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23 Experiment 5. Oxidizing properties of manganese compounds (VII). In three tubes, add a solution of potassium permanganate KMnO 4. In the first tube add dilute sulfuric acid, in the second – аwater, in the third – a concentrated solution of alkali. Add sodium sulfite solution Na 2 SO 3  to each of the tubes. Explain what is happening. Write the reaction equations, arrange the coefficients by the electronic balance method. Experiment 6. Oxidizing properties of iron (III) compounds. To a solution of iron (III) salt acidified with hydrochloric acid, add a solution of potassium io- dide KI. What are you watching? Write the reaction equations, arrange the coef- ficients by the electronic balance method. Experiment 7. Qualitative reactions to iron (II) and iron (III) ions. 1) Add a solution of iron (II) salt to two test tubes. In the first tube, add the yellow blood salt K 4 [Fe (CN) 6 ], and in the second test tube the red blood salt K 3 [Fe (CN) 6 ]. What are you watching? Write the reaction equations. 2) Add the ferric (III) salt solution into two test tubes. In the first tube, add the yellow blood salt K 4 [Fe (CN) 6 ], and in the second test tube the red blood salt K 3 [Fe (CN) 6 ]. What are you watching? Write the reaction equations. Experiment 8. Preparation of copper and zinc hydroxides and investigation of their properties. In separate test tubes, add solutions of copper and zinc salts. In each tube add a solution of sodium hydroxide NaOH to precipitate. The precipitate in each test tube is divided into parts. Add an excess of alkaliin one of these tubes. What are you watching? Add an excess of ammonia to the other tube. What are you watching? Explain the observed phenomena and write the reaction equations in ionic and molecular form. Experiment 9. Boron acid detection reaction (performed in a fume hood!). Place in the porcelain cup several crystals of boric acid H 3 BO 3. Add 3–4 drops of concentrated sulfuric acid and mix thoroughly, then add 2–3 ml of ethanol and also mix the mixture. Burn the alcohol solution, observe the coloration of the flame. Write the equation for the reaction of formation of boron-ethyl ether. Experiment 10. Complex compounds of lead. Add 2–3 drops of lead (II) nitrate solution to the tube, then add a few drops of potassium iodide solution until a yellow precipitate is deposited. Add excess solution of potassium iodide. Does the excess of KI influence the solubility of the precipitate? Heat the test tube with the solution on the spirit lamp. Observe the solubility of the precipitate. Write the reaction equations.