Initial Observations and Student Inquiries Based upon Properties of Matter – Lesson 18: Changing Mixtures Addresses State Standards Sci 6-8 PS2B, Sci 6-8 INQA, and Sci 6-8 INQD (Original ideas from Ramey and Wong – 2006)

Goals Participants will describe the process of making ice cream and develop an experiment using the scientific method to test a research question. Know: How ice cream is made and how does table salt effect pure water. Do: Develop an experiment to test a hypothesis. Engage: Page Keeley Assessment Probe Explore: Difference between purified water and tap water – Boiling Points and Freezing Points Explain: Boiling and Freezing Water Lab Activities Elaborate: We All Scream For Ice Cream–Inquiries in Aqueous Table Salt Solution and Making Ice Cream Evaluate: Translating Kinetic Molecular Motion from an Ice Cream Perspective Debrief

From Uncovering Student Ideas in Physical Science by Page Keeley and Rand Harrington, Vol 2 - page 53

Crumple your papers and throw them to the middle of the room. Retrieve someone else’s paper from the center of the room...if it is yours, then crumple and throw it in again. Align yourself within the room according to the answer on the paper you picked up: A, B, or C Align yourself in regards to whether YOU AGREE, DISAGREE, or DON’T KNOW with the answer. CONSIDER THAT THE WATER IS NOT PURE BUT IS TAP WATER INSTEAD: DO YOU THINK THE TAP WATER WOULD BEHAVE IN THE SAME MANNER AS THE PURE WATER? WHAT ABOUT THE FREEZING POINT OF EITHER PURE OR TAP WATER?

Let’s observe the boiling point temperatures of Wenatchee Tap Water and Deionized/Distilled Water from the local convenience store. What do you observe? Differences List Similarities List

Perform the Boiling Water Activity PARTICIPANTS SHARE OUT TO CLASS Perform the Freezing Water Activity PARTICIPANTS SHARE OUT TO CLASS

A solution is made up of at least two components: Solvent – the major component in a solution Solute(s) – the dissolved component(s) in a solution High School Chemistry Knowledge Alert: A homogeneous mixture of solute and solvent particles that may or may not have covalent, polar, or ionic molecular interaction.

…when there are observed changes in physical properties of a pure solvent due to a collection of dissolved solute particles within the entire solution. High School Chemistry Knowledge Alert: Colligative Properties are not due to a CHEMICAL CHANGE. Colligative properties are due to the collection of dissolved solute particles that make small PHYSICAL CHANGES to the physical properties of the solvent! Tim Sorey definition with slight adjustments to “Atoms First” from McMurry and Fay, 2010

Where do I observe “Colligative Properties”?

Boiling-point elevation Freezing-point depression Vapor pressure Osmotic pressure

Solutions have different properties than either the pure solvent or the solute. For example, a solution of sugar in water is neither crystalline like sugar nor tasteless like water. Some of the properties unique to solutions depend only on the number of dissolved particles and not their identity. Such properties are called colligative properties.

Perform the Ice Cream Inquiries Experiment SHARE OUT Experiments/Experiences AS CLASS

Perform the Ice Cream Inquiries Experiment SHARE OUT Experiments/Experiences AS CLASS Colligative Properties MACRO Simulator: ojectfolder/flashfiles/propOfSoln/colligative.html ojectfolder/flashfiles/propOfSoln/colligative.html and /faq/why-salt-melts-ice.shtml /faq/why-salt-melts-ice.shtml

Perform the Ice Cream Inquiries Experiment SHARE OUT Experiments/Experiences AS CLASS Colligative Properties MACRO Simulator: ojectfolder/flashfiles/propOfSoln/colligative.html ojectfolder/flashfiles/propOfSoln/colligative.html and /faq/why-salt-melts-ice.shtml /faq/why-salt-melts-ice.shtml Practical Applications Melting ice on your sidewalk Cooking your pasta noodles

From Uncovering Student Ideas in Physical Science by Page Keeley and Rand Harrington, Vol 4 – page 45

Crumple your papers and throw them to the middle of the room. Retrieve someone else’s paper from the center of the room..if it is yours, then crumple and throw it in again. Align yourself within the room according to the answer on the paper you picked up: A, B, or C Align yourself in regards to whether YOU AGREE, DISAGREE, or DON’T KNOW with the answer.