ants. Researchers can assess the effectiveness of these defenses by staging meetups, so-called ...

Earthly lava tubes may offer insights into extraterrestrial life

Since 1997, NASA has successfully landed five rovers on Mars. The rovers have beamed back data that indicate life cannot survive on the Martian surface; we do not know whether life persists below the ground, however. For ...

Are there DBPs in that cup of tea?

Surpassed only by water, tea is the second most consumed beverage worldwide. When boiled tap water is used to brew tea, residual chlorine in the water can react with tea compounds to form disinfection byproducts (DBPs). Now, ...

Downtime at the nerve cell's protein factories

Charcot-Marie-Tooth disease (CMT) is a rare hereditary condition. It occurs when genetic changes disrupt the transmission of nerve signals from the brain to the muscles of the extremities, particularly those of the lower ...

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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