1. Chemistry 3/11/15 Formula Mass and Molar Mass

2. Drill Make sure you have a calculator!! What is the atomic mass of sodium? What about sodium chloride? Magnesium chloride? HW: Moles and Mass WS (front ONLY) March Mole Madness Chem Joke of the Day What do you call a clown in jail? A silicon

3. Objectives IWBAT Calculate formula or molar mass. Convert from moles to grams, and back again.

4. Formula Mass What is formula mass? The formula mass of any molecule, formula unit, or ion is the sum of the average atomic masses of the atoms represented in the formula. What is a molecule? Formula unit? Ion?

5. Calculating Formula Mass Remember atomic mass? Atomic mass of Na = ? 22.99 u This is from the periodic table Now, we learn formula mass: What is the formula mass of NaCl? 22.99 u Na + 35.45 u Cl (mass of Cl) So, it is 58.44 u NaCl

6. What about other formulas? What’s the formula mass of nitrogen tribromide? First, what’s the formula? NBr 3 Then, what should we do with the 3 bromines? 1(14.01 u)= 14.01 u 3(79.90 u) = 239.70 u Total = 14.01 u + 239.70 u = 253.71 u NBr 3

7. Let’s practice formula mass! 1. Na 2 SO 3 2. H 2 SO 4 3. MnO 4 - 4. C 2 H 6 O 5. Ca(NO 3 ) 2 2H 2 O Make sure to show all your work! 1. 126.05 u 2. 98.09 u 3. 118.94 u 4. 46.08 u 5. 200.14 u

8. What is a mole? A mole is a counting unit, that allows chemists to use the Periodic Table in another way. What is the formula mass of Na? 22.99 u What is the mass of one mole of Na? 22.99 g  Wow!

9. How much is the molar mass? How big is a mole? Take out a sheet of notebook paper. You will go to the lab area—there are graduated cylinders that each contain ONE MOLE of a substance. Write down the formula for the substance, and calculate the mass of that ONE MOLE. Let’s discuss!

10. Molar Mass Formula mass is the mass of…??? Molar mass is the mass, in grams, of one mole of a substance. Molar mass and formula mass are numerically equivalent, but molar mass is measured in grams per 1 mole (g/mol).

11. Calculate the number of moles in 58.4 grams of Carbon. 12.01 g C = 1 mol C 58.4 g C = ? mol C 58.4 g C x 1 mol C = 4.86 mol C 12.01 g C

12. Calculate the number of grams in 3.80 mol of copper (II) carbonate What’s the formula for copper (II) carbonate? CuCO 3 What’s the molar mass of CuCO 3 ? 63.54 g + 12.01 g + 3(16.00 g) 123.55 g/mol 3.80 mol CuCO 3 = ?? g CuCO 3 3.80 mol CuCO 3 x 123.55 g CuCO 3 = 469 g CuCO 3 1 mol CuCO 3

13. Let’s Practice! Start Moles and Mass WS

14. Closure How confident do you feel about…? calculating Formula mass Molar mass converting grams  moles moles  grams