ScienceSource.ca Dry Lab Activity

Unit B - Chapter 6

Investigating Science 9

Inquiry Activity

Shape Up!

Skills Reference 2

Skills you Will Use

  • Using appropriate equipment and tools
  • Drawing conclusions

Safety

  • Gloves

Caution

In this lab you will be using hot water. Use a thick glove or gloves to protect yourself from burns.

In an ionic compound, positive and negative ions attract each other, with all the positive ions attracted to all of the negative ions, forming ionic bonds. Ionic bonds cause ions to group together in an alternating pattern of charged particles called a crystal arrangement.

In this activity, you will investigate the formation of salt crystals to find evidence of ionic compound crystal arrangement.


Question

What is the structure of sodium chloride crystals?


Materials and Equipment

  • sodium chloride (NaCl)
  • plastic spoon
  • two Petri dishes
  • black paper
  • 100-ml graduated cylinder
  • 250-ml beaker
  • hot water
  • hand lens

Dry Lab

A "dry lab" activity includes collected data and/or a video solution for your convenience. You can simply watch the following video and use the provided data, or if you wish to perform this lab for yourself, follow the procedure steps 1 through 8 described in the video. The same steps are included in written form in the documents available for download on the bottom of this page.



Analyzing and Interpreting

  1. What do your observations tell you about the crystal structure of NaCl and crystal arrangement of ionic compounds in general?

Forming Conclusions

  1. A student performing the procedure steps 1 through 8 recorded the following observations and results. What do these results indicate about the crystal structure of NaCl and crystal arrangement of ionic compounds in general? Explain your answers.

    Substance

    Observations

    Original NaCl crystals

    White, granular, square-shaped crystals

    NaCl solution

    Slightly cloudy solution

    New NaCl crystals

    White, granular, square-shaped crystals stuck together, some residue



  2. A student placed a NaCl crystal under a dissecting microscope and observed the following image of a square-shaped crystal. Does this image make sense according to what you know about the ionic bonding of sodium chloride? Explain.