alkaline
Chemistry
(adjective)
Having a pH greater than 7.
Biology
(adjective)
having a pH greater than 7; basic
Examples of alkaline in the following topics:
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The Alkaline Earth Metals
- The alkaline earth metals comprise the group 2 elements.
- All the discovered alkaline earth metals occur in nature.
- In chemical terms, all of the alkaline metals react with the halogens to form ionic alkaline earth metal halides.
- All the alkaline earth metals except beryllium also react with water to form strongly alkaline hydroxides which should be handled with great care.
- The heavier alkaline earth metals react more vigorously than the lighter ones.
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Microbial Growth at Low or High pH
- Solutions with a pH less than 7 are said to be acidic, and solutions with a pH greater than 7 are said to be basic or alkaline .
- Alkaliphiles are microbes that thrive in alkaline environments with a pH of 9 to 11, such as playa lakes and carbonate-rich soils.
- To survive, alkaliphiles maintain a relatively low alkaline level of about 8 pH inside their cells by constantly pumping hydrogen ions in the form of hydronium ions (H3O+) across their cell membranes and into their cytoplasm.
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Paget's Disease
- Because early diagnosis and treatment is important, after age 40, siblings and children of someone with Paget's disease may wish to have an alkaline phosphatase blood test every two or three years.
- If the alkaline phosphatase level is above normal, other tests such as a bone-specific alkaline phosphatase test, bone scan, or X-ray can be performed.
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Dry Cell Battery
- Another example of a dry-cell battery is the alkaline battery.
- Alkaline batteries are almost the same as zinc-carbon batteries, except that the electrolyte used is potassium hydroxide (KOH) rather than ammonium chloride.
- In some more modern types of so-called "high-power" batteries that have a much lower capacity than standard alkaline batteries, the ammonium chloride is replaced by zinc chloride.
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Alkalosis
- Alkalosis is the increased alkalinity of blood and other tissues, generally occurring when the blood pH is above 7.45.
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Other Rechargeable Batteries
- Different types include lead-acid, nickel-cadmium (NiCd), nickel-metal hydride (NiMH), lithium-ion (Li-ion), lithium-ion polymer (LiPo), and rechargeable alkaline batteries.
- There are also rechargeable forms of alkaline batteries, which are a type of primary battery dependent upon the reaction between zinc (Zn) and manganese dioxide (MnO2).
- Rechargeable alkaline batteries can also have a high recharging efficiency and have less environmental impact than disposable cells.
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Buffers Containing a Base and Conjugate Acid
- An alkaline buffer can be made from a mixture of the base and its conjugate acid, but the formulas for determining pH take a different form.
- An alkaline buffer can be made from a mixture of a base and its conjugate acid, similar to the way in which weak acids and their conjugate bases can be used to make a buffer.
- Calculate the pH of an alkaline buffer system consisting of a weak base and its conjugate acid.
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Histology of the Small Intestine
- The main function of these glands is to produce a mucus-rich alkaline secretion (containing bicarbonate) in order to neutralize the acidic content of chyme (which is introduced into the duodenum from the stomach), provide an alkaline condition for optimal intestinal enzyme activity, thus enabling absorption to take place, and lubricate the intestinal walls.
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The Arrhenius Definition
- The Arrhenius definitions of acidity and alkalinity are restricted to aqueous solutions and refer to the concentration of the solvated ions.
- In addition, under the Arrhenius definition, a solution of sodium amide (NaNH2) in liquid ammonia is not alkaline, despite the fact that the amide ion ($\text{NH}_2^-$) will readily deprotonate ammonia.
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Physical Characteristics of Urine
- Physical characteristics that can be applied to urine include color, turbidity (transparency), smell (odor), pH (acidity - alkalinity) and density.
- For example, high protein diets result in more acidic urine, but vegetarian diets generally result in more alkaline urine (both within the typical range of 4.6 - 8).