Lab: Differences between Ionic and Covalent Compounds



Lab: Differences between Ionic and Covalent Compounds Section 2.2

 

Properties such as melting point, boiling point, solubility, electrical conductivity, and odor are some of the properties that can be used to distinguish ionic from covalent compounds. In this experiment, you will observe several properties of some ionic and covalent compounds. You will use your observations to classify four compounds as either ionic or covalent.

1. What are the general characteristics of Ionic Compounds in terms of melting point, boiling point, solubility, electrical conductivity, and odour?

2. What are the general characteristics of Covalent Compounds in terms of melting point, boiling point, solubility, electrical conductivity, and odour?

 

Purpose:  To recognize patterns among the properties of ionic and covalent compounds that will help you to distinguish between the two substances.

 

Materials:

4 beakers                                                                    

Conductivity apparatus                              

4 glass rods

sodium chloride                                                                            

potassium iodide                                                                       

sugar                                                                                             

naphthalene                                                                                

Distilled Water

 

Procedure:

 

Part A: Physical Properties

1. Label each small beaker with the name of the 4 solids that you will test. Obtain a sample of each compound to be tested. (Take one spoonful only.)

2. Examine each of the compounds and list their physical properties: odour, color, and form. Record your observations in the chart provided.

 Part B: Solubility

1. Place 10 mL of distilled water into each of your sample beakers.

2. Stir vigorously with a glass rod. If the substance dissolves, it is soluble; if not, it is insoluble. Record the results in your observation table.

3. Retain the samples for the next test

 

 

Part C: Electrical Conductivity

1. Use the conductivity tester to determine if each solution conducts electricity.

2. Record your results.

 

Part D: Melting Point

Research the melting point of each substance and record in the table.

|Name of Compound |Physical Properties |Solubility |Electrical Conductivity |Melting Point |

| | | |(solution yes or no) |(°C) |

|Sodium Chloride | | | | |

|Potassium Iodide | | | | |

|Sugar | | | | |

|Naphthalene | | | | |

Observations Record any qualitative observations in a clear, precise manner as you are doing this experiment:

 

Analysis and Conclusions 

1. Use the general characteristics of ionic and covalent substances to classify each substance as ionic or covalent. Explain your rationale. Next calculate the END and determine if your calculation agrees with your classification.

|Compound |Ionic or Covalent |Rationale |ΔEN |Agreement? |

|Sodium Chloride | | | | |

|Potassium Iodide | | | | |

|Sugar | | | | |

|Naphthalene | | | | |

2. How well were you able to classify the compounds using your observations?

 

3. Are general characteristics considered to be true all the time?

4. Why are some covalent compounds considered polar?

5. Explain why ionic compounds are able to conduct electricity.

6. Predict the following:

a) solubility of sodium iodide in water

b) melting point of sodium iodide

c) electrical conductivity of a solution of chlorine gas

d) Whether or not Chlorine gas has an odour

e) How brittle solid PCl3 would be

f) Which has a greater boiling point HCl or HF

g) Which has a greater melting point H2 or HCl

7. Why is distilled water used in Part B?

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