Initial Observations and Student Inquiries

Based upon Properties of Matter – Lesson 18: Changing MixturesAddresses State Standards

Sci 6-8 PS2B, Sci 6-8 INQA, and Sci 6-8 INQD

(Original ideas from Ramey and Wong – 2006)

We All Scream for Ice Cream: Colligative Properties of Matter

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 ProbeExplore: Difference between purified water and tap water –

Boiling Points and Freezing PointsExplain: Boiling and Freezing Water Lab ActivitiesElaborate: We All Scream For Ice Cream–Inquiries in Aqueous

Table Salt Solution and Making Ice CreamEvaluate: Translating Kinetic Molecular Motion from an Ice

Cream PerspectiveDebrief

Outline

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

Engage: What do you think?

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?

Engage: What do you think?

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 ListSimilarities List

Explore : Difference between purified water and tap water

Perform the Boiling Water ActivityPARTICIPANTS SHARE OUT TO CLASS

Perform the Freezing Water ActivityPARTICIPANTS SHARE OUT TO CLASS

Explain: Boiling and Freezing Water LAB Activities

SolutionA solution is made up of at least two components:

Solvent – the major component in a solutionSolute(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.

Colligative Properties…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!

SAY WHAT?Where do I observe “Colligative

Properties”?

http://www.uni.edu/%7Eiowawet/H2OProperties.html

Colligative Properties

Boiling-point elevationFreezing-point depressionVapor pressureOsmotic pressure

Colligative Properties – Still struggling?Where the rubber hits the road…

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.

http://www.sparknotes.com/chemistry/solutions/colligative/summary.html

Perform the Ice Cream Inquiries ExperimentSHARE OUT Experiments/Experiences AS

CLASS

Elaborate: We All Scream For Ice Cream

Perform the Ice Cream Inquiries ExperimentSHARE OUT Experiments/Experiences AS

CLASS

Colligative Properties MACRO Simulator:http://group.chem.iastate.edu//Greenbowe/secti

ons/projectfolder/flashfiles/propOfSoln/colligative.html

andhttp://antoine.frostburg.edu/chem/senese/101/s

olutions/faq/why-salt-melts-ice.shtml

Elaborate: We All Scream For Ice Cream

Perform the Ice Cream Inquiries ExperimentSHARE OUT Experiments/Experiences AS

CLASS

Colligative Properties MACRO Simulator:http://group.chem.iastate.edu//Greenbowe/secti

ons/projectfolder/flashfiles/propOfSoln/colligative.html

andhttp://antoine.frostburg.edu/chem/senese/101/s

olutions/faq/why-salt-melts-ice.shtml

Practical Applications Melting ice on your sidewalkCooking your pasta noodles

Elaborate: We All Scream For Ice Cream

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

Evaluate: What do you think?

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.

What do you think?