2. Chemical Reactions

3. BELLWORK BRIEFLY WRITE ABOUT A SCIENTIFIC OBSERVATION YOU MADE RECENTLY

4. Chemical equations WE USE CHEMICAL EQUATIONS TO DESCRIBE CHEMICAL REACTIONS

5. Burning Coal

6. This is a chemical reaction The purpose of the equation is to show what was present before the reaction (carbon and oxygen) and afterwards (carbon dioxide)

7. The substances that undergo change are reactants (carbon and oxygen) New substances formed as a result of that change are called products REACTANTS PRODUCTS

8. CARBON + OXYGEN CARBON DIOXIDE SIMPLIFY: C+O 2 CO 2

9. CHEMICAL EQUATION A CHEMICAL EQUATION IS A REPRESENTATION OF A CHEMICAL REACTION IN WHICH THE REACTANTS AND PRODUCTS ARE EXPRESSED AS FORMULAS.

10. CONSERVATION OF MASS THE LAW OF THE CONSERVATION OF MASS: MASS IS NEITHER CREATED NOR DESTROYED IN A CHEMICAL REACTION ALTHOUGH THE MASS OF THE COAL WAS REDUCED DURING THE REACTION, IT WAS NOT LOST THE MASS OF THE CARBON DIOXIDE CREATED WAS EQUAL TO THE MASS OF THE COAL THAT WAS LOST

11. BALANCING EQUATIONS ACCORDING TO THE LAW OF CONSERVATION OF MASS, EACH SIDE OF AN EQUATION MUST BE EQUAL H 2 + O 2 H 2 O WHAT IS WRONG WITH THIS EQUATION?

12. TO BALANCE WE SIMPLY ADD COEFFICIENTS: – THE NUMBERS THAT APPEAR BEFORE THE EQUATION H 2 + O 2 H 2 O= H 2 + O 2 2H 2 O WHAT IS WRONG WITH THIS EQUATION? HOW CAN WE FIX IT?

13. ANSWER 2H 2 + O 2 2H 2 O WHICH MEANS: – TWO MOLECULES OF HYDROGEN REACT WITH ONE MOLECULE OF OXYGEN TO YIELD TWO MOLECULES OF WATER

14. http://PHSchool.com/webcodes10/index.cfm? wcprefix=ccp&wcsuffix=1071&area=view&x=1 3&y=7 http://PHSchool.com/webcodes10/index.cfm? wcprefix=ccp&wcsuffix=1071&area=view&x=1 3&y=7

15. MATH SKILLS READ OVER THE MATH SKILLS EXAMPLES AND STEPS FOR BALANCING EQUATIONS ON PAGE 195 THEN, TRY THE MATH PRACTICE 1-3

16. Balancing equations tutorials http://www.youtube.com/watch?v=RnGu3xO 2h74 http://www.youtube.com/watch?v=RnGu3xO 2h74 http://www.youtube.com/watch?v=gskm- dfKv5g http://www.youtube.com/watch?v=gskm- dfKv5g

17. BELLWORK BALANCE THE FOLLOWING CHEMICAL EQUATION: H 2 +O 2  H 2 O

18. WHAT ARE SOME UNITS OF MEASURE THAT YOU KNOW OF?

20. A. What is the Mole? A counting number (like a dozen) Avogadro ’ s number (N A ) 1 mol = 6.02  10 23 items A large amount!!!!

21. Counting with Moles MOLE: (MOL) AN AMOUNT OF A SUBSTANCE THAT CONTAINS APPROXIMATELY 6.02 X 10 23 PARTICLES OF THAT SUBSTANCE. KNOWN AS AVOGADRO’S NUMBER A MOLE OF A SUBSTANCE GENERALLY CONTAINS 6.02 X 10 23 ATOMS, MOLECULES, OR IONS OF THAT SUBSTANCE

23. n 1 mole of hockey pucks would equal the mass of the moon! A. What is the Mole? 1 mole of pennies would cover the Earth 1/4 mile deep! n 1 mole of basketballs would fill a bag the size of the earth!

25. Molar Mass THE MASS OF DIFFERENT ELEMENTS ARE DIFFERENT, AS IS THEIR MOLAR MASS THE MOLAR MASS OF AN ELEMENT IN THE SAME AS ITS ATOMIC MASS EXPRESSED IN GRAMS

26. MASS OF COMPOUNDS YOU CAN FIND THE MASS OF COMPOUNDS BY ADDING THE MASS OF THEIR COMPONENTS A CARBON DIOXIDE MOLECULE: CARBON= 12 GRAMS OXYGEN = 16 GRAMS X 2 = 32 GRAMS 12 + 32 = 44 GRAMS CARBON DIOXIDE HAS A MOLAR MASS OF 44 GRAMS

27. LETS TRY MOLAR MASS OF C MOLAR MASS OF Fe MOLAR MASS OF H 2 O

28. MOLE-MASS CONVERSIONS TO FIND HOW MANY MOLES ARE IN A CERTAIN # OF GRAMS OF AN ELEMENT OR MOLECULE: Y GRAMS x1/z grams= x moles

30. Example WE HAVE 55 GRAMS OF CO 2 HOW DO WE FIND HOW MANY MOLES WE HAVE? 55 X 1 mol/44 g 1 mol/44 g=.02272727 mol.02272727mol X 55 g = 1.25 mol CO 2

31. BELLWORK WHAT IS A MOLE? WHY DO WE USE MOLES? HOW MUCH IS ONE MOLE OF BARIUM IN GRAMS? CARBON DIOXIDE? WATER?

32. REVIEW: A mole is just a number, nothing else That number is 6.02 x 10 23 We use this number to make otherwise incredibly small numbers (such as the mass of an atom) easy to use in chemical formulas

33. Review There are two conversions we will do with moles: – Find how many moles there are in a certain number of grams (mass) an element or molecule – Find the the number of grams (mass) there are in a certain number of moles of an element or molecule

34. Two conversion factors a)Gramsb)1 Mol 1 Molor Grams How many grams, use conversion factor a How many moles, use conversion factor b

35. Practice Suppose we have 55 grams of CO 2 How do we find how many moles of CO 2 there are in 55 grams of CO 2 ? Step 1: find the molar mass of CO 2 44 grams Step 2: set up the equation 55 grams CO 2 x 1 mol CO 2 = ? mol CO 2 44 grams CO 2

36. Step 3: Solve the equation 55 grams CO 2 x 1 mol CO 2 = ? mol CO 2 44 grams CO 2 1/44=