1. Simplified for May 2013 – Stoi–chi–o–met–try – – Stoi–chi–o–met–try – (Rhymes with “toy-key-ah-met-tree”) (Rhymes with “toy-key-ah-met-tree”) Stoichiometry– The Mole Concept Applied To Balanced Chemical Equations! Stoichiometry– The Mole Concept Applied To Balanced Chemical Equations!

2. 1. In a factor label problem, two substances from the balanced chemical equation are picked to work with. One of the substances will be used as the “given” in your word problem, and the other substance will show up as the “want to know” in your word problem. 1. In a factor label problem, two substances from the balanced chemical equation are picked to work with. One of the substances will be used as the “given” in your word problem, and the other substance will show up as the “want to know” in your word problem.

3. 2. Since the coefficients of the chemical equation have the unit, “mole”, the coefficients establish the proportions (ratios) in moles, that exist between the substances reacting in, and being produced during, a chemical reaction. 2. Since the coefficients of the chemical equation have the unit, “mole”, the coefficients establish the proportions (ratios) in moles, that exist between the substances reacting in, and being produced during, a chemical reaction.

4. 3. Until now you were focused on one particular substance, and/or the atoms within its formula, for each word problem; but, now you must work with 2 substances for each word problem. The coefficients will be used as one of your factors (fractions), and it will be called the “mole ratio” factor. 3. Until now you were focused on one particular substance, and/or the atoms within its formula, for each word problem; but, now you must work with 2 substances for each word problem. The coefficients will be used as one of your factors (fractions), and it will be called the “mole ratio” factor. The mole ratio factor is the only way that you may convert (or move) between the one “given” substance, and the other “want to know” substance. The mole ratio factor is the only way that you may convert (or move) between the one “given” substance, and the other “want to know” substance.

5. 4. All of the other parts of the “mole road map” still apply to the substances in the chemical equation, and are used within a stoichiometry problem to convert between molar mass, molar volume, and Avogadro’s number for any of the substances in the chemical equation. 4. All of the other parts of the “mole road map” still apply to the substances in the chemical equation, and are used within a stoichiometry problem to convert between molar mass, molar volume, and Avogadro’s number for any of the substances in the chemical equation.

6. Guided Practice: Guided Practice: Given chemical equation: 2 Na + Cl 2 ––> 2 NaCl What is the mole ratio between Na and Cl 2 ? Answer: 2 moles Na = 1 mole Cl 2

7. 6. What would be the conversion factor necessary in order to convert from moles of Na to moles of Cl 2 ? 2 Na + Cl 2 ––> 2 NaCl

8. 2 Na + Cl 2 ––> 2 NaCl Given that 34 moles Na reacted, calculate how many moles Cl2 also reacted.

9. 8. Your Turn: Using the above chemical equation, if 79.21 moles of NaCl are produced, how many moles of Na reacted during? 8. Your Turn: Using the above chemical equation, if 79.21 moles of NaCl are produced, how many moles of Na reacted during? 2 Na + Cl 2 ––> 2 NaCl

10. 8. Your Turn: 8. Your Turn: given: 79.21 moles of NaCl Want to know: moles of Na

11. Putting It together: Using the above chemical equation, if 79.21 moles of NaCl are produced, what is the mass of Na that reacted during the reaction? Putting It together: Using the above chemical equation, if 79.21 moles of NaCl are produced, what is the mass of Na that reacted during the reaction? You will need to use 2 factors! You will need to use 2 factors! 2 Na + Cl 2 ––> 2 NaCl

12. Putting It together: Putting It together: Given 79.21 moles of NaCl Given 79.21 moles of NaCl Want to know mass of Na Want to know mass of Na You will need to use 2 factors! You will need to use 2 factors! 2 Na + Cl 2 ––> 2 NaCl Mole ratio (coefficients) Molar mass.

13. 10. Using the above equation, if 79.21 moles NaCl are produced, what is the volume of diatomic chlorine gas (Cl 2 ) that reacted? 10. Using the above equation, if 79.21 moles NaCl are produced, what is the volume of diatomic chlorine gas (Cl 2 ) that reacted? 2 Na + Cl 2 ––> 2 NaCl

14. 10. Given: 79.21 moles NaCl 10. Given: 79.21 moles NaCl Want to know volume of diatomic chlorine gas (Cl 2 ) Want to know volume of diatomic chlorine gas (Cl 2 ) 2 Na + Cl 2 ––> 2 NaCl

15. 11. Using the above equation, if 8.32 x 10 25 atoms of Cl are produced, how many moles of Na reacted during the reaction? You will need 3 factors! 2 Na + Cl 2 ––> 2 NaCl

16. Given: 8.32 x 10 25 atoms of Cl Want to know: moles of Na 2 Na + Cl 2 ––> 2 NaCl Mole ratio (coefficients) Avogadro’s number Formula Change