Sodium thiocyanate is the chemical compound with the formula NaSCN. This colorless deliquescent salt is one of the main sources of the thiocyanate anion; as such, it is used as a precursor for the synthesis of pharmaceuticals and other specialty chemicals. Thiocyanate salts are prepared by the reaction of cyanide with elemental sulfur: 8 NaCN + S8 → 8 NaSCNSodium thiocyanate crystallizes in an orthorhombic cell; each Na+ center is surrounded by three sulfur and three nitrogen ligands provided by the triatomic thiocyanate anion. It is used in the laboratory as a test for the presence of Fe3+ ions. Sodium thiocyanate is employed to convert alkyl halides into the corresponding alkylthiocyanates. Related reagents include ammonium thiocyanate and potassium thiocyanate, which has twice the solubility in water. Silver thiocyanate may be used as well. Treatment of isopropyl bromide with sodium thiocyanate in a hot ethanolic solution affords isopropyl thiocyanate. Protonation of sodium thiocyanate affords isothiocyanic acid, S=C=NH.
This species is generated in situ from sodium thiocyanate.
An electrolyte is a substance that produces an electrically conducting solution when dissolved in a polar solvent, such as water. The dissolved electrolyte separates into cations and anions, which disperse uniformly through the solvent. Electrically, such a solution is neutral. If an electric potential is applied to such a solution, the cations of the solution are drawn to the electrode that has an abundance of electrons, while the anions are drawn to the electrode that has a deficit of electrons; the movement of anions and cations in opposite directions within the solution amounts to a current. This includes most soluble salts and bases; some gases, such as hydrogen chloride, under conditions of high temperature or low pressure can function as electrolytes. Electrolyte solutions can result from the dissolution of some biological and synthetic polymers, termed "polyelectrolytes", which contain charged functional groups. A substance that dissociates into ions in solution acquires the capacity to conduct electricity.
Sodium, chloride, calcium and phosphate are examples of electrolytes. In medicine, electrolyte replacement is needed when a person has prolonged vomiting or diarrhea, as a response to strenuous athletic activity. Commercial electrolyte solutions are available for sick children and athletes. Electrolyte monitoring is important in the treatment of bulimia; the word electrolyte derives from the Greek lytós, meaning "able to be untied or loosened". Svante Arrhenius put forth, in his 1884 dissertation, his explanation of the fact that solid crystalline salts disassociate into paired charged particles when dissolved, for which he won the 1903 Nobel Prize in Chemistry. Arrhenius's explanation was that in forming a solution, the salt dissociates into charged particles, to which Michael Faraday had given the name "ions" many years earlier. Faraday's belief had been. Arrhenius proposed that in the absence of an electric current, solutions of salts contained ions, he thus proposed. Electrolyte solutions are formed when a salt is placed into a solvent such as water and the individual components dissociate due to the thermodynamic interactions between solvent and solute molecules, in a process called "solvation".
For example, when table salt, NaCl, is placed in water, the salt dissolves into its component ions, according to the dissociation reaction NaCl → Na+ + Cl−It is possible for substances to react with water, producing ions. For example, carbon dioxide gas dissolves in water to produce a solution that contains hydronium and hydrogen carbonate ions. Molten salts can be electrolytes as, for example, when sodium chloride is molten, the liquid conducts electricity. In particular, ionic liquids, which are molten salts with melting points below 100 °C, are a type of conductive non-aqueous electrolytes and thus have found more and more applications in fuel cells and batteries. An electrolyte in a solution may be described as "concentrated" if it has a high concentration of ions, or "diluted" if it has a low concentration. If a high proportion of the solute dissociates to form free ions, the electrolyte is strong; the properties of electrolytes may be exploited using electrolysis to extract constituent elements and compounds contained within the solution.
Alkaline earth metals form hydroxides that are strong electrolytes with limited solubility in water, due to the strong attraction between their constituent ions. This limits their application to situations. In physiology, the primary ions of electrolytes are sodium, calcium, chloride, hydrogen phosphate, hydrogen carbonate; the electric charge symbols of plus and minus indicate that the substance is ionic in nature and has an imbalanced distribution of electrons, the result of chemical dissociation. Sodium is the main electrolyte found in extracellular fluid and potassium is the main intracellular electrolyte. All known higher lifeforms require a subtle and complex electrolyte balance between the intracellular and extracellular environments. In particular, the maintenance of precise osmotic gradients of electrolytes is important; such gradients affect and regulate the hydration of the body as well as blood pH, are critical for nerve and muscle function. Various mechanisms exist in living species that keep the concentrations of different electrolytes under tight control.
Both muscle tissue and neurons are considered electric tissues of the body. Muscles and neurons are activated by electrolyte activity between the extracellular fluid or interstitial fluid, intracellular fluid. Electrolytes may enter or leave the cell membrane through specialized protein structures embedded in the plasma membrane called "ion channels". For example, muscle contraction is dependent upon the presence of calcium and potassium. Without sufficient levels of these key electrolytes, muscle weakness or severe muscle contractions may occur. Electrolyte balance is maintained by oral, or in emergencies, intravenous intake of electrolyte-containing substances, is regulated by hormones, in general with the kidneys flushing out excess levels. In humans, electrolyte homeostasis is regulated by hormones such as antidiuretic hormones and parathyroid hormones. Serious electrol
Nickel chloride, is the chemical compound NiCl2. The anhydrous salt is yellow. Nickel chloride, in various forms, is the most important source of nickel for chemical synthesis; the nickel chlorides are deliquescent. Nickel salts have been shown to be carcinogenic to the lungs and nasal passages in cases of long-term inhalation exposure; the largest scale production of nickel chloride involves the extraction with hydrochloric acid of nickel matte and residues obtained from roasting refining nickel-containing ores. Nickel chloride is not prepared in the laboratory because it is inexpensive and has a long shelf-life. Heating the hexahydrate in the range 66-133.°C gives the yellowish dihydrate, NiCl2·2H2O. The hydrates convert to the anhydrous form upon heating in thionyl chloride or by heating under a stream of HCl gas. Heating the hydrates does not afford the anhydrous dichloride. NiCl 2 ⋅ 6 H 2 O + 6 SOCl 2 ⟶ NiCl 2 + 6 SO 2 + 12 HCl The dehydration is accompanied by a color change from green to yellow.
In case one needs a pure compound without presence of cobalt, nickel chloride can be obtained cautiously heating hexammine nickel chloride: Cl 2 hexammine nickel chloride → 175 − 200 ∘ C NiCl 2 + 6 NH 3 NiCl2 adopts the CdCl2 structure. In this motif, each Ni2+ center is coordinated to six Cl− centers, each chloride is bonded to three Ni centers. In NiCl2 the Ni-Cl bonds have "ionic character". Yellow NiBr2 and black NiI2 adopt similar structures, but with a different packing of the halides, adopting the CdI2 motif. In contrast, NiCl2·6H2O consists of separated trans- molecules linked more weakly to adjacent water molecules. Only four of the six water molecules in the formula is bound to the nickel, the remaining two are water of crystallization. Cobalt chloride hexahydrate has a similar structure; the hexahydrate occurs in nature as the rare mineral nickelbischofite. The dihydrate NiCl2·2H2O adopts a structure intermediate between the hexahydrate and the anhydrous forms, it consists of infinite chains of NiCl2.
The trans sites on the octahedral centers occupied by aquo ligands. A tetrahydrate NiCl2·4H2O is known. Nickel chloride solutions are acidic, with a pH of around 4 due to the hydrolysis of the Ni2+ ion. Most of the reactions ascribed to "nickel chloride" involve the hexahydrate, although specialized reactions require the anhydrous form. Reactions starting from NiCl2·6H2O can be used to form a variety of nickel coordination complexes because the H2O ligands are displaced by ammonia, thioethers and organophosphines. In some derivatives, the chloride remains within the coordination sphere, whereas chloride is displaced with basic ligands. Illustrative complexes include: Some nickel chloride complexes exist as an equilibrium mixture of two geometries. For example, NiCl22, containing four-coordinate Ni, exists in solution as a mixture of both the diamagnetic square planar and the paramagnetic tetrahedral isomers. Square planar complexes of nickel can form five-coordinate adducts. NiCl2 is the precursor to acetylacetonate complexes Ni22 and the benzene-soluble 3, a precursor to Ni2, an important reagent in organonickel chemistry.
In the presence of water scavengers, hydrated nickel chloride reacts with dimethoxyethane to form the molecular complex NiCl22. The dme ligands in this complex are labile. For example, this complex reacts with sodium cyclopentadienide to give the sandwich compound nickelocene. Hexammine nickel chloride complex is soluble when respective cobalt complex is not, which allows for easy separating of these close-related metals in laboratory conditions. NiCl2 and its hydrate are useful in organic synthesis; as a mild Lewis acid, e.g. for the regioselective isomerization of dienols:In combination with CrCl2 for the coupling of an aldehyde and a vinylic iodide to give allylic alcohols. For selective reductions in the presence of LiAlH4, e.g. for the conversion of alkenes to alkanes. As a precursor to nickel boride, prepared in situ from NiCl2 and NaBH4; this reagent behaves like Raney Nickel, comprising an efficient system for hydrogenation of unsaturated carbonyl compounds. As a precursor to finely divided Ni by reduction with Zn, for the reduction of aldehydes and nitro aromatic compounds.
This reagent promotes homo-coupling reactions, 2RX → R-R where R = aryl, vinyl. As a catalyst for making dialkyl arylphosphonates from phosphites and aryl iodide, ArI:ArI + P3 → ArP2 + EtINiCl2-dme is used due to its increased solubility in comparis
Nickel sulfate, or just nickel sulfate refers to the inorganic compound with the formula NiSO46. This soluble blue-coloured salt is a common source of the Ni2+ ion for electroplating. 40,000 tonnes were produced in 2005. It is used for electroplating of nickel. In 2005–06, nickel sulfate was the top allergen in patch tests. At least seven sulfate salts of nickel are known; these salts differ in terms of their crystal habit. The common tetragonal hexahydrate crystallizes from aqueous solution between 30.7 and 53.8 °C. Below these temperatures, a heptahydrate crystallises, above these temperatures an orthorhombic hexahydrate forms; the yellow anhydrous form, NiSO4, is a high melting solid, encountered in the laboratory. This material is produced by heating the hydrates above 330 °C, it decomposes at still higher temperatures to nickel oxide. X-ray crystallography measurements show; these ions in turn are hydrogen bonded to sulfate ions. Dissolution of the salt in water gives solutions containing the aquo complex 2+.
All nickel sulfates are paramagnetic. The salt is obtained as a by-product of copper refining, it is produced by dissolution of nickel metal or nickel oxides in sulfuric acid. Aqueous solutions of nickel sulfate reacts with sodium carbonate to precipitate nickel carbonate, a precursor to nickel-based catalysts and pigments. Addition of ammonium sulfate to concentrated aqueous solutions of nickel sulfate precipitates Ni22·6H2O; this blue-coloured solid is analogous to Mohr's salt, Fe22·6H2O. Nickel sulfate is used in the laboratory. Columns used in polyhistidine-tagging, useful in biochemistry and molecular biology, are regenerated with nickel sulfate. Aqueous solutions of NiSO4·6H2O and related hydrates react with ammonia to give SO4 and with ethylenediamine to give SO4; the latter is used as a calibrant for magnetic susceptibility measurements because it has no tendency to hydrate. Nickel sulfate occurs as the rare mineral retgersite, a hexahydrate; the second hexahydrate is known as nickel hexahydrite SO4·6H2O.
The heptahydrate, unstable in air, occurs as morenosite. The monohydrate occurs as rare mineral dwornikite SO4·H2O. In 2005–06, nickel sulfate was the top allergen in patch tests. Nickel sulfate is classified as a human carcinogen based on increased respiratory cancer risks observed in epidemiological studies of sulfidic ore refinery workers. In a 2-year inhalation study in F344 rats and B6C3F1 mice, there was no evidence of carcinogenic activity, although increased lung inflammations and bronchial lymph node hyperplasia were observed; these results suggest that there is a threshold for the carcinogenicity of nickel sulfate via inhalation. In a 2-year study with daily oral administration of nickel sulfate hexahydrate to F344 rats, no evidence for increased carcinogenic activity was observed; the human and animal data indicate a lack of carcinogenicity via the oral route of exposure and limit the carcinogenicity of nickel compounds to respiratory tumours after inhalation. Whether these effects are relevant to humans is unclear as epidemiological studies of exposed female workers have not shown adverse developmental toxicity effects.
International Chemical Safety Card 0063
A cathode is the electrode from which a conventional current leaves a polarized electrical device. This definition can be recalled by using the mnemonic CCD for Cathode Current Departs. A conventional current describes the direction. Electrons have a negative electrical charge, so the movement of electrons is opposite to that of the conventional current flow; the mnemonic cathode current departs means that electrons flow into the device's cathode from the external circuit. The electrode through which conventional current flows the other way, into the device, is termed an anode. Conventional current flow is from cathode to anode outside of the cell or device, regardless of the cell or device type and operating mode. Cathode polarity with respect to the anode can be positive or negative depending on how the device is being operated. Although positively charged cations always move towards the cathode and negatively charged anions move away from it, cathode polarity depends on the device type, can vary according to the operating mode.
In a device which absorbs energy of charge, the cathode is negative, in a device which provides energy, the cathode is positive: A battery or galvanic cell in use has a cathode, the positive terminal since, where the current flows out of the device. This outward current is carried internally by positive ions moving from the electrolyte to the positive cathode, it is continued externally by electrons moving into the battery which constitutes positive current flowing outwards. For example, the Daniell galvanic cell's copper electrode is the cathode. A battery, recharging or an electrolytic cell performing electrolysis has its cathode as the negative terminal, from which current exits the device and returns to the external generator as charge enters the battery/ cell. For example, reversing the current direction in a Daniell galvanic cell converts it into an electrolytic cell where the copper electrode is the positive terminal and the anode. In a diode, the cathode is the negative terminal at the pointed end of the arrow symbol, where current flows out of the device.
Note: electrode naming for diodes is always based on the direction of the forward current for types such as Zener diodes or solar cells where the current of interest is the reverse current. In vacuum tubes it is the negative terminal where electrons enter the device from the external circuit and proceed into the tube's near-vacuum, constituting a positive current flowing out of the device; the word was coined in 1834 from the Greek κάθοδος,'descent' or'way down', by William Whewell, consulted by Michael Faraday over some new names needed to complete a paper on the discovered process of electrolysis. In that paper Faraday explained that when an electrolytic cell is oriented so that electric current traverses the "decomposing body" in a direction "from East to West, or, which will strengthen this help to the memory, that in which the sun appears to move", the cathode is where the current leaves the electrolyte, on the West side: "kata downwards, `odos a way; the use of'West' to mean the'out' direction may appear unnecessarily contrived.
As related in the first reference cited above, Faraday had used the more straightforward term "exode". His motivation for changing it to something meaning'the West electrode' was to make it immune to a possible change in the direction convention for current, whose exact nature was not known at the time; the reference he used to this effect was the Earth's magnetic field direction, which at that time was believed to be invariant. He fundamentally defined his arbitrary orientation for the cell as being that in which the internal current would run parallel to and in the same direction as a hypothetical magnetizing current loop around the local line of latitude which would induce a magnetic dipole field oriented like the Earth's; this made the internal current East to West as mentioned, but in the event of a convention change it would have become West to East, so that the West electrode would not have been the'way out' any more. Therefore, "exode" would have become inappropriate, whereas "cathode" meaning'West electrode' would have remained correct with respect to the unchanged direction of the actual phenomenon underlying the current unknown but, he thought, unambiguously defined by the magnetic reference.
In retrospect the name change was unfortunate, not only because the Greek roots alone do not reveal the cathode's function any more, but more because, as we now know, the Earth's magnetic field direction on which the "cathode" term is based is subject to reversals whereas the current direction convention on which the "exode" term was based has no reason to change in the future. Since the discovery of the electron, an easier to remember, more durably technically correct, etymology has been suggested: cathode, from the Greek kathodos,'way down','the way into the cell for electrons'. In chemistry, a cathode is the electrode of an electrochemical cell.
A plumbing fixture is an exchangeable device which can be connected to a plumbing system to deliver and drain water. The most common plumbing fixtures are: Bathtubs Bidets Channel drains Drinking fountains Hose bib Janitor sinks Kitchen sinks Showers Pipes Tapware - an industry term for that sub-category of plumbing fixtures consisting of tap valves called water taps or faucets, their accessories, such as water spouts and shower heads. Terminal valves for dishwashers, ice makers, etc. Urinals Utility sinks Flush toilets Each of these plumbing fixtures has one or more water outlets and a drain. In some cases, the drain has a device that can be manipulated to block the drain to fill the basin of the fixture; each fixture has a flood rim, or level at which water will begin to overflow. Most fixtures have an overflow, a conduit for water to drain away, when the regular drain is plugged, before the water overflows at the flood rim level. However, water closets and showers lack this feature because their drains cannot be stopped.
Each fixture has a characteristic means of connection. Normal plumbing practice is to install a valve on each water supply line before the fixture, this is most termed a stop or "service valve"; the water supply to some fixtures is cold water only. Most fixtures have a hot water supply. In some occasional cases, a sink may have both a non-potable water supply. Lavatories and water closets connect to the water supply by means of a supply, a tube of nominal 3/8 in or 10 or 12 mm diameter, which connects the water supply to the fixture, sometimes through a flexible hose. For water closets, this tube ends in a flat neoprene washer that tightens against the connection, while for lavatories, the supply ends in a conical neoprene washer. Kitchen sinks and showers have supply tubes built onto their valves which are soldered or'fast jointed' directly onto the water supply pipes; the actual initial drain part in a lavatory or sink is termed a strainer. If there is a removable strainer device that fits into the fixed strainer, it is termed a strainer basket.
The initial pipe that leads from the strainer to the trap is termed the tailpiece. Floor-mounted water closets seal to the toilet flange of the drain pipe by means of a wax ring; these are traditionally made out of beeswax. However, their proper sealing depends on proper seating of the water closet, on a firm and secure base, on proper installation of the closet bolts which secure the closet to the flange, in turn supposed to be securely fastened to the floor. All plumbing fixtures have traps in their drains. Traps are pipes which curve down back up; this prevents sewer gas from entering buildings. Most water closets and many urinals have the trap integral with the fixture itself; the visible water surface in a toilet is the top of the trap's water seal. Each fixture drain, with exceptions, must be vented so that negative air pressure in the drain cannot siphon the trap dry, to prevent positive air pressure in the sewer from forcing gases past the water seal, to prevent explosive sewer gas buildup.
The garbage disposal was invented in 1927 by architect John Hammes of Racine, WI. He went on to found InSinkErator a year; the function of the garbage disposer is to grind food waste so that it can be sent down standard household plumbing without clogging. The device works by attaching a small chamber underneath the drain of a sink; this chamber contains whirling blades and grinders which chop and grind the waste into much smaller particles. Once the food is small enough to pass out of this chamber, it is flushed down the rest of the plumbing. In most of Europe, garbage disposers are not used at all. Instead, garbage is separated at the source, into compostable and other types of garbage and collected. In the United States there have been some political and environmental issues with garbage disposers. For many years, New York City had banned their use; the stated reason was the above-mentioned increased sewage treatment capacity, but many area residents suspected that it was the garbage unions not wanting work taken away from them.
The ban was rescinded on September 11, 1997. In public facilities, the trend is toward sensor-operated fixtures that improve hygiene and save money. For example, sensor operated automatic-flush urinals have fewer moving parts, reduce wear, tend to last longer than manual-flush valves, they ensure fixtures are flushed only once per use. Some contain intelligence that flushes them at different amounts of water flow depending on traffic patterns: e.g. the fixture can detect a lineup of users and only give a full flush after the last person has used the urinal. For the same purpose, dual-flush toilets are becoming more popular. A combination of both technologies can allow for saved water. Automatic flush compensates for users. Since the fixtures are always flushed, there is no need for a urinal cake, or other odor reduction. Sensor-operated toilets al
Chrome plating referred to as chrome, is a technique of electroplating a thin layer of chromium onto a metal object. The chromed layer can be decorative, provide corrosion resistance, ease cleaning procedures, or increase surface hardness. Sometimes, a less expensive imitator of chrome may be used for aesthetic purposes. Chrome plating a component includes these stages: Degreasing to remove heavy soiling Manual cleaning to remove all residual traces of dirt and surface impurities Various pretreatments depending on the substrate Placement into the chrome plating vat, where it is allowed to warm to solution temperature Application of plating current for the required time to attain the desired thicknessThere are many variations to this process, depending on the type of substrate being plated. Different substrates need different etching solutions, such as hydrochloric and sulfuric acids. Ferric chloride is popular for the etching of nimonic alloys. Sometimes the component enters the chrome plating vat.
Sometimes the component has a conforming anode made from platinized titanium. A typical hard chrome vat plates at about 1 mil per hour. Various finishing and buffing processes are used in preparing components for decorative chrome plating; the chrome plating chemicals are toxic. Disposal of chemicals is regulated in most countries; some common industry specifications governing the chrome plating process are AMS 2460, AMS 2406, MIL-STD-1501. Hexavalent chromium plating known as hex-chrome, Cr6+, chrome plating, uses chromium trioxide as the main ingredient. Hexavalent chromium plating solution is used for decorative and hard plating, along with bright dipping of copper alloys, chromic acid anodizing, chromate conversion coating. A typical hexavalent chromium plating process is: activation bath, chromium bath and rinse; the activation bath is a tank of chromic acid with a reverse current run through it. This removes any scale. In some cases the activation step is done in the chromium bath; the chromium bath is a mixture of chromium trioxide and sulfuric acid, the ratio of which varies between 75:1 to 250:1 by weight.
This results in an acidic bath. The temperature and current density in the bath affect final coverage. For decorative coating the temperature ranges from 35 to 45 °C, but for hard coating it ranges from 50 to 65 °C. Temperature is dependent on the current density, because a higher current density requires a higher temperature; the whole bath is agitated to keep the temperature steady and achieve a uniform deposition. One functional disadvantage of hexavalent chromium plating is low cathode efficiency, which results in bad throwing power; this means it leaves a non-uniform coating, with less in inside corners and holes. To overcome this problem the part may be over-plated and ground to size, or auxiliary anodes may be used around the hard-to-plate areas. From a health standpoint, hexavalent chromium is the most toxic form of chromium. In the U. S. the Environmental Protection Agency regulates it heavily. The EPA lists hexavalent chromium as a hazardous air pollutant because it is a human carcinogen, a "priority pollutant" under the Clean Water Act, a "hazardous constituent" under the Resource Conservation and Recovery Act.
Due to its low cathodic efficiency and high solution viscosity, a toxic mist of water and hexavalent chromium is released from the bath. Wet scrubbers are used to control these emissions; the discharge from the wet scrubbers is treated to precipitate the chromium from the solution because it cannot remain in the waste water. Maintaining a bath surface tension less than 35 dynes/cm requires a frequent cycle of treating the bath with a wetting agent and confirming the effect on surface tension. Traditionally, surface tension is measured with a stalagmometer; this method is, however and suffers from inaccuracy, is dependent on the user's experience and capabilities. Additional toxic waste created from hexavalent chromium baths include lead chromates, which form in the bath because lead anodes are used. Barium is used to control the sulfate concentration, which leads to the formation of barium sulfate, a hazardous waste. Trivalent chromium plating known as tri-chrome, Cr3+, chrome plating, uses chromium sulfate or chromium chloride as the main ingredient.
Trivalent chromium plating is an alternative to hexavalent chromium in certain applications and thicknesses. A trivalent chromium plating process is similar to the hexavalent chromium plating process, except for the bath chemistry and anode composition. There are three main types of trivalent chromium bath configurations: A chloride- or sulfate-based electrolyte bath using graphite or composite anodes, plus additives to prevent the oxidation of trivalent chromium to the anodes. A sulfate-based bath that uses lead anodes surrounded by boxes filled with sulfuric acid, which keeps the trivalent chromium from oxidizing at the anodes. A sulfate-based bath that uses insoluble catalytic anodes, which maintains an electrode potential that prevents oxidation; the trivalent chromium-plating process can plate the workpieces at a similar temperature and hardness, as compared to hexavalent chromium. Plating thickness ranges from 0.005 to 0.05 mils. The functional advantages of trivalent chromium are higher cathode efficiency and better throwing power.
Better throwing power means better production