Unit 2 Day 3

Physical & Chemical Weathering

Warm-Up• Imagine dropping a sugar cube into a cup of coffee and

the same sugar cube into a cup of cold lemonade. 1) In which cup do you predict the sugar cube will dissolve

first? Why?2) What could you do to make the sugar cube dissolve faster?3) Stretch your mind: You know what the rock cycle is. What

do you think drives the rock cycle?! –Candy!

• Daily Goal: SWBAT explain differences in chemical and physical weathering.

Key Terms• Physical Weathering• Chemical Weathering• Biological Activity• Unloading• Frost Wedging

Agenda

• Warm Up• HW Check• Weathering Lab• Notes: Weathering• Weathering video + Real-world application• Smarties demo, if time…• Exit Ticket

Weathering…why do we care?Weathering steels are high strength, low alloy

steels that can provide corrosion protection without additional coating. Increase in alloying elements, primarily copper, stops atmospheric corrosion in the material itself.

The material was developed in the 1930s for use in coal hopper train cars to resist the corrosive effects of the sulfur in coal and exposure to long periods of rain. Experience at the time found that conventional steel was corroding in relatively short periods of time. What sets the material apart from conventional steel is in the chemistry. Weathering steel will have a minimum copper content of at least 0.20 percent, whereas conventional carbon steels have a copper content of less than .02 percent

Physical Weathering Video

• While you watch, write down at least 3 BULLETED NOTES below your DO NOW

• http://player.discoveryeducation.com/index.cfm?guidAssetld=3AD9D2D9-95D5-4D4C-905D-092C58795462&blnFromSearch=1&productcode=DSCE)

Weathering Lab PROBLEM: How does the environment affect the rate of chemical weathering?

RESEARCH: Use your notes and page 129-131 in the text book to answer the following questions: 1) What is chemical weathering?

2) What is physical weathering?

3) How does chemical weathering differ from physical weathering? 4) What are some factors that affect the rate (speed) of chemical weathering?

10 minutes!

HypothesisHypothesis

At which temperature will chemical weathering occur the fastest? (If…then)

Make an educated guess based on the research you’ve already done!

Experiment: Part 1Experiment: Part 11. Fill the container of rocks about half full with water. Make

Observations about the water, container, and rocks.

2. Place the lid on the container and shake the container vigorously 100 times.

3. Pour your water, but not your rocks into your beaker.

4. Make observations of the water in the beaker and the sides of the plastic container after shaking.

5. Pour the rest of your water back into the plastic container and begin part 2.

Part 1 ObservationsBefore Shaking After Shaking

Experiment: Part 2Experiment: Part 2

Temperature 10-20oC 20-30oC 30-40oC 40-50oC

Where will this water

most likely come from?

Where will this water

most likely come from?

What might you need to use to get to the

proper temperature?

What might you need to use to get to the

proper temperature?

Sharing your data…

Starting Temperature (oC)

Dissolving Time (seconds)

Final Temperature (oC)

Average Temperature

DataData Title: ____________________________________________

Analysis and ConclusionAnalysis and ConclusionUse your data and observations to complete your

analysis and conclusion (15 minutes)

**I SHOULD HEAR ONLY TALK ABOUT THIS LAB!

**YOU SHOULD BE WORKING AND COLLABORATING with your lab group.

Let’s take a deeper look…

Frost WedgingFrost WedgingWhen water When water freezes and expands, freezes and expands, it enlarges cracks in it enlarges cracks in rocks.rocks.

What happens when you freeze a coke can?

• The liquid expands, and often times the can will bust!

Chemical WeatheringChemical WeatheringBiological ActivityBiological Activity

UnloadingUnloadingFrost WedgingFrost Wedging

Devil’s Tower, Wyoming

• First National Monument– Devils Tower was the first declared United States

National Monument, established on September 24, 1906 by President Theodore Roosevelt.

• What is it?– Devils Tower is a monolithic igneous intrusion, or

in other words, it is the core of a volcano exposed from erosion

• How do you think Devil’s Tower formed?

HOMEWORK

• Begin silently working on the homework (Questions at the end of the lab worksheet)

Exit Ticket1) In which type of climate would chemical weathering occur the fastest?

A. warm and dry C. warm and wetB. cold and dry D. cold and wet

2) Which of the following are not a type of mechanical weathering?A. Uploading B. Biological Activity C. Cutting D. Frost Wedging

3) We learned from the lab today that as the temperature increases, the rate of chemical weathering ________.A. increases B. decreases C. stays the same D. increases then decreases

4) Students placed rock chips of uniform size and shape in jars half-filled with water and shook themfor different lengths of time. One rock chip was collected for each length of shaking and displayed. Which column above shows the rock chips arranged from top to bottom in order of least to most shaking time? Explain your reasoning.