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Ionic vs. Covalent Compounds (49 Favorites)

LAB in Melting Point, Covalent Bonding, Ionic Bonding, Molecular Structure. Last updated May 24, 2017.


Summary

In this lab, students will compare two seemingly similar substances, salt and sugar. Through melting a sample of each substance and analyze of their chemical composition, students will draw conclusions regarding ionic and covalent compounds.

Grade Level

High School

Objectives

By the end of this lab, students should be able to

  • Observe the melting of sodium chloride and sucrose.
  • Compile a list of characteristics describing sodium chloride and sucrose that could be used to help identify them.
  • Infer properties of ionic and covalent compounds based on their results.

Chemistry Topics

This lab supports students’ understanding of

  • Molecules & Bonding
  • Ionic Bonding
  • Covalent Bonding
  • Molecular Structure
  • Physical Properties
  • Melting Point

Time

Teacher Preparation: 10 minutes

Lesson: 30-40 minutes

Materials

  • Table salt (NaCl) – a pinch
  • Table sugar (C12H22O11) – a pinch
  • Aluminum foil – about 4 inches by 10 inches
  • Candle – table, votive, birthday, tea light, etc.
  • Tongs or suitable alternative – to hold the aluminum over the candle

Safety

  • Always wear safety goggles when handling chemicals in the lab.
  • Students should wash their hands thoroughly before leaving the lab.
  • Always use caution around open flames.Keep flames away from flammable substances.
  • Always be aware of an open flame. Do not reach over it, tie back hair, and secure loose clothing.
  • Open flames can cause burns. Liquid wax is hot and can burn the skin.

Teacher Notes

  • I use this lab experiment as a take home lab assignment. Find out more about my take home labs in the March issue of Chemistry Solutions or in the AACT Webinar archive.
  • The materials are commonly found at home, so have students to check for availability. If this is difficult, allowing students to complete the lab in the classroom before or after school is a good option.
  • You can then use this experiment as an introduction, or as a review opportunity to discuss some of the properties that characterize ionic compounds versus covalent compounds.

For the Student

Objective

  • To observe the melting of sodium chloride and sucrose.
  • To compile a list of characteristics describing sodium chloride and sucrose that could be used to help identify them.

Materials

  • Table salt (NaCl) – a pinch
  • Table sugar (C12H22O11) – a pinch
  • Aluminum foil – about 4 inches by 10 inches
  • Candle – table, votive, birthday, tea light, etc.
  • Tongs or suitable alternative – to hold the aluminum over the candle

Safety

  • Always wear safety goggles when handling chemicals in the lab.
  • Students should wash their hands thoroughly before leaving the lab.
  • Always use caution around open flames.Keep flames away from flammable substances.
  • Always be aware of an open flame. Do not reach over it, tie back hair, and secure loose clothing.
  • Open flames can cause burns. Liquid wax is hot and can burn the skin.

Procedure

  1. Read the entire procedure before you start and make an appropriate data table in the space provided below in order to record your observations.
  2. Prepare 2 small aluminum “boats” for holding your samples of salt and sugar. Be sure to fold up the edges and have a good place for the tongs to grasp the “boat.”
  3. Devise a method for supporting your candle.
  4. Prepare your “boats” by putting a small amount (about 10 crystals) of table salt in one, and the same amount of table sugar in the other.Record your observations about the appearance of each type of crystals in your data table.
  5. Light your candle and then, using tongs, hold the 1st boat over the flame for 2–3 minutes. Record your observations in your data table.
  6. Repeat step 5 with the 2nd boat.
  7. If any sugar is still present at this point, you may continue to heat it and watch how it continues to change.

Data

Create an appropriate data table in order to record your observations:

Analysis and conclusions

  1. List the elements that make up salt and sugar. Identify the type of the elements. (Types include: metals, metalloids, nonmetals)
  2. Which substance seemed to have the lowest melting point?
  3. Salt is considered to be an ionic substance, while sugar is commonly thought of as a covalent (or molecular) substance. Keeping that in mind, if you were given 2 unidentified white crystals and asked to classify them as either ionic or covalent in nature, what steps would you take and what evidence would you look for?
  4. Have your parent sign your work: