Physical and Chemical Properties and Changes. Part I: Physical and Chemical Properties

Transcription

1 Physical and Chemical Properties and Changes The following lab will be completed over the course of two days and then handed in for evaluation. You will be working in small groups; the members of your group are expected to stay the same for the entire duration of the lab (both days). Objectives To become familiar with the characteristics of matter, which include both physical and chemical properties. To understand, and distinguish between, a physical and chemical change. Part I: Physical and Chemical Properties Materials - 6 small pieces of paper - Iodine solution - Iron fillings - Spot plate - Distilled water - bicarbonate - Test tube rack - Sulfur - chloride - Magnet - Magnesium ribbon - Unknown solid - Scoopula - Cornstarch - Vinegar ***YOU MUST WEAR SAFETY GOGGLES AT ALL TIMES*** Procedure 1. On the small sheets of paper provided, label each with the name of one of the following: sulfur, magnesium, iron, sodium bicarbonate, sodium chloride, cornstarch, and unknown. 2. Obtain two small pieces of magnesium ribbon and place them on the appropriately labeled paper. For the other substances, use a clean scoopula to transfer a pea-sized sample to the other appropriately labeled papers. 3. Carefully examine each sample, but do not taste or touch any of the substances. Record your findings for State, Colour, Odor, and Magnetism in the Observation Table. Note: To test for magnetism, run the magnet under the piece of paper so that the magnet does not come into direct contact with the substances. 4. Carefully transfer your samples into a spot plate. Each substance must be divided into three separate wells. 5. Carefully fill one well of each substance with distilled water. Record your findings for Solubility. 6. Add 3-5 drops of vinegar to one well of each substance. Record your findings for Reacts with Vinegar. 7. Add 3-5 drops of Iodine Solution to one well of each substance. Record your findings for Iodine Solution. 8. Dispose of the liquid contents of the spot plate into the sink; solids must go in the waste. Wash and dry the materials. Clean up your station and leave it in the same condition that it was in when you arrived.

2 Physical and Chemical Properties: Observations Table Substance Physical State (solid, liquid, gas) Colour Odor Magnetic Solubility Reacts with Vinegar Iodine Solution* Sulfur (S) Magnesium (Mg) Iron (Fe) Bicarbonate (NaHCO 3 ) Chloride (NaCl) Cornstarch Unknown *Iodine tests for the presence of starch in a substance

3 Discussion and Analysis This section is to be completed individually. 1. Distinguish the tests used today as either Physical Properties or Chemical Properties. [7 marks] Physical Properties Chemical Properties 2. Identify the Unknown Substance. State which test was most beneficial in determining it s identity and explain why. [3 marks] 3. Read the following description for the element sulfur and identify all of the given physical (qualitative and quantitative) and chemical properties. List them in the chart below. [12 marks] Sulfur is an element that is known for its bright yellow colour. It is a solid non-metal with a melting point of C and a boiling point of C. If visible, the crystals have a cubic form with a density of 2.07 g/cm 3. Sulfur combines with many other elements to form compounds. For example, sulfur will react with magnesium (Mg) to form magnesium sulfide (MgS). Sulfur is not soluble in water, but is soluble in other liquids, such as benzene, carbon tetrachloride, and carbon disulfide. Sulfur will react with oxygen to form sulfur dioxide (SO 2 ). However, you are probably more familiar with hydrogen sulfide (H 2 S) it smells like rotten eggs! This is the compound formed when sulfur reacts with hydrogen gas. Chemical Properties Qualitative Physical Properties Quantitative Physical Properties

4 Part II: Physical and Chemical Changes This part of the lab will require you to work with the substances that you became familiar with in Part I, as well as silver nitrate (AgNO 3 ) and hydrochloric acid (HCl). Both of these substances are corrosive, so please exercise caution during this lab and wear safety goggles at all times. Even the slightest contact with silver nitrate can stain your skin. Materials - 2 small pieces of paper - Distilled water - Silver nitrate - 3 test tubes - Iron fillings - bicarbonate - Test tube rack - Sulfur - Magnesium ribbon - Magnet - Iron sulfide - Hydrochloric acid - Scoopula - chloride ***YOU MUST WEAR SAFETY GOGGLES AT ALL TIMES*** Procedure 1. Label a piece of paper with Iron + Sulfur. Combine a pea-sized sample of iron with a pea-sized sample of sulfur onto it. Using a scoopula, make sure that the two substances are evenly mixed together. As you did in Part I, run the magnet underneath the sheet of paper. Record your results. 2. Label a piece of paper with Iron Sulfide. Obtain a pea-sized sample of iron sulfide (FeS), which is iron and sulfide bonded together, and therefore different from the substances in Step 1. Repeat the magnetic test and record your observations. 3. Add a small amount of sodium chloride (NaCl) into a test tube containing 3 cm of distilling water. Mix the contents by flicking the base of the test tube with your finger. Record your observations. 4. Cautiously add 5-10 drops of silver nitrate (AgNO 3 ) to the test tube that contains your sodium chloride and water solution. Record your results. 5. Place a small strip of magnesium ribbon into a clean, dry test tube. The test tube should be held in a test tube rack. Add 5-10 drops of hydrochloric acid to the test tube. Remember that hydrochloric acid is corrosive, so exercise caution! Fell the bottom of the test tube. Record your observations. 6. Transfer a pea-sized amount of sodium bicarbonate to a clean, dry test tube. Again, the test tube should be held in a test tube rack. Carefully add 5-10 drops of hydrochloric acid to the test tube. Feel the bottom of the test tube. Record your observations. 7. Dispose of the contents of the test tubes into the waste beaker. Solids can be disposed of in the garbage can. Clean up all of your equipment and leave your lab station in the same condition that it was in when you arrived.

5 Physical and Chemical Changes: Observation Table Task Substance Observations Performed Physical or Chemical Change? Sulfur (S) + Iron (Fe) Iron Sulfide (FeS) Chloride (NaCl) Chloride (NaCl) Magnesium (Mg) Bicarbonate (NaHCO 3 ) Magnet test Magnet test Mixed with water Reaction with Silver Nitrate (AgNO 3 ) Reaction with acid Reaction with acid Discussion and Analysis This section is to be completed individually. 1. List four observations that indicate when a chemical change has probably occurred. 2. The following is a list of reactions. Classify each as either a physical (P) or chemical change (C). Use the back of this page or a piece of lined paper to justify your answers. a) Mixing a bowl of cereal and milk. b) Mixing baking soda and vinegar. c) Mixing equal portions of red and blue paint. d) Lighting a match. e) Roasting a marshmallow. f) Crushing an empty pop can. g) Lighting a firework. h) Tearing up a test with a poor mark.

6 Physical and Chemical Properties and Changes Name: Evaluation of Marks 26 Marks - Observations 34 Marks Discussion and Analysis Questions (mark distribution as shown throughout the lab) 5 Marks Laboratory Techniques and Safety CRITERIA EXCELLENT GOOD SATISFACTORY NEEDS IMPROVEMENT observation tables are complete observation tables are complete observation tables are complete observation tables are OBSERVATIONS and void of mistakes and void of mistakes observations lack detail incomplete Part 1 observations show great detail observations could include more several mistakes present observations are missing 14 marks detail multiple mistakes are made observations show great detail observations could include more observations are complete, but observation tables are OBSERVATIONS type of change is accurately detail lack detail incomplete or incorrect Part 2 determined for each test type of change is accurately errors in accurately determining multiple mistakes are made 12 marks determined for each test several types of change measurements and procedures are executed with precision measurements and procedures are executed well caution is taken to limit risk, but precision in measurement is not teacher intervention is required in order to ensure safety caution is taken to limit risk caution is taken to limit risk thoroughly demonstrated lab area and equipment are not LABORATORY TECHNIQUES AND SAFETY 5 marks lab area and equipment are cleaned thoroughly lab area and equipment are cleaned lab area and equipment are left somewhat clean left clean