Potassium chromate, reaction with barium

Pour potassium chromate and dichromate solutions into separate test tubes and add a solution of a barium salt to each of them. What is the composition of the precipitates See how the obtained salts react with dilute acids. Perform similar experiments with a lead salt. Write the equations of the reactions. 

If barium is present, proceed as follows. Impregnate some quantitative filter paper or drop-reaction paper with a saturated solution of potassium chromate, and dry it. Place a drop of the test solution on this paper and, after a minute, place 1 drop of the reagent on the moistened spot. A brownish-red spot or ring is formed. 

When two solutions are mixed, an insoluble substance sometimes forms that is, a solid forms and separates from the solution. Such a reaction is called a precipitation reaction and the solid that forms is called a precipitate. For example, a precipitation reaction occurs when an aqueous solution of potassium chromate, K2Cr04(aq), which is yellow, is mixed with a colorless aqueous solution containing barium nitrate, Ba(N03)2(aq). As shown in Fig. 4.12, when these solutions are mixed, a yellow solid forms. What is the equation that describes this chemical change To write the equation we must know the identities of the reactants and products. The reactants have already been described K2Cr04(aq) and Ba(N03)2(tf<7). Is there some way we can predict the identities of the products In particular, what is the yellow solid ... 

In this section we will consider the types of equations used to represent reactions in solution. For example, when we mix aqueous potassium chromate with aqueous barium nitrate, a reaction occurs to form a precipitate (BaCr04) and dissolved potassium nitrate. So far we have written the molecular equation for this reaction ... 

It has been involved in many industrial explosions. Explodes on contact with aluminum + barium nitrate + potassium nitrate + water. Forms explosive mixtures with aluminum powder + titanium dioxide, ethylene glycol (240°C), cotton lint (245°C), furfural (270°C), lactose, metal powders (e.g., aluminum, iron, magnesium, molybdenum, nickel, tantalum, titanium), sulfur, titanium hydride. Reaction with ethanol + heat forms the explosive ethyl perchlorate. Violent reaction or ignition under the proper conditions with aluminum + aluminum fluoride, barium chromate + mngsten or titanium, boron + magnesium + silicone rubber, ferrocenium diammine-tetrakis(thiocyanato-N) chromate(l —), potassium hexacyanocobaltate(3—), A1 +... 

AMMONIUM NITRATE (6484-52-2) A strong oxidizer. An ingredient in dynamite. Violent reaction and/or the formation of explosive mixtures with hot water, reducing agents, combustible materials, organic materials, ammonium dichromate, barium chloride, barium nitrate, charcoal, cyanoguanidine, phosphorus, potassium chromate, potassium dichromate, potassium nitrate, potassium permanganate, sodium chloride, finely divided metals. Forms explosive or heat- and shock-sensitive compounds with acetic acid, alkali metals (potassium, sodium, etc.), ammonia, nitric acid, sodium hypochlorite, sulfur, urea. At elevated temperatures, contained or confined material may explode violently. 

The precipitation reaction that occurs when yellow potassium chromate, K2CrO aq), is mixed with a colorless barium nitrate solution, Ba(N03)2(aq)... 

P. D. Chrustschufi and A. Martinofi observed that 12 per cent, of barium sulphate. is converted into barium chromate by contact for 47 min. with a soln. containing potassium sulphate and potassium chromate in eq. proportions, whilst 1-5 per cent, of barium chromate is converted into barium sulphate in the same time in contact with a similar soln. The limits of the reaction do not attain more than 22 per cent, and 17 per cent, respectively, even after 40 to 45 hrs. M. Scholtz and R. Abegg found that at 100°, equilibrium between barium sulphate and potassium chromate. in aq. soln. is established very slowly it is reached more rapidly when a soln. of potassium sulphate acts on barium chromate. The ratio between the quantities... 

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