Changes In Matter

Ralph Loris Lagas 3-A

“CHANGES IN MATTER” Introduction: There are enumerable changes taking place in the things around us. Rocks weather and form soil; milk curdles with vinegar; water decomposes into hydrogen and oxygen gases with the action of electricity; iron rust; and many more changes that do not alter the chemical composition of the original substances are referred to as physical changes. When pure substances are transformed into one or more other pure substances, a chemical change has taken place. The formation of new pure substances happens only other suitable conditions. Objectives: After completing the activity, you should be able to identify the difference between physical and chemical changes in matter. Materials: 250 ml beaker, 10ml graduated cylinder, 5 test tubes, 3 evaporating dishes, iron ring with iron stand, burner, funnel, tongs, spatula, wire gauze, thermometer, crushed ice, magnesium ribbon, sodium chloride, solid ammonium chloride, hydrochloric acid and concentrated sulfuric acid. Procedure: A.1) in the test tube filled halfway with, add about level spatula of sodium chloride. Shake until all the salt is dissolved. Transfer the solution into an evaporating dish and heat dryness. 2) In another test tube filled with 5ml of hydrochloric acid, place a piece of magnesium ribbon. When the metal has dissolved completely, transfer the liquid into an evaporating dish and heat to near dryness. NOTE: While waiting for the result of A. proceed with other parts of the experiment.

B.1) Fill 3 test tubes halfway with water. 2) Into the first, add 3ml of concentrated sulfuric acid. CAUTION: Add the acid slowly, folding the test tube in an inclined position. Into the second, add a spatula of sodium chloride, and into third spatula of ammonium chloride. 3) Fill each test tube with your palm. Note any thermal change. C.1) Fill about ¾ of the beaker with crushed tie. 2) Insert a thermometer and note the lowest temperature registered. 3) Observed whether the temperature remains constant. Continue observing change, if any, until 2 or 3 minutes after the last ice crystals has disappeared. D.1) Boil half a breaker of water. Record the temperature at which the steam escapes vigorously, and note whether the temperature remains constant. 2) Hold a dry evaporating dish 2 or 3cm above the beaker. Record your observation.