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It must be that lead dichromate is the bright yellow precipitate. If you have some experience with salt peter (potassium nitrate), you know that it is soluble. The other pairing (lead dichromate and potassium nitrate) must lead to the precipitate. We have tried one of those pairings (lead nitrate and potassium dichromate) and know that the result is soluble salts. Only two of the six pairings make sense, as we need to combine a positively charged cation (lead or potassium) with a negatively charged anion (dichromate or nitrate).

There are six unique pairings of the four ions. What is the precipitate?Ĭonsider the four ions initially in solution: nitrate, potassium, dichromate, and lead. Mixing the two solutions leads to the dramatic formation of a bright yellow precipitate. The soluble salts form colorless (lead nitrate) or lightly tinted (potassium dichromate) solutions.

Add a few drops of potassium dichromate solution and observe the reaction. Transfer a quantity of lead nitrate solution into an Erlenmeyer flask or test tube.ģ. Prepare separate solutions of soluble potassium dichromate and lead nitrate salts.Ģ. Ingredients: lead nitrate, potassium dichromateġ. Cations and anions combine to form a bright yellow precipitate. Solutions of soluble salts are prepared and mixed. This reaction provides an excellent means of analyzing a sample for the presence of ferric ion, through the addition of a small quantity of soluble thiocyanate salt. The balanced equation for the reaction isĦ KSCN(aq) + Fe 2(SO 4) 3(aq) → 6 K +(aq) + 3 SO 4 2-(aq) + 2 Fe(SCN) 3(s) So we identify ferric thiocyanate as the precipitate. From our experience with sodium salts (like table salt, sodium chloride) we expect that sodium sulfate is soluble. The other pairing (ferric thiocyanate and potassium sulfate) must lead to the precipitate. We have tried one of those pairings (ferric sulfate and potassium thiocyanate) and know that the result is soluble salts. Only two of the six pairings make sense, as we need to combine a positively charged cation (ferric or potassium) with a negatively charged anion (sulfate or thiocyanate). Think of the four ions initially in solution: sulfate, potassium, thiocyanate, and ferric. Mixing the two solutions leads to the dramatic formation of a deeply colored "blood red" precipitate. The soluble salts form lightly tinted (ferric sulfate) or colorless (potassium thiocyanate) solutions. Add a few drops of potassium thiocyanate solution and observe the reaction.

Transfer a quantity of ferric sulfate solution into an Erlenmeyer flask or test tube.ģ. Prepare separate solutions of soluble potassium thiocyanate and ferric sulfate salts.Ģ. Ingredients: ferric sulfate, potassium thiocyanateġ. Mixing the solutions leads to the startling formation of a "blood red" precipitate.