1. The chef at the “Chemical Café” wants to add new items to the menu, but only items that represent a chemical change can be added. Decide if each menu item represents a chemical change and tell why or why not.

2. Is this a chemical change? Why or why not?
We begin with a plain white piece of bread and heat it until it turns brown and produces a delightful smell. Is making toast a chemical change?
Lovely fresh oranges are hand squeezed until the delicious juice drips into your glass. Is making orange juice a chemical change?

3. Is this a chemical change? Why or why not?
3. Grade A eggs are cooked until they are light, fluffy, and yellow. Is making scrambled eggs a chemical change? 4. We begin with strawberries, ice, sugar, and milk. We blend them together to make a thick, delicious drink. Is making a strawberry smoothie a chemical change?

4. Is this a chemical change? Why or why not?
5. We mix together the finest fresh nuts and dried fruit to create this tasty blend of trail mix. Is making trail mix a chemical change? 6. Creamy buttermilk, baking powder, flour, butter, and salt are mixed together and baked until gas bubbles cause them to rise. The batter turns into flaky, golden brown biscuits. The aroma of the baked biscuits is delightful. Is making buttermilk biscuits a chemical change?

5. Is this a chemical change? Why or why not?
7. We freeze our finest orange juice until the orange liquid becomes a tasty, frozen solid. Is making orange-sicles a chemical change? 8. Fresh milk is combined with special enzymes until the milk becomes thick and clumpy with a completely new taste and smell. Is making cottage cheese a chemical change?

6. Is this a chemical change? Why or why not?
9. Fresh pineapple, strawberries, kiwi, and blueberries are sliced and mixed together to make this sweet treat. Is making fruit salad a chemical change? 10. Fluffy white marshmallows are toasted over an open flame until they begin to turn golden brown and smell heavenly. Is making toasted marshmallows a chemical change?

7. New items on the “Chemical Café” menu are…
1. Toast
3. Eggs
6. Buttermilk biscuits
8. Cottage cheese
10. Toasted marshmallows

8. Which type of weathering is it?
Mechanical or Chemical

9. Mechanical or Chemical Weathering?

10. Mechanical or Chemical Weathering?

11. Mechanical or Chemical Weathering?

12. Mechanical or Chemical Weathering?

13. Mechanical or Chemical Weathering?

14. Mechanical or Chemical Weathering?

15. Mechanical or Chemical Weathering?

16. Mechanical or Chemical Weathering?

17. Mechanical or Chemical Weathering?

18. Mechanical or Chemical Weathering?

19. Mechanical or Chemical Weathering?

20. Mechanical or Chemical Weathering?

21. Mechanical or Chemical Weathering?

22. Mechanical or Chemical Weathering?

23. Mechanical or Chemical Weathering?

24. Mechanical or Chemical Weathering?

25. Mechanical or Chemical Weathering?

26. Mechanical or Chemical Weathering?

27. Mechanical or Chemical Weathering?

28. Mechanical or Chemical Weathering?

29. Mechanical or Chemical Weathering?

30. Mechanical or Chemical Weathering?

31. Mechanical or Chemical Weathering?

32. Mechanical or Chemical Weathering?

33. Mechanical Weathering – Thermal expansion
Thermal Expansion and Contraction - heating causes rock to expand, cooling results in contraction; different minerals expand and contract at different rates.
This phenomena will look very similar to frost wedging and salt crystal growth, but will typically happen in climates that undergo extreme diurnal temperature changes.

34. Mechanical Weathering - Exfoliation
Mechanical Exfoliation - rock breaks apart in layers that are parallel to the earth's surface; as rock is uncovered, it expands (due to the lower confining pressure) resulting in exfoliation.
In this photo from Yosemite National Park, the exfoliation sheets are sub-parallel to the valley walls.