IIT/FIELD MUSEUM – High School Transformation Project



Ionic and Covalent Bonding Laboratory Investigation

Name______________________________________________________________ Period: ___

1. Purpose: Develop and implement a procedure to observe the properties and discover trends of ionic and covalent compounds.

2. Materials:

• Sodium Sulfate (NaSO4)

• Sodium chloride (NaCl)

• Glucose (C6H12O6)

• Salycilic Acid (C7H6O4)

• Tongs

• PASCO GLX interphase

• Conductivity probe

• Temperature probe

• Hot plate

• Aluminum foil

• 100 mL beakers

• Stirring rod

3. Procedures:

Melting Point Test

1. Pour a small of each compound into an aluminum foil cup (make sure you place the substances in the labeled cup to avoid contamination).

2. Place the aluminum cup on the hot plate and hold a thermometer tip to the dish as it heats (some of the compounds have melting points than cannot be reached by this method, so record the melting points of those compounds as “very high” or “over 180(C.”). Record your data on the data table provided.

3. Remove the aluminum cup from the hot plate using tongs and place on designated area for cooling.

Solubility Test

1. Pour a small amount of each compound into the labeled beaker (make sure to pour each substance in the correct beaker to avoid contamination)

2. Using a squirt bottle add some distilled or deionized water to each beaker.

3. Stir and observe whether the compound dissolves. Record your observations on the data table.

4. If the substance dissolves, test the solution for conductivity.

Conductivity Test

1. Place the conductivity tester in the solution and observe whether the solution conducts electricity (make sure to rinse the conductivity probe in distilled water before testing another solution). Record data on the data table provided.

4. Ionic and Covalent Bonding Data Table

|Compound |Appearance |Melting |Solubility |Conductivity* |

|Salycilic Acid | |140o |No |Did not test |

|C7H6O3 | | | | |

| | | | | |

| | | | | |

|NaCl | |Above 200o |Yes |10,000 |

| | | | | |

| | | | | |

| | | | | |

|C6H12O6 Glucose | |130o |Yes |500 |

| | | | | |

| | | | | |

|Sodium Sulfate | |Above 200o |Yes |7,000 |

|NaSO4 | | | | |

|* Only test for conductivity if the compound tested positive for solubility. |

5. Analysis—Write answers to these questions after performing the lab.

1. What do you think must happen to the attractions between particles in order for a substance to melt?

2. Did all compounds melt at the same temperature?

a. What is similar about those substances that melted and that did not melt?

b. What factors do you think affect melting point based on your answers to 2a?

3. Classify each of the substances you tested as ionic or molecular compounds based on your observations.

4. What are the differences in properties between ionic and molecular (covalently bonded) compounds?

5. Explain why some substances, when dissolved, conduct electricity and some do not.

6. If water is a molecular compound, should it conduct electricity? Explain.

7. Using your results and ideas from today, why should electrical appliances not be used near water?

6. Reading:

From this reading and your lab results create a venn diagram comparing and contrasting ionic and covalent bonds.

| Comparison of Properties of Ionic and Covalent Compounds |

|Because of the nature of ionic and covalent bonds, the materials produced by those bonds tend to have quite different properties.|

|The atoms of covalent materials are bound tightly to each other in stable molecules, but those molecules are generally not very |

|strongly attracted to other molecules in the material. On the other hand, the atoms (ions) in ionic materials show strong |

|attractions to other ions in their vicinity. This generally leads to low melting points for covalent solids, and high melting |

|points for ionic solids. For example, the molecule carbon tetrachloride is a non-polar covalent molecule, CCl4. It's melting |

|point is -23°C. By contrast, the ionic solid NaCl has a melting point of 800°C. |

|Ionic Compounds |

| |

|Crystalline solids (made of ions) |

|High melting and boiling points |

|Conduct electricity when melted |

|Many soluble in water but not in nonpolar liquid |

|Covalent Compounds |

| |

|Gases, liquids, or solids (made of molecules) |

|Low melting and boiling points |

|Poor electrical conductors in all phases |

|Many soluble in nonpolar liquids but not in water |

| |

|You can anticipate some things about bonds from the positions of the constituents in the periodic table. Elements from opposite |

|ends of the periodic table will generally form ionic bonds. They will have large differences in electronegativity and will |

|usually form positive and negative ions. The elements with the largest electronegativities are in the upper right of the periodic|

|table, and the elements with the smallest electronegativities are on the bottom left. |

|Elements which are close together in electronegativity tend to form covalent bonds and can exist as stable free molecules. Carbon|

|dioxide is a common example. |

7. Writing

Use the following prompt to write a clear paragraph using the Fenger Great Paragraph Rubric.

You are a scientist that has been given the task of finding a new material to add strength to the tires of cars. This new material needs to have the ability to withstand a lot of heat, and also has to stay together in the rain. Your employer would also like something that will not conduct electricity if possible. So far you and your colleagues have identified 2 potential substances. The first is NaCl which is an ionic bond. The second is CO2 which is a covalent bond. Neither is going to be a perfect fit. Choose 1 of the 2 and explain why you think it is the BEST fit. Use the properties of ionic and covalent bonds you have identified from the lab and the reading.

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