CHEMISTRY NOW: Solubility and Bonding (Grades 9-12) Print

Objective:

Students will investigate the solubility of substances in a polar solvent (water) and a nonpolar solvent (turpentine). Students will design and carry out an investigation to compare the type of bonding in a substance to its solubility in a polar or nonpolar solvent. Students will use their data and observations to draw conclusions about the solubility of a substance and its polarity.


Introduction Notes:

CHEMISTRY NOW: Solubility and Bonding

 

Subject Area: Chemistry

Grade Level:  High School Chemistry

Lesson Title:  Solubility and Bonding

National Science Education Standards:

 Science as Inquiry: 9–12

     Structure and Properties of Matter: 912

     Chemical Reactions: 912

 

Suggested Prior Knowledge: concepts of covalent and ionic bonding; polarity; solubility; solutions

 

Purpose: To understand the relationship between types of bonding, polarity, and solubility

 

Key Vocabulary:  

covalent bond—bond between two atoms involving the sharing of one or more electron pairs

dissolve—the process in which a solute interacts with a solvent to form a solution: particles of the solute are broken apart into individual molecules or ions, and surrounded by solvent particles

ionic bond—bond between two or more oppositely-charged ions formed when electrons are transferred

nonpolar molecule—molecule with an even distribution of charge

polar molecule—molecule with an uneven distribution of charge

solubility—quantity of a solute that will dissolve in a given quantity of solvent

solute—substance dissolved in a solution

solution—homogeneous mixture of a solute dissolved in a solvent

solvent—substance that dissolves the solute in a solution

Objectives:

  1. Students will investigate the solubility of substances in a polar solvent (water) and a nonpolar solvent (turpentine).
  2. Students will design and carry out an investigation to compare the type of bonding in a substance to its solubility in a polar or nonpolar solvent.
  3. Students will use their data and observations to draw conclusions about the solubility of a substance and its polarity.

Materials:

- Safety goggles

- 100 ml beakers (one for each solvent)

- Test tubes

- Test tube rack

- Droppers

- Wooden coffee stirrers

- Water

- Turpentine (or lamp oil)

- Various known solutes (see attached list); label these with chemical formulas

- Several solutes of composition unknown to the students; label these as A, B, C, etc.

 

Procedure:

1. Review briefly with students the types of bonding (covalent, polar covalent, nonpolar covalent, and ionic) and solutions. Begin with a leading question, and follow up:

      How can we determine the type of bonding in a compound from its chemical formula?

      How do the physical and chemical properties of polar covalent and nonpolar covalent bonds compare?

      How do the physical and chemical properties of ionic and covalent bonds compare?

      How do nonpolar and polar substances compare?

 

2. Work with students to design a valid investigation, similar to the one outlined in this lesson plan, to determine which kinds of solutes will dissolve in which solvent. Water will be the polar solvent and turpentine the nonpolar solvent. Guide students to develop a procedure to determine which kinds of bonding allow a substance to dissolve in each solvent (polar / nonpolar).

 

3. Work with students to develop questions to investigate or a hypothesis to test. Ensure that students outline the steps of their procedure carefully and include proper safety procedures. Students should develop an appropriate data table so that they can organize their work. Encourage them to use small quantities of all substances: 5 ml of the solvents, and a small scoop (using coffee stirrer for solid solutes) or a few drops (for liquid solutes). Some leading questions for this step include the following:

      How do we decide if a compound dissolves in a solvent?

      How can we determine if a compound does not dissolve in a solvent?

      Can we make some predictions, based on what we already know about solutions in our everyday lives, about what types of substances will dissolve in water? In turpentine?

 

4. Once students have developed and written their initial procedures (and the teacher has approved them), they can carry out their investigations. The data they gather can then be used to help them determine the type of bonding in the unknown solutes. Turpentine should only be used in a well-ventilated room.

 

5. Lab safety equipment should be used, and safety protocols should be followed. Turpentine should be used in a well-ventilated area and kept away from open flames. If lamp oil is substituted, it should also be kept away from open flames. Solid iodine crystals should be handled with tweezers and used in a hood. Avoid inhaling fumes of iodine (it sublimes) and contact with eyes, skin, or clothing.

 

6. General Procedure that could be used:

a. Obtain a sample of each solvent in a beaker and carefully label these beakers.

b. Obtain a small sample of each known solute to test.

c. For each known solute, use the chemical formula and possibly a Lewis structure to determine the type of bonding present (covalent, nonpolar covalent, polar covalent, or ionic) and the polarity (polar or nonpolar) of the compound.

d. For each solute, predict whether it will dissolve in water (polar solvent) or turpentine (nonpolar solvent).

e. Set up two test tubes for each solute to be tested, one test tube for each solvent. Label each test tube with the solute and solvent to be used.

f. Place a small amount (a few drops or a small scoop) of each solute into the appropriately labeled test tubes.

g. Add a few ml of water to the appropriate test tubes and a few ml of turpentine to the others and observe.

h. Stir the contents of each test tube with a clean coffee stirrer. Record whether the solute dissolves.

i. An appropriate data table might look like this:

 

Solute

Bonding type

(C, PC, or I)

Polarity

(P or NP)

Predicted solubility (W or T)

Experimental solubility observations

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

j. After gathering the data about the known substances, students should use the data to draw conclusions about solubility of a compound in different solvents and the type of bonding in a compound. They can use the knowledge they have gained to determine whether each unknown solute is polar or nonpolar, based on its solubility in water and turpentine.

k. Dispose of all waste materials in designated containers as directed by the instructor. More information on safety and proper disposal methods is available in the additional resources.

 

 

 

7. After the students have finished their investigations, they may present their findings to their classmates and compare their results with those of their classmates. They should be able to explain the phrase “like dissolves like,” using their results. They can also compare their results for each unknown solute with the teacher’s accepted results to see if they were successful in identifying the solutes as polar or nonpolar.

 

Possible known and unknown solutes:

Solute

Polar or Nonpolar

Soluble in

Paraffin (candle wax, CnH2n+2)

Nonpolar

Turpentine

Table salt (NaCl)

Polar

Water

Mineral oil

Nonpolar

Turpentine

Isopropyl alcohol (C3H7OH)

Polar

Water

“Lite salt” (KCl)

Polar

Water

Vegetable oil ((CnH2n+1)COOH)

Nonpolar

Turpentine

Baking soda (NaHCO3)

Polar

Water

Peanut butter

Nonpolar

Turpentine

Table sugar

Polar

Water

Glycerol (C3H5(OH)3)

Polar

Water

Sulfur powder

Nonpolar

Turpentine

Iodine

Nonpolar

Turpentine

Tea (loose or in tea bag)

Polar

Water

Instant coffee

Polar

Water

Sunblock lotion

Nonpolar

Turpentine

Food coloring

Polar

Water

 

Additional Resources:

         http://www.flinnsci.com/Sections/Safety/safety.asp

         http://www.flinnsci.com/search_MSDS.asp

         http://www.flinnsci.com/Documents/MSDS/IJ/Iodine.pdf

         http://www.flinnsci.com/Documents/MSDS/T/Turpentine.pdf

         http://www.daviddarling.info/encyclopedia/P/polarmol.html

         http://answers.yahoo.com/question/index?qid=20080225123318AAbREZ1

         http://en.wikipedia.org/wiki/Solubility

         http://www.chemguide.co.uk/atoms/bonding/ionic.html#top

         http://chemistry.about.com/od/chemistryglossary/a/covalentbonddef.htm

 

 

 

 

 

 

 


Student Worksheet for Solubility and Polarity

 

Experiment Title: ____________________Date: __________Name: __________________

 

Student Hypothesis or Question:

 

_______________________________________________________________________

 

Materials:

 

________________________________________________________________________

 

Safety Precautions:

 

________________________________________________________________________

 

________________________________________________________________________

 

________________________________________________________________________

 

Procedure:

 

Wear Safety Goggles for all lab work.

________________________________________________________________________

________________________________________________________________________

________________________________________________________________________

________________________________________________________________________

________________________________________________________________________

________________________________________________________________________

________________________________________________________________________

________________________________________________________________________

________________________________________________________________________


Data and Observations:

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Analysis of Data:

________________________________________________________________________

________________________________________________________________________

________________________________________________________________________

________________________________________________________________________

________________________________________________________________________

________________________________________________________________________

 

Conclusions:

________________________________________________________________________

________________________________________________________________________

________________________________________________________________________

 

 

Close NBC Learn

FILTERING

If you are trying to view the videos from inside a school or university, your IT admin may need to enable streaming on your network. Please see the Internet Filtering section of our Technical Requirements page.

DVDs AND OTHER COPIES

Videos on this page are not available on DVD at this time due to licensing restrictions on the footage.

DOWNLOADING VIDEOS

Subscribers to NBC Learn may download videos and play them back without an internet connection. Please click here to find out more about subscribing or to sign up for a FREE trial (download not included in free trial).

Still have questions?
Click here to send us an email.

Close NBC Learn

INTERNATIONAL VISITORS

The Science of the Olympic Winter Games videos are only available to visitors inside the United States due to licensing restrictions on the Olympics footage used in the videos.

FILTERING

If you are trying to view the videos from inside a school or university, your IT admin may need to enable streaming on your network. Please see the Internet Filtering section of our Technical Requirements page.

DVDs AND OTHER COPIES

The Science of the Olympic Winter Games is not available on DVD at this time due to licensing restrictions on on Olympic footage.

DOWNLOADING VIDEOS

Subscribers to NBC Learn may download videos and play them back without an internet connection. Please click here to find out more about subscribing or to sign up for a FREE trial (download not included in free trial).

Still have questions?
Click here to send us an email.

Close NBC Learn

Choose your product

NBC Learn K-12 product site
NBC Learn Higher Ed product site

For NBC Learn in Blackboard™ please log in to your institution's Blackboard™ web site and click "Browse NBC Learn"

Close NBC Learn

If you have received a new user registration code from your institution, click your product below and use the "Register now" link to sign up for a personal account.

NBC Learn K-12 product site
NBC Learn Higher Ed product site

For further assistance, please contact our NBC Learn Support Team and we'll be happy to assist you.

Start Your Free
day
Day Trial!