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pH

 
the negative logarithm of the hydrogen ion concentration, [H+], a measure of the degree to which a solution is acidic or alkaline. An acid is a substance that can give up a hydrogen ion (H+); a base is a substance that can accept H+. The more acidic a solution the greater the hydrogen ion concentration and the lower the pH; a pH of 7.0 indicates neutrality, a pH of less than 7 indicates acidity, and a pH of more than 7 indicates alkalinity. The pH is used as a measure of whether the body is maintaining a normal acid-base balance. A favorable pH is essential to the functioning of enzymes and other biochemical systems. The body's fluids are normally somewhat alkaline, the pH being between 7.35 and 7.45. A pH above 7.8 or below 6.8 is generally fatal. See also acidosis and alkalosis.
pH scale. From Applegate, 2000.

Ph

Symbol for phenyl.

pH

Symbol for the negative decadic logarithm of the H+ ion concentration (measured in moles per liter); a solution with pH 7.00 (1 × 10-7 g molecular weight of H+K per liter) is neutral at 22°C (that is, [H+] = [OH-]), one with a pH value of more than 7.00 is alkaline, one with a pH lower than 7.00 is acid. At 37°C, neutrality is at a pH value of 6.80. Compare: dissociation constant of water.
[p (power or potency) of [H+ ]]

PH

abbr.
1. penthouse
2. public health
3. Purple Heart

PH

Abbreviation for:
acidity (pH)
hydrogen ion concentration
papillary hyperplasia
parathyroid hormone
partial hysterectomy
passive haemagglutination
past history
patient history
peliosis hepatis
phaeochromocytoma
pharmacy
phenacetin
Philadelphia
phosphate
pin hole
porphyria hepatica
posterior hypothalamus
postural hypotension
primary hyperparathyroidism
prolyl hydroxylase
Prospect Hill
pseudoepitheliomatous hyperplasia
public health
pulmonary haemorrhage
pulmonary haemosiderosis
pulmonary hypertension

storage lesion

Transfusion medicine The constellation of changes occurring in a unit of packed red cells during storage. See Red cell preservatives.
Storage lesions
Ammonium to 470 µmol/L–US: 800 µg/dL
Free Hb in plasma from 82 to 6580 mg/L–US: 8.2 to 658 mg/dL
K+ from 4.2 to 78.5 mmol/L–US: 4.2 to 78.5 mEq/L
ATP from 100% to 45%
2,3 DPG to < 10% of original levels–replenished within 24 hours of transfusion
Labile proteins, eg complement, fibronectin and coagulation factors ↓ to negligible
Na+ from 169 to 111 mmol/L–US: 169 to 111 mEq/L
pH from 7.6 to 6.7
Adverse physiologic effects of stored blood is negligible in the absence of a previous compromise of the Pt's–recipient's status

Ph

Abbreviation for phenyl.

pH

Symbol for the negative logarithm of the H+ ion concentration (measured in moles per liter); a solution with pH 7.00 is neutral at 22°C, one with a pH of more than 7.0 is alkaline, and one with a pH lower than 7.00 is acid. At a temperature of 37°C, neutrality is at a pH value of 6.8.
[p (power or potency) of [H+]]

Ph

1. Pharmacopoeia.
2. Symbol for phenyl.

Enlarge picture
pH SCALE: Values of body fluids and some familiar solutions

pH

[Ger. Potenz, power + H, symbol for hydrogen]
In chemistry, a measure of the hydrogen ion concentration of a solution. The degree of acidity or alkalinity of a substance is expressed in a pH value. A solution that is neither acid nor alkaline has a pH of 7. Increasing acidity is expressed as a number less than 7, and increasing alkalinity as a number greater than 7. Maximum acidity is pH 0 and maximum alkalinity is pH 14. Because the pH scale is logarithmic, there is a 10-fold difference between each unit. For example, pH 5 is 10 times as acid as pH 6 and pH 4 is 100 times as acid as pH 6. The general mathematical formula defining pH is: pH = -log [H+], in which pH is the negative logarithm of the hydrogen ion concentration. The pH of a solution may be determined electrically by a pH meter or colorimetrically by the use of indicators. A list of indicators and the pH range registered by each is given under the indicator.
See: illustration; table; indicatorHCl—hydrochloric acid; NaOH—sodium hydroxide
MaterialpH
10% HCl 1.0
Gastric juice 1.0–5.0
0.1% HCl 3.0
Pure water (neutral) at 25°C 7.0
Blood plasma 7.35–7.45
Pancreatic juice 8.4–8.9
0.1% NaOH11.0
10% NaOH13.0

pH

An expression, widely used in medicine, of the acidity or alkalinity of a solution. pH is the logarithm to the base 10 of the concentration of free hydrogen ions in moles per litre, expressed as a positive number. The pH scale ranges from 0 to 14. Neutrality is 7. Figures below 7 indicate acidity, increasing towards zero; figures rising above 7 indicate increasing alkalinity. The pH of body fluids, in health, is accurately maintained between about 7.3 to 7.5. Below this range the condition of acidosis exists; above it, alkalosis. Both are dangerous.

pH

a measure of the hydrogen ion concentration in an aqueous solution. The formula is:

The formula produces a value in which the higher the number of H+ ions the lower the pH reading. The scale of pH values is from 1.0 (highly acid) to 14 (highly alkaline) with 7.0 as the neutral point. Since the pH is logarithmic, each change of one pH unit means a tenfold change in the number of hydrogen ions. pH can be measured by using indicators which change colour with changing pH, or by electrical means using a pH meter.

pH

A measurement of the acidity or alkalinity of a solution based on the amount of hydrogen ions available. Based on a scale of 14, a pH of 7.0 is neutral. A pH below 7.0 is an acid; the lower the number, the stronger the acid. A pH above 7.0 is a base; the higher the number, the stronger the base. Blood pH is slightly alkaline (basic) with a normal range of 7.36-7.44.

pH 

Symbol for the logarithm to base 10 of the reciprocal of the hydrogen (H) ion concentration measured in gram molecular weight in an aqueous solution. A solution with a pH 7.0 is neutral, one with a pH of more than 7.0 is alkaline, one with a pH lower than 7.0 is acid. It is a convenient way of expressing the acidity or alkalinity of solutions, particularly of contact lens buffer solutions. Alkaline ophthalmic solutions generally cause less discomfort than acidic ones. Note: pH stands for power (or potency) of H. See acidosis.
References in periodicals archive ?
Acidosis refers to a systemic pH of less than 7.35 on the 0-14 pH scale, while alkalosis means the systemic pH is above 7.45 on the same scale.
The term pH refers to the "power of Hydrogen" and the pH scale ranges from 0 to 14.
The pH scale indicates how acidic or basic a solution is by giving the concentration of hydrogen ions.
The pH scale is logarithmic, this means that a difference of one pH unit represents a tenfold change.
This pH scale for aqueous solutions and natural waters is a convenient range because it places the neutral value of pure water at 25 [degrees] C at 7.0--right in the middle, pH has been defined as -log aH+, where aH+ = gH+ mH+ or the activity of the hydrogen atom.
The pH scale ranges from 1 to 14: One to 6.5 is acidic, 7.5 to 14 is heavy with alkaline, and 7 indicates soil that is neither overly acidic or base.
Soil acidity should stay around 5 on a pH scale, to keep the rots from developing."
You can buy a soil-testing kit that measures acidity according to the pH scale. Neutral soil is pH7.
The students wrestled with the pH scale of acids and bases in the "Acid Rain" unit.
The pH scale can determine presence of additional contaminants which are not detected by halogenide testing (such as sulfates and nitrates), and can corroborate halogenide surface concentrations measured.
As well, the discharge must fall between 6.0 and 9.5 on the pH scale.
Think of the pH scale as a "Richter Scale of Acidity," but without the openendedness of the earthquake scale.