Oncology & Cancer

Scientists find new way to block cancer-causing HPV virus

The human papillomavirus (HPV) is the main cause of several cancers, including cervical cancer, which kills almost 300,000 women around the world each year. Although vaccines offer a proven first line of defense against HPV ...

Medical research

Engineered botox is more potent and safer in mice

Botulinum toxin (BoNT) is used for a range of applications from treating chronic pain to reducing the appearance of wrinkles, but when injected it can diffuse into the surrounding tissue and give rise to adverse effects. ...

Medical research

Protein controls fat metabolism

Many foods—whether it's the mozzarella on your favorite pizza, the olive oil in salad dressing or hollandaise sauce during asparagus season—contain lots of fat. The fatty acids in these foods are among the essential nutrients ...

Oncology & Cancer

Deadlier colon cancer develops differently in women and men

Researchers have found that colon cancer tumor cells produce energy for growth differently in women and men, and that this difference is associated with a more aggressive form of tumor growth with a higher incidence in women.

Medications

Acid reflux drugs linked to increased fracture risk in kids

Proton pump inhibitors—a widely used class of drugs used to treat acid reflux and related symptoms—may lead to an increased risk of fractures in children and adolescents, reports a study in the Journal of Pediatric Gastroenterology ...

Medical research

Cellular stress makes obese mothers have obese babies

Maternal obesity increases the risk for obesity and metabolic perturbations in their offspring, but what are the mechanisms? In a new study published March 12 in the open-access journal PLOS Biology, Sebastien Bouret of the ...

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Acid

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