1. Chemical Formulas The Mole One-Step Molar Conversions February 24, 2014

2. Calculator Periodic Table A good attitude about math Materials

3. Covalent:C 8 H 18 – Octane – # Carbon: 8 – # Hydrogen: 18 Ionic:Al 2 (SO 4 ) 3 – Aluminum Sulfate – # Aluminum: 2 – # Sulfur: 3 – # Oxygen: 12 (4 O’s in each sulfate, 3 sulfates in the compound, 3 x 4 = 12) Chemical Formulas

4. The mass of one molecule, formula unit, or ion. Calculate by adding atomic masses together from the periodic table. Units: amu (atomic mass unit) Formula Mass

5. Mass H + Mass Cl 1.0079 + 35.453 = 36.4069 amu Example: HCl

6. Mass N + 4(Mass H) + Mass N + 3(Mass O) 14.007 + 4(1.0079) + 14.007 + 3(15.999) = 80.0426 amu OR 2(Mass N) + 4(Mass H) + 3(Mass O) 2(14.007) + 4(1.0079) + 3(15.999) = 80.0426 amu Example: NH 4 NO 3

7. Mass P + 4(Mass O) 30.974 + 4(15.999) = 94.97 amu The charge does not affect the mass because the mass of an electron is so very small that it is negligible (able to be ignored). Example: PO 4 3-

8. And now: MOLES

9. The Mole 1 mole = 6.02 × 10 23 particles It is the number of atoms in exactly 12.0 g of carbon-12 It is used the same way as: – A dozen (12) – A pair (2) – A score (20) Avogadro’s number

10. How did they come up with 6.02 x 10 23 anyway? If you divide the charge on a mole of electrons by the charge on a single electron you obtain a value of Avogadro’s number of 6.02214154 x 10 23 particles per mole.

11. Covalent:C 8 H 18 – Octane – Moles Octane: 1 – Moles Carbon: 8 – Moles Hydrogen: 18 Ionic:Al 2 (SO 4 ) 3 – Aluminum Sulfate – Moles aluminum sulfate: 1 – Moles Aluminum: 2 – Moles Sulfur: 3 – Moles Oxygen: 12 Chemical Formulas

12. Mass of one mole (6.022 × 10 23 ) of any molecule, formula unit, or ion. Calculate by adding atomic masses together from the periodic table. Units: g/mol Molar Mass

13. 2(Mass H) + Mass S + 4(Mass O) 2(1.0079) + 32.066 + 4(15.999) 98.0178 g/mol Example: H 2 SO 4

14. Mass Ca + 2(Mass N) + 6(Mass O) 40.078 + 2(14.007) + 6(15.999) = 164.086 g/mol OR Mass Ca + 2((Mass N) + 3(Mass O)) 40.078 + 2((14.007) + 3(15.999)) = 164.086 g/mol Example: Ca(NO 3 ) 2

15. Molar Conversions Mass in grams Amount in moles Divide by the molar mass Multiply by the molar mass

16. Start with: g End with: moles Math: divide by molar mass Molar mass of calcium chloride, CaCl 2 40.078 + 2(35.453) = 110.984 g/mol 2.0 g CaCl 2 = 0.018 mol 110.984 g/mol Example: How many moles are in 2.0 g calcium chloride?

17. Start with: moles End with: g Math: multiply by molar mass Molar mass of potassium iodide, KI 39.098 + 126.90 = 165.998 g/mol 1.5 mol x 165.998 g/mol = 248.997 g Example: How many grams are in 1.5 mol potassium iodide?

18. Amount in moles Number of particles Formula unit Molecule Ion Atom Multiply by Avogadro’s # Divide by Avogadro’s # Molar Conversions

19. Start with: mol End with: formula units (particles) Math: multiply by Avogadro’s number 6.0 mol x 6.02 x 10 23 =3.612 x 10 24 f. units Calculator Help: Use the EE button EE = x 10 6.02 x 10 23 = 6.02EE23 Example: How many formula units are in 6.0 mol calcium bromide?

20. Start with: molecules (particles) End with: moles Math: divide by Avogadro’s number 5.0 x 10 22 molecules = 0.083 mol 6.02 x 10 23 molecules/mol Calculator Help: Use the EE button 6.02 x 10 23 = 6.02EE23 Example: How many moles are in 5.0 × 10 22 molecules H 2 ?