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SNC1D/1P Name: ____________________________ CHEMICAL IDENTIFICATION TESTS FOR GASES Learning Goal: At the end of this experiment, I will be able to use standard tests to identify 3 common unknown gases. Purpose: To identify the gas produced during three chemical reactions Materials: ● ● ● ● ● ● ● ● ● safety goggles piece of zinc magnesium ribbon 1.0 mol/L hydrochloric acid sodium bicarbonate vinegar scoopula limewater 3% hydrogen peroxide yeast ● ● ● ● ● ● ● ● ● 10 mL graduated cylinder Forceps (tweezers) distilled water 4 clean test tubes rubber stopper test tube rack wooden splints Bunsen burner matches/flint sparker Safety Precautions: ● Put on splash-proof goggles and lab apron before beginning the lab. ● Hydrochloric acid and hydrogen peroxide are corrosive. ● Wash hands after completing the lab. Procedures: (5 marks for safety, procedure and clean-up) Part 1: Reaction of Hydrogen Peroxide and Yeast 1. Measure 10 mL of 3% hydrogen peroxide in the 10 mL graduated cylinder. Slowly pour the hydrogen peroxide into the test tube. Record a description of the hydrogen peroxide in your observation table. 2. Cover the tip of a scoopula with a pencil eraser sized amount of yeast. Record a description of the yeast in your observation table. Add the yeast into the test tube containing the hydrogen peroxide. Plug the test tube with a rubber stopper. Record your observations of the chemical reaction in your data table. 3. Light a wooden splint with the Bunsen burner, then blow out its flame. Insert the glowing splint (fig. 1) halfway into test tube. Record your observations in your observation table. 4. Dispose of the contents into the waste container. 1 SNC1D/1P Name: ____________________________ Part 2: Reaction of Zinc and Hydrochloric Acid 1. Measure 5.0 mL of 1.0 mol/L hydrochloric acid in a 10 mL graduated cylinder. Slowly pour the hydrochloric acid into the test tube. Record a description of the hydrochloric acid in your observation table. 2. Using forceps place a piece of zinc on a dry watch glass. Record a description of the zinc in your observation table. 3. Using forceps, carefully add the zinc into the test tube containing the hydrochloric acid. Plug the test tube using the rubber stopper. Record your observations in your observation table. 4. Light a wooden splint with the Bunsen burner and bring the still burning splint (fig. 2) to the mouth of the test tube. Record your observations in your data table. 5. Dispose of the contents of your test tube into the waste container. Part 2: Reaction of Sodium Bicarbonate and Vinegar 1. Set up two test tubes in the test tube rack. Measure 5.0 mL of vinegar in a 10 mL graduated cylinder. Slowly pour the vinegar into one of the test tubes. Record a description of the vinegar in your observation table. 2. Measure 5.0 mL of limewater in a 10 mL graduated cylinder. Record a description of the limewater in your observation table. 3. Cover the tip of a scoopula with about a pencil eraser amount of sodium hydrogen carbonate. Record a description of the solid in your observation table. 4. Add the sodium hydrogen carbonate into the test tube containing the vinegar. Record your observations. 5. When the bubbling stops slowly pour the gas produced into the test tube containing the limewater. Stopper the test tube containing the limewater and shake the contents gently. Record your observations in your observation table. 6. Dispose of the contents of the test tube into the waste container. Analysis & Extension: 1. Using your table of observations, identify each gas produced in the reactions. Explain your reasoning for choosing each gas. Hint: characteristic properties! (3) 2. In each part of the activity, were the changes physical changes or chemical changes? Provide reasons for your answers. (2) 3. From your observations in this activity, suggest reasons why a) Birthday balloons are filled with helium, not hydrogen. (1) b) During surgery using oxygen cylinders, medical staff wear coverings over their shoes to eliminate sparks produced by static electricity. (1) 2 SNC1D/1P Name: ____________________________ COMPLETE AND SUBMIT ONLY THIS PORTION OF THE LAB FOR MARKS. Observations: (3) Reactants Description of reactants Description of product Burning splint test Glowing splint test Limewater test Zinc and Hydrochloric Acid Sodium Hydrogen Carbonate and Vinegar Hydrogen peroxide and yeast Properties of some common lab gases at room temperature: Oxygen: Hydrogen: Carbon Dioxide: Water Vapour: Methane: colourless, odourless, tasteless gas, it is highly reactive and a strong oxidizer. colourless, odourless, tasteless gas, it is highly flammable and explosive. colourless, odourless, tasteless gas, it is not very reactive and extinguishes flames. colourless, odourless, tasteless gas, mildly reactive, condenses easily on cool objects. colourless, odourless (naturally), tasteless gas, highly flammable – an odourant is added when used in homes and industry for safety. Analysis & Extension: Answer the analysis and extension questions on the back. Title & number your responses. 3