Potassium thiocyanate KSCN

To use KBr discs for quantitative measurements it is best to employ an internal standard procedure in which a substance possessing a prominent isolated infrared absorption band is mixed with the potassium bromide. The substance most commonly used is potassium thiocyanate, KSCN, which is intimately mixed and ground to give a uniform concentration, usually 0.1-0.2 per cent, in the potassium bromide. A KBr/KSCN disc will give a characteristic absorption band at 2125 cm 1. Before quantitative measurements can be carried out it is necessary to prepare a calibration curve from a series of standards made using different amounts of the pure organic compound with the KBr/KSCN. A practical application of this is given in Section 19.9. 

One test for the presence of iron(III) ions in solution is to add a solution of potassium thiocyanate, KSCN, and obtain the blood-red color of a compound of iron and the thiocyanate ion. Write three Lewis structures with different atomic arrangements for the... 

M iron(lll) chloride (FeCI3) 0AM potassium thiocyanate (KSCN)... 

Condensations of amine hydrohalides with potassium thiocyanate (KSCN) provide both the primary thioureas and symmetrical 7V,7V -disubstituted thioureas. Selectivity in the product was achieved by changing the concentration of KSCN as shown in the diagram (Scheme 50).131... 

Weanling males fed diets containing 1500 mg KCN/kg, or 2240 potassium thiocyanate (KSCN) for 50 weeks No deaths or clinical signs of toxicity. Both groups had decreased thyroid gland activity. Cyanide, but not thiocyanate, caused reduction in growth rate 38... 

Potassium thiocyanate (KSCN) is considered to be the choicest internal standard. In usual practice, it must be preground, dried and subsequently reground, and used at a concentration of 0.2% (w/w) along with the dried spectroscopic grade KBr. The mixture of KBr-KSCN is stored over P205. 

NH4SCN is weakly acidic reacts with caustic soda or caustic potash to form sodium thiocyanate (NaSCN) or potassium thiocyanate (KSCN). It reacts with ferric salts to form a deep-red ferric thiocyanate complex ... 

Chloride is analyzed by some form of reaction with silver to form insoluble silver chloride. Direct titration of milk with silver nitrate yields erroneously high and variable results, and pre-ashing cannot be used because chloride is lost by volatilization. Satisfactory procedures involve adding an excess of standardized AgN03 directly to milk and back titrating with potassium thiocyanate (KSCN), using a soluble ferric salt as the indicator (Sanders 1939). 

Often, greater accuracy may be obtained, as in Volhard type titration, by performing a back titration of the excess silver ions. In such a case, a measured amount of standard silver nitrate solution is added in excess to a measured amount of sample. The excess Ag+ that remains after it reacts with the analyte is then measured by back titration with standard potassium thiocyanate (KSCN). If the silver salt of the analyte ion is more soluble than silver thiocyanate (AgSCN), the former should be filtered off from the solution. Otherwise, a low value error can occur due to overconsumption of thiocyanate ion. Thus, for the determination of ions (such as cyanide, carbonate, chromate, chloride, oxalate, phosphate, and sulfide, the silver salts of which are all more soluble than AgSCN), remove the silver salts before the back titration of excess Ag.+ On the other hand, such removal of silver salt is not necesary in the Volhard titration for ions such as bromide, iodide, cyanate, thiocyanate, and arsenate, because the silver salts of these ions are less soluble than AgSCN, and will not cause ary error. In the determination of chloride by Volhard titration, the solution should be made strongly acidic to prevent interference from carbonate, oxalate, and arsenate, while for bromide and iodide analysis titration is carried out in neutral media. 

Thiocyanate standard solns. 1.673 g potassium thiocyanate, KSCN in distilled water, diluted to 1 L. This stock soln. = 1000 mg SCN7L or 1 mL = 1 mg SCN". Prepare a secondary standard from the stock solution by diluting 1 mL stock solution to 100 mL with distilled water. Secondary std = 10 mg SCN-/L or 1 mL = 0.01 mg SCN". Prepare a series of calibration standards by diluting the secondary standard with distilled water as follows ... 

To study these reactions use a 0- 1m solution of potassium thiocyanate KSCN. 

Iron(III) thiocyanate (0-05m). Dissolve 1-35 g iron(III) chloride hexahydrate, FeCl3.6H20, and 2 g potassium thiocyanate, KSCN, in water and dilute the solution to 100 ml. 

Carbon dioxide (CO2) 11.2 Nitrogen (N2) 4.2 Carbon monoxide (CO) 1.1 Water vapor (HjO) 1.1 Hydrogen sulfide (H2S) 0.1 Methane (CH4 0.1 Hydrogen (Hj) 34.1 Potassium carbonate (KjCOj) 8.4 Potassium suifate (K2SO4) 8.1 Potassium suifide (KjS) 4.9 Suifur(S) 0.2 Potassium nitrate (KNOj) 0.1 Potassium thiocyanate (KSCN) 0.1 Ammonium carbonate ((NH4)2CO ) 0.1 Carbon (C)... 

Figure 4 Absorption (transmission) spectrum for a serum film dried onto a barium fluoride window. The specimen was first diluted twofold in aqueous 4gL potassium thiocyanate (KSCN) solution. The absorption of SON" at 2060 cm" was used for subsequent normalization of the spectra as part of the development of quantitation models (see Shaw et al. )-...

Standard Ag" was prepared by mixing 25.00 mL of 0.102 6 M AgN03, 5 mL of 6 M HNO3, and 1 mL of Fe indicator solution (40 wt% aqueous (NH4)Fe(S04)2 with a few drops of 6 M HNO3). To standardize a solution of potassium thiocyanate, KSCN is delivered to the standard Ag solution from a buret. The initial precipitate is white and later it is reddish brown. The color disappears on shaking. At the end point, one drop of KSCN solution produces a faint brown color that does not disappear on shaking. A volume of 24.22 mL was required to reach the end point and the blank correction was 0.02 mL. 

The (SCN)2 ions produced in the pulse irradiation of potassium thiocyanate (KSCN) aqueous solution show transient optical absorption with a maximum at 475 nm. 

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