This is a series of experiments, PhET Interactive Simulation activities, and clicker questions to relate macroscopic and molecular representations of homogenenous solutions. Graphing skills are also used.

Materials

Access to PhET Inteactive Simulations -

Activity 1 Sugar and Salts 

Activity 2 Molarity 

Lab 1: Sugar, Salt, water, Graduated cylinders, Excel or graphing program or graph paper

Lab 2: I chose the nickel salt because I had a large supply and it has a nice color. I did not

worry that it might not totally dissolve, but just wanted to make sure it was colored and that

dilution would look very different. You could use any number of chemicals and perhaps one that

is more soluble. My jar was full and had not been used in 15 years, so it seemed a good use. 

Background

This series of exercises is meant to introduce solutions to students with little background. For more advanced students, parts could be skipped.

Procedure

See the attached pdf. 

Questions

See the Teacher pdf or http://phet.colorado.edu/en/contributions/view/3745 to get the Powerpoint versions. 

Concepts

PhET Activity 1

Learning Goals: Students will be able to:

• Identify if a compound is a salt or sugar by macroscopic observations or microscopic representations.
• Explain how using combinations of solutes changes solution characteristics or not.
• Use observations to explain ways concentration of a solute can change.
• Describe ways the formula, macroscopic observations, or microscopic representations of a compound indicates if the bonding is ionic or covalent.

Lab 1: Determine the solubility of table salt and table sugar in room temperature water using varying amounts of water.

PhET Activity 2:

Learning Goals: Students will be able to

• Determine the solubility for some solutes and explain why the solubility cannot be determined for others given experimental constraints.
• Identify the relationships for measurable variables by designing quantitative experiments, collecting data, graphing, and using appropriate trend lines.

Lab 2: 

• Determine the amount of grams of solute to make a given volume of specified molarity.
• After dilution, determine the molarity of a solution.

Time Required

This is a combination of activities that will take several class periods or a few class periods and homework if students have computer access outside of classtime. 

Preparation

Both labs require little preparation if you have standard chemical lab equipment. The PhET activities require the use of computers with Java installed. The simulations can be run online or downloaded onto the comuters in advance of the class.

Attribution

PhET Interactive Simulations and the activities written by a PhET team member (which I am) are licensed under Creative Commons and may be used or adapted. 

Credits