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PH Scale 3
In chemistry, pH (), historically denoting "potential of hydrogen" (or "power of hydrogen"), is a scale used to specify the acidity or basicity of an aqueous solution. Acidic solutions (solutions with higher concentrations of ions) are measured to have lower pH values than basic or alkaline solutions. The pH scale is logarithmic and inversely indicates the concentration of hydrogen ions in the solution.Bates, Roger G. ''Determination of pH: theory and practice''. Wiley, 1973. :\ce = - \log(a_\ce) = -\log( ce\ce M) where M = mol dm−3. At 25 °C (77 °F), solutions with a pH less than 7 are acidic, and solutions with a pH greater than 7 are basic. Solutions with a pH of 7 at this temperature are neutral (i.e. have the same concentration of H+ ions as OH− ions, i.e. pure water). The neutral value of the pH depends on the temperaturebeing lower than 7 if the temperature increases above 25 °C. The pH value can be less than 0 for very concentrated strong ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Glass Electrode
A glass electrode is a type of ion-selective electrode made of a doped glass membrane that is sensitive to a specific ion. The most common application of ion-selective glass electrodes is for the measurement of pH. The pH electrode is an example of a glass electrode that is sensitive to hydrogen ions. Glass electrodes play an important part in the instrumentation for chemical analysis and physicochemical studies. The voltage of the glass electrode, relative to some reference value, is sensitive to changes in the activity of a certain type of ions. History The first studies of glass electrodes (GE) found different sensitivities of different glasses to change the medium's acidity (pH), due to the effects of the alkali metal ions. In 1906, M. Cremer, the father of Erika Cremer, determined that the electric potential that arises between parts of the fluid, located on opposite sides of the glass membrane is proportional to the concentration of acid (hydrogen ion concentratio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
PH Meter
A pH meter is a scientific instrument that measures the hydrogen-ion activity in water-based solutions, indicating its acidity or alkalinity expressed as pH. The pH meter measures the difference in electrical potential between a pH electrode and a reference electrode, and so the pH meter is sometimes referred to as a "potentiometric pH meter". The difference in electrical potential relates to the acidity or pH of the solution. Testing of pH via pH meters (pH-metry) is used in many applications ranging from laboratory experimentation to quality control. Applications The rate and outcome of chemical reactions taking place in water often depends on the acidity of the water, and it is therefore useful to know the acidity of the water, typically measured by means of a pH meter. Knowledge of pH is useful or critical in many situations, including chemical laboratory analyses. pH meters are used for soil measurements in agriculture, water quality for municipal water supplies, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
PH Indicator
A pH indicator is a halochromic chemical compound added in small amounts to a solution so the pH (acidity or basicity) of the solution can be determined visually or spectroscopically by changes in absorption and/or emission properties. Hence, a pH indicator is a chemical detector for hydronium ions (H3O+) or hydrogen ions (H+) in the Arrhenius model. Normally, the indicator causes the color of the solution to change depending on the pH. Indicators can also show change in other physical properties; for example, olfactory indicators show change in their odor. The pH value of a neutral solution is 7.0 at 25°C ( standard laboratory conditions). Solutions with a pH value below 7.0 are considered acidic and solutions with pH value above 7.0 are basic. Since most naturally occurring organic compounds are weak electrolytes, such as carboxylic acids and amines, pH indicators find many applications in biology and analytical chemistry. Moreover, pH indicators form one of the three ma ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Measurement Traceability
Traceability is the capability to trace something. In some cases, it is interpreted as the ability to verify the history, location, or application of an item by means of documented recorded identification. Other common definitions include the capability (and implementation) of keeping track of a given set or type of information to a given degree, or the ability to chronologically interrelate uniquely identifiable entities in a way that is verifiable. Traceability is applicable to measurement, supply chain, software development, healthcare and security. Measurement The term ''measurement traceability'' is used to refer to an unbroken chain of comparisons relating an instrument's measurements to a known standard. Calibration to a traceable standard can be used to determine an instrument's bias, precision, and accuracy. It may also be used to show a chain of custody - from current interpretation of evidence to the actual evidence in a legal context, or history of handling of any inf ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Base (chemistry)
In chemistry, there are three definitions in common use of the word base, known as Arrhenius bases, Brønsted bases, and Lewis bases. All definitions agree that bases are substances that react with acids, as originally proposed by G.-F. Rouelle in the mid-18th century. In 1884, Svante Arrhenius proposed that a base is a substance which dissociates in aqueous solution to form Hydroxide ions OH−. These ions can react with hydrogen ions (H+ according to Arrhenius) from the dissociation of acids to form water in an acid–base reaction. A base was therefore a metal hydroxide such as NaOH or Ca(OH)2. Such aqueous hydroxide solutions were also described by certain characteristic properties. They are slippery to the touch, can taste bitter and change the color of pH indicators (e.g., turn red litmus paper blue). In water, by altering the autoionization equilibrium, bases yield solutions in which the hydrogen ion activity is lower than it is in pure water, i.e., the water ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aqueous Solution
An aqueous solution is a solution in which the solvent is water. It is mostly shown in chemical equations by appending (aq) to the relevant chemical formula. For example, a solution of table salt, or sodium chloride (NaCl), in water would be represented as . The word ''aqueous'' (which comes from ''aqua'') means pertaining to, related to, similar to, or dissolved in, water. As water is an excellent solvent and is also naturally abundant, it is a ubiquitous solvent in chemistry. Since water is frequently used as the solvent in experiments, the word solution refers to an aqueous solution, unless the solvent is specified. A ''non-aqueous solution'' is a solution in which the solvent is a liquid, but is not water. (See also Solvent and Inorganic nonaqueous solvent.) Characteristics Substances that are ''hydrophobic'' ('water-fearing') do not dissolve well in water, whereas those that are ''hydrophilic'' ('water-friendly') do. An example of a hydrophilic substance is sodium chl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Silver Chloride Electrode
A silver chloride electrode is a type of reference electrode, commonly used in electrochemical measurements. For environmental reasons it has widely replaced the saturated calomel electrode. For example, it is usually the internal reference electrode in pH meters and it is often used as reference in reduction potential measurements. As an example of the latter, the silver chloride electrode is the most commonly used reference electrode for testing cathodic protection corrosion control systems in sea water environments. The electrode functions as a reversible redox electrode and the equilibrium is between the solid (s) silver metal (Ag(s)) and its solid salt— silver chloride (AgCl(s), also called silver(I) chloride) in a chloride solution of a given concentration. In electrochemical cell notation, the silver chloride electrode is written as, ''e.g.'', for an electrolyte solution of KCl 3 M: : \ , \ \ , \ KCl \ (3M) The corresponding half-reactions can be presented ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
German Language
German ( ) is a West Germanic language mainly spoken in Central Europe. It is the most widely spoken and official or co-official language in Germany, Austria, Switzerland, Liechtenstein, and the Italian province of South Tyrol. It is also a co-official language of Luxembourg and Belgium, as well as a national language in Namibia. Outside Germany, it is also spoken by German communities in France ( Bas-Rhin), Czech Republic ( North Bohemia), Poland (Upper Silesia), Slovakia ( Bratislava Region), and Hungary (Sopron). German is most similar to other languages within the West Germanic language branch, including Afrikaans, Dutch, English, the Frisian languages, Low German, Luxembourgish, Scots, and Yiddish. It also contains close similarities in vocabulary to some languages in the North Germanic group, such as Danish, Norwegian, and Swedish. German is the second most widely spoken Germanic language after English, which is also a West Germanic language. Germ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
French Language
French ( or ) is a Romance languages, Romance language of the Indo-European languages, Indo-European family. It descended from the Vulgar Latin of the Roman Empire, as did all Romance languages. French evolved from Gallo-Romance, the Latin spoken in Gaul, and more specifically in Northern Gaul. Its closest relatives are the other langues d'oïl—languages historically spoken in northern France and in southern Belgium, which French (Francien) largely supplanted. French was also substratum, influenced by native Celtic languages of Northern Roman Gaul like Gallia Belgica and by the (Germanic languages, Germanic) Frankish language of the post-Roman Franks, Frankish invaders. Today, owing to France's French colonial empire, past overseas expansion, there are numerous French-based creole languages, most notably Haitian Creole language, Haitian Creole. A French-speaking person or nation may be referred to as Francophone in both English and French. French is an official language in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Equivalent Concentration
In chemistry, the equivalent concentration or normality (N) of a solution is defined as the molar concentration ''ci'' divided by an equivalence factor ''f''eq: :Normality = Definition Normality is defined as the number of gramme or mole equivalents of solute present in one litre of solution. The SI unit of normality is Eq/L. Normality formula :Normality (N) = Weight of Solute (in gm) / (Equivalent Weight of Solute × Volume of the Solution (in liters))https://clavick.com/normality/ Usage There are three common types of chemical reaction where normality is used as a measure of reactive species in solution: *In acid-base chemistry, normality is used to express the concentration of hydronium ions (H3O+) or hydroxide ions (OH−) in a solution. Here, is an integer value. Each solute can produce one or more equivalents of reactive species when dissolved. *In redox reactions, the equivalence factor describes the number of electrons that an oxidizing or reducing agent c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Common Logarithm
In mathematics, the common logarithm is the logarithm with base 10. It is also known as the decadic logarithm and as the decimal logarithm, named after its base, or Briggsian logarithm, after Henry Briggs, an English mathematician who pioneered its use, as well as standard logarithm. Historically, it was known as ''logarithmus decimalis'' or ''logarithmus decadis''. It is indicated by , , or sometimes with a capital (however, this notation is ambiguous, since it can also mean the complex natural logarithmic multi-valued function). On calculators, it is printed as "log", but mathematicians usually mean natural logarithm (logarithm with base e ≈ 2.71828) rather than common logarithm when they write "log". To mitigate this ambiguity, the ISO 80000 specification recommends that should be written , and should be . Before the early 1970s, handheld electronic calculators were not available, and mechanical calculators capable of multiplication were bulky, expensive and not wide ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
