Chromate . potassium

HUMAN CARCINOGEN AS DUST, CONTACT WITH COMBUSTIBLE MATERIAL MAY CAUSE FIRE 

Dust irritates the respiratory tract and eyes. Swallowing causes irritation and internal damage. Prolonged exposure causes ulceration, damage to liver and kidneys, and even cancer. Carcinogen as dust. Avoid inhaling dust. Avoid contact with eyes and skin.2 TLV-TWA 0.05 mg/m3.3 

Small Quantities. Wear eye protection, laboratory coat, and nitrile rubber gloves. For each 2 g quantity of potassium chromate, add at least 100 mL of H20. Acidify with 

Reactions for Spillage and Waste Disposal IKiCrO, + 3N gS3Os + 5H20 - 2Cr(OH)3 + 3Na2SO+ + 3S + 4KOH 

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Addition of silver nitrate to a solution of a chloride in dilute nitric acid gives a white precipitate of silver chloride, AgCl, soluble in ammonia solution. This test may be used for gravimetric or volumetric estimation of chloride the silver chloride can be filtered off, dried and weighed, or the chloride titrated with standard silver nitrate using potassium chromate(VI) or fluorescein as indicator. 

Silver nitrate is used volumetrically to estimate chloride, bromide, cyanide and thiocyanate ions. Potassium chromate or fluorescein is used as an indicator. 

In neutral solution, the indicator is potassium chromate(VI). In acid solution the CrOj" ion changes to CrjO (p. 378). and since silver dichromatefVI) is soluble, chromate(VI) is not a suitable indicator other methods can be used under these conditions. (In alkaline solution, silverfl) oxide precipitates, so silver(I) nitrate cannot be used under these conditions.)... 

Potassium chromate(VI) gives a brick-red precipitate of silver chromate(VI) in neutral solution. 

Sihcon carbide is comparatively stable. The only violent reaction occurs when SiC is heated with a mixture of potassium dichromate and lead chromate. Chemical reactions do, however, take place between sihcon carbide and a variety of compounds at relatively high temperatures. Sodium sihcate attacks SiC above 1300°C, and SiC reacts with calcium and magnesium oxides above 1000°C and with copper oxide at 800°C to form the metal sihcide. Sihcon carbide decomposes in fused alkahes such as potassium chromate or sodium chromate and in fused borax or cryohte, and reacts with carbon dioxide, hydrogen, ak, and steam. Sihcon carbide, resistant to chlorine below 700°C, reacts to form carbon and sihcon tetrachloride at high temperature. SiC dissociates in molten kon and the sihcon reacts with oxides present in the melt, a reaction of use in the metallurgy of kon and steel (qv). The dense, self-bonded type of SiC has good resistance to aluminum up to about 800°C, to bismuth and zinc at 600°C, and to tin up to 400°C a new sihcon nitride-bonded type exhibits improved resistance to cryohte. 

Manufacture The primary iadustrial compounds of chromium made directly from chromite ore are sodium chromate, sodium dichromate, and chromic acid. Secondary chromium compounds produced ia quantity include potassium dichromate, potassium chromate, and ammonium dichromate. 

Potassium chromate is prepared by the reaction of potassium dichromate and potassium hydroxide. Sulfates are the most difficult impurity to remove, because potassium sulfate and potassium chromate are isomorphic. 

Zinc chromates (including zinc potassium chromate)... 

Dinickel trioxide Nickel dioxide Nickel monoxide Nickel subsulphide Nickel sulphide Potassium chromate Potassium dichromate... 

Methyl 3-Carbethoxyoxy-7-keto-12a-hydroxycholanate. A solution of 4 g (8.6 mmoles) of crude methyl 3-carbethoxyoxycholate in 50 ml of acetic acid containing 10 g of sodium acetate trihydrate is treated gradually with a solution of 3 g (0.015 mole) of potassium chromate in 8 ml of water with shaking. After 10 hr at 25° the solution is diluted with water and the product collected by filtration to afford 3.9 g (97%) of methyl 3-carbethoxyoxy-7-keto-12a-hy-droxycholanate, mp 150-158°. Crystallization from methanol gives hard, compact needles or rods mp 157-158° 41°. The same substance is... 

Cathylates are stable to oxidation with potassium chromate in acetic acid and with A-bromoacetamide, acetylation and formylation with 85 % formic acid at room temperature. They are cleaved by bases to give the parent alcohol, carbon dioxide and ethanol. 

N. Curtis, D. G. Leaist. Interdiffusion of aqueous silver nitrate and potassium chromate and the periodic precipitation of silver chromate Liesegang bands. Ber Bunsen-Ges—Phys Chem, Chem Phys 702 164, 1998. 

Chrom-kali, n. (rotes) potassium dichromate (gelbes) potassium chromate, -karbid, n. chromium carbide, -lack, m. chrome lake, -leder, n. chrome leather, -leim, m. chrome gelatin chrome glue, -metall, n. chromium metal, -natron, n. (rotss) sodium dichromate (gelbes) sodium chromate, -nickel-stahl, m. chrome-nickel steel. 

Chloride. The chloride concentration is determined by titration with silver nitrate solution. This causes the chloride to be removed from the solution as AgCl, a white precipitate. The endpoint of the titration is detected using a potassium chromate indicator. The excess Ag present after all Cl" has been removed from solution reacts with the chromate to form Ag CrO, an orange-red precipitate. 

Sodium Chloride [25]. Sodium chloride estimation is based on sodium titration. To 20 ml of a 1 1 mixture of toluene (xylene) isopropyl alcohol, add a 1-ml sample of oil-base mud, stirring constantly and 75 to 100 ml of distilled water. Add 8-10 drops of phenolphthalein indicator solution and titrate the mixture with H SO (N/10) until the red (pink) color, if any, disappears. Add 1 ml of potassium chromate to the mixture and titrate with 0.282N AgNO (silver nitrate, 1 ml = 0.001 g chloride ions) until the water portion color changes from yellow to orange. Then... 

Preparing one liter of 0.100 Of potassium chromate. A 0.100 M potassium chromate solution is made by adding enough water to 19.4 g of K2C1O4 to make one liter of solution. 

Before lead in paint was discontinued, lead chromate was a common pigment in yellow paint. A 1.0-L solution is prepared by mixing 0.50 mg of lead nitrate with 0.020 mg of potassium chromate. Will a precipitate form What should [Pb2+] be to just start precipitation ... 

Molarity (M) A concentration unit defined to be the number of moles of solute per liter of solution, 95q, 259 concentration unit conversion, 261-262 potassium chromate, 263 Mole A collection of6.0122 X 1023 items. The mass in grams of one mole of a substance is numerically equal to its formula mass, 55. See also Amount Mole fraction (X) A concentration unit defined as the number of moles of a component divided by the total number of moles, 116-117,261 Mole-gram conversions, 55-56,68-68q... 

Potassium chromate, 76,263 Potassium dichromate, 77-78 Potassium iodide, 499 Potassium permanganate, 17,288,549 Potassium superoxide, 543-544 Powell, H. M 175... 

When solutions of barium chloride, BaCl2, and potassium chromate, K-2Cr04, are mixed, the following reaction occurs ... 

The color of a solution of potassium chromate, K2Cr04, changes to the color of a solution of potassium dichromate, K2Gr2C>7, when a few drops of HQ solution are added. Write the balanced equation for the reaction between CrO t2(aq) and H+(aq) to produce Cr207-2 and explain the color change on the basis of Le Qiatelier s Principle. 

Anion exchange resin. Proceed as in the previous experiment using 1.0 g, accurately weighed, of the air-dried strongly basic anion exchanger (e.g. Duolite A113, chloride form). Fill the 250 mL separatory funnel with ca 0.25M sodium nitrate solution, and allow this solution to drop into the column at the rate of about 2 mL per minute. Collect the effluent in a 500 mL conical flask, and titrate with standard 0.1M silver nitrate using potassium chromate as indicator. 

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