Equations Potassium chromate

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. 

Self-Test I.2A Write the net ionic equation for the reaction in Fig. 1.1, in which aqueous solutions of colorless silver nitrate and yellow potassium chromate react to give a precipitate of red silver chromate. 

Preparation of Potassium Chromate. (Perform one experiment on each table.) Melt a mixture of 1 g of potassium carbonate, 1 gof potassium hydroxide, and 2 g of potassium nitrate in an iron crucible by heating with the flame of a burner. While stirring the melt with an iron wire, introduce 1 g of finely comminuted chromite or -0.8 g of chromium oxide into the crucible. Roast the mixture for 5-10 minutes on a blowpipe. Treat the cooled melt with water. Filter the solution and evaporate it until a crystalline film appears. What is the composition of the formed crystals Why was potassium carbonate introduced into the reaction Write the equation of the reaction. 

Properties of Chromic Acid Salts. 1. Dissolve a small amount -of the prepared potassium chromate in water and add dilute sulphuric acid. What is the change in the solution s colour due to How does the composition of chromic acid salts change depending on the reaction of the medium Write the equations of the reactions,... 

Pour an ammonium sulphide solution into a potassium chromate or dichromate solution and heat the mixture. How does the solution s colour change What is the composition of the precipitate Write the equation of the reaction. What properties does chromium (VI) exhibit in this reaction How does an acidified potassium chromate or dichromate solution react with hydrogen sulphide, sulphur dioxide, and an iron(II) salt Write the equations of the reactions. 

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. 

Write a balanced net ionic equation for the production of the yellow precipitate when potassium chromate is added to the paint chip and yellow lead chromate precipitate is formed. 

Dissolve a small amount of your preparation in 10 cc. of water. Divide this solution into three portions. To one add a drop of sulphuric acid to the second add a drop of potassium chromate to the third add a drop of silver nitrate. Record your observations and write ionic equations for each reaction. 

This expression shows that under equilibrium conditions the concentration of chromate ions in the solution is always much greater than that of the chloride ions. If therefore to a mixture of chloride and chromate ions, silver ions are added, these will combine with chloride ions, forming silver chloride precipitate until the concentration of chloride ions in the solution decreases to such an extent, that the ratio expressed in equation (iii) is achieved. From then onwards the two precipitates will be formed simultaneously. If a 01m solution of sodium chloride is titrated with silver nitrate in the presence of 0 002m potassium chromate, the concentration of chloride ions at which silver chromate starts to precipitate can be expressed from equation (iii) ... 

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 ... 

Although this equation shows the reactants and products of the reaction, it does not give a very clear picture of what actually occurs in solution. As we have seen, aqueous solutions of potassium chromate, barium nitrate, and potassium nitrate contain the individual ions, not molecules, as is implied by the molecular equation. Thus the complete ionic equation... 

Potassium chromate and lead(II) acetate are both dissolved in a beaker of water, where they react to form solid lead(II) chromate. What is the balanced net ionic equation describing this reaction ... 

Potassium chromate is used as an indicator in titrations for the determination of chloride ion. At the end point of a titration of an aqueous solution of a metal chloride salt (e.g. NaCl) against silver nitrate solution in the presence of potassium chromate, red Ag2Cr04 precipitates. Give equations for the pertinent reactions occurring during the titration, and, using relevant data from Table 6.4, explain how the indicator works. 

If solutions of potassium chromate and barium chloride are mixed, a bright yellow solid (barium chromate) forms and settles out of the mixture, leaving potassium chloride in solution. Write a balanced chemical equation for this process. 

Potassium chromate in HMPT reacts with a variety of substrates in a crown catalyzed nucleophilic displacement. Both dicyclohexyl- and dibenzo-18-crown-6 catalyze the formation of chromate esters which decompose according to equation 11.5 to yield oxidized product [11]. 

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