Lecture
Pour 4–5 cm3 of starch paste diluted with water into a test tube, then add approximately the same volume of 10% sulfuric acid. To ensure even boiling, add a little dry sand or pieces of porcelain. Carefully heat the mixture to boiling and boil for a few minutes. After boiling, cool the mixture and neutralize it with sodium hydroxide solution. Monitor the reaction of the medium using strips of indicator paper.
Prepare a precipitate of copper(II) hydroxide and divide it into two portions. To the first, add the original starch paste; to the second — the product of its hydrolysis. Heat the mixture in both test tubes. Explain the change in color of the contents of each test tube.
Comments