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The drive remains operable during the test. [110] There is a dedicated log for background scan results, separate from the self-test log. Offline data collection ATA drives may support a periodic short operation called "offline data collection". Although this feature is marked "obsolete", many modern hard drives retain this feature.
Beckman Model M pH Meter, 1937 [1] Beckman model 72 pH meter, 1960 781 pH/Ion Meter pH meter by Metrohm. 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. [2]
In and of themselves, pH indicators are usually weak acids or weak bases. The general reaction scheme of acidic pH indicators in aqueous solutions can be formulated as: HInd (aq) + H 2 O (l) ⇌ H 3 O + (aq) + Ind − (aq) where, "HInd" is the acidic form and "Ind −" is the conjugate base of the indicator. Vice versa for basic pH indicators ...
To prepare a solution for use as pH indicator, dissolve 0.10 g in 8.0 cm 3 N/50 (a.k.a. 0.02 Normal) NaOH and dilute with water to 250 cm 3. To prepare a solution for use as indicator in volumetric work, dissolve 0.1 g in 100 cm 3 of 50% (v/v) ethanol .
The pH range is commonly given as zero to 14, but a pH value can be less than 0 for very concentrated strong acids or greater than 14 for very concentrated strong bases. [2] The pH scale is traceable to a set of standard solutions whose pH is established by international agreement. [3]
Initially all external storage, tape and hard disk drives are today available as both internal and external storage. In the 1964 removable disk media was introduced by the IBM 2310 disk drive with its 2315 cartridge used in IBM 1800 and IBM 1130 computers. [ 7 ]
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A universal indicator is a pH indicator made of a solution of several compounds that exhibit various smooth colour changes over a wide range pH values to indicate the acidity or alkalinity of solutions. A universal indicator can be in paper form or present in a form of a solution. [1]