Properties of Ionic & Covalent Compounds PURPOSE To Measure and observe properties of various substances To arrange the substances into groups on the basis of their properties To learn the properties of ionic and covalent substances. BACKGROUND Chemical compounds are combinations of atoms held together by chemical bonds. These chemical bonds are of two basic types: IONIC & COVALENT Ionic bonds result when one or more electrons from one atom or group of atoms are transferred to another atom. Positive and negative ions are formed, these are attracted to each other. In covalent compounds the electrons are shared by the bonded atoms. The physical properties of a substance such as melting point, solubility and conductivity tell us a lot about the type of bond in a compound. In this experiment, you will conduct tests on the properties and compile data enabling you to classify compounds as ionic or covalent. MATERIALS 50ml. Beaker Sucrose 8 x Test tubes Citric Acid Bunsen Burner Potassium Iodide Test Tube tongs Sodium chloride Multi Meter Ethanol Battery Holder Distilled water Connecting Leads

Properties of Ionic & Covalent Compounds A. DESCRIPTION Record a detailed description of each substance in your data table. Your observations should be extensive B. MELTING POINT Place a few crystals (approx. 5 – 10) of one substance into a clean test tube. Hold the test tube in a blue flame over the Bunsen burner. Time how long the crystals take to melt. HEAT FOR 2 mins. ONLY. Do NOT change the flame on the Bunsen Burner Remove the substances that melt immediately. Record the time taken in your results table. Including anything that doesn’t melt. C. SOLUBILITY Place a few crystals (approx. 5 – 10) of one substance into a clean test tube. Add 10-15 drops of WATER and gently agitate the test tube for 3-5 mins. Record your observations Repeat this for all four substances KEEP THESE SOLUTIONS FOR THE CONDUCTIVITY TEST. REPEAT Make sure you use a clean DRY test tube for each substance before adding the ethanol Place a few crystals (approx. 5-10) of one substance into a clean test tube. Add 10-15 drops of EHANOL instead of water and gently agitate for 3-5 minutes. MAKE SURE TEST IS IDENTICAL WITH THE SAME NUMBER OF CRYSTALS AND THE SAME NUMBER OF DROPS OF LIQUID – Water or Ethanol D. CONDUCTIVITY Using the solution (the one with water) from the solubility test pour it into a 50ml beaker. Make the solution up to 20ml using the distilled water and the measure on the side of the beaker . Connect the banana plugs to the multi meter. Next connect the alligator clips to the carbon rods a place the carbon rods in the solution Make sure the carbon rods aren’t touching. Record the reading on the multi meter. Repeat this for all four substances and record your observations.

Properties of Ionic & Covalent Compounds PRE-LAB QUESTIONS Define the terms covalent bonding and ionic bonding. In part ‘B’ , why do you NOT alter the Bunsen burner flame when measuring the time take to reach melting point? During which procedure should the bunsen Burner be lit and how long should it remain lit? In part ‘C’, why should you make sure the test using ethanol uses a clean and DRY test tube for each substance? Classify the properties to be tested (description, melting point, solubility and electrical conductivity) as PHYSICAL or CHEMICAL properties.

Properties of Ionic & Covalent Compounds RESULTS AND POST-LAB. QUESTIONS Using the physical property of solubility in water separate the compounds into 2 groups GROUP 1 GROUP 2 Soluble in Water Insoluble in Water 2. What other physical properties do these groups have in common? 3. Which compounds do not share all the physical properties of these groups? Name the compounds and the unshared physical property? 4. Separate the compounds into 2 groups based on the type of compound i.e . ionic or molecular. IONIC MOLECULAR Describe the general physical properties for ionic compounds. Describe the general physical properties for molecular compounds. Using your data, which physical property best separates the compounds into ionic or molecular? Using your data, which physical property is least helpful in separating the compounds into ionic or molecular? WHY? List the physical properties you would predict the following compounds to have. methane – CH4 acetic acid – HC2H3O2 copper (II) sulphate – CuSO4

Properties of Ionic & Covalent Compounds Name:………………………………………………………………………… Date:……………………. Compound Description Melting Point/Time Solubility Water Ethanol Conductivity Record the value Citric Acid C6H8O7 Sodium Chloride NaCl Potassium Iodide KI Sucrose C12H22O11