ZERO-IN

Italicized font represents information to be shared orally or physically completed with the students at this time.

Non-italicized font represents additional information included supporting the teacher’s understanding of the content being introduced within the CELL.

ASK WHY

Remind students that we live in a world of solutions. The atmosphere is a gaseous solution. The oceans are saline solutions and, even our bodies, are largely aqueous solutions. To understand the world in which we live and the organisms that inhabit it, we need to know about solutions.

BRANCH OUT

Remind students that before pharmacists formulate and dispense medication, they have to consider the chemical and physical aspects of it. Is the medication soluble in a solvent? Is it chemically stable in solution and for how long? Are two or more solutes chemically and physically compatible in solution? How should the product be packaged and stored?

GET FOCUSED

Inform students that the Investigation is designed to help them to answer the following Focus Questions:

• What affects the solubility of a solute? Stirring increases the solubility of a solute.

• Can the rate of solubility of a solute be changed? Yes, the rate of solubility of a solute can be changed by stirring. Stirring increases the rate of solubility of a solute.

Note: These questions are located in students’ SDRs at the beginning and end of the Investigation.

Note: These are succinct responses to the Focus Questions and are placed here for your reference at this time. Fully developed responses to the Focus Questions can be found on the PostLab page.

GO DEEPER

As a class, read the Background(s) in the Investigation. Have students read the information aloud or silently to themselves. When students have finished, discuss the following concepts as a class:

• Forces between the particles of a solute attract each other and hold them together.
• Forces between the particles of the solvent also attract each other and hold them together.
• When a solute dissolves, solvent particles surround the solute particles and destroy the forces holding them together.
• As the solvent particles surround the solute particles, the forces holding the solvent particles together are also destroyed.
• When the solute is completely dissolved, new forces have formed between the solute and solvent particles holding them together to form a solution.
• Different solutes require different lengths of time to dissolve. This is called the rate of solubility.
• The rate depends on how fast the solvent particles are able to surround the solute particles. It also depends on how fast the forces between the solute and solvent particles are formed.
• The rate of solubility is defined as how much mass of a solute can be dissolved in a certain amount of time. It is written as the mass in grams divided by the time in minutes required for the solute to dissolve.

Note: These concepts are integrated into the Background(s) and are used to deepen students’ comprehension of the big ideas.

LEARN THE LabLearner LINGO

The following list includes Key Terms that are introduced in the Investigation Background(s). They should be used, as appropriate, by teachers and students during everyday classroom discourse.

• properties
• rate

Note: Definitions to these terms can be found on the Introduction page to the CELL.

Note: Additional words may be bolded within the Background(s). These words are not Key Terms and are strictly emphasized for exposure at this time.

SET FOR SUCCESS

• Direct students to complete the Recall section in their SDRs. Student answers may vary.

• • What is solubility?
  • Can you change how solute particles and solvent particles interact?
  • Will a solute always require the same amount of time to dissolve in a solvent?

• Explain to students that they will be using the same compounds that were used in Investigation One to test the effect of stirring on the rate of solubility.
• Play the video below. Stop to ask students questions or answer students’ questions when necessary. Remind students to follow along with their SDRs and make any notes that they think might be helpful.
• After the video, direct students to divide into their lab groups to discuss their strategy for the lab. For example, they may assign certain group members to perform specific functions during the lab.

Note: The purpose of the video is to allow students to anticipate the laboratory experience they will soon encounter. Students should leave this PreLab session with a firm idea of what to expect and how to perform in the lab.

Note: Homework is posted below the video.