convert the following: m = ______dm 2.5days =________minutes dm 3 = _______ m x 10 6 – 2 x 10 5 = _____ 5.Find the gfw of NaCl 6.ACT-prep question: 1.Many physicists believe the elementary particles of the atom are composed of still more elementary particles called the: a)photons b)quarks c)neutrons d)electrons Quiz: Factor Label Method 0.30 m (10 dm) (1 m) 3 5 days (24hours) (60 min) (1 day)(1 hour) 7.2 x dm 3 (1 3 m 3 ) (10 3 dm 3 ) 4 February 24, x 10 6 – 0.2 x 10 6 Na = 23 amu, Cl = 35 amu 1(23) + 1(35) = 58 amu or 58 g/mole 1.0 x 10 6

Gram Formula Weight of HCl amu amu = amu or g/mole

Gram Formula Weight of NH amu amu (1.008) = amu or g/mole N H H H

Gram Formula Weight of (NH 4 ) 2 O O 2- N = 14 amu H = 1 amu O = 16 amu 2N = 2(14 amu) 2x4H = 8(1 amu) 1O = 1(16 amu) 28 amu 8 amu 16 amu 52 amu or 52 g/mole

Quiz: Find the gfw for the following compounds… 1.CaCl 2.Al 2 S 3 3.Ca 3 (PO 4 ) = 75 g/mole 2.2(27) + 3(32) = = 150 g/mole 3.3(40) + 2(31) + 8(16) = = 310 g/mole

Using the GFW (gram formula weight) for calculations The gram formula weight (gfw) is a conversion factor, just like 100 cm = 1 m or 1 Avogadro number of particles = 1 mole. Use the same procedure as before: Write the known, then write the appropriate conversion factor. Underline the important facts.: Example: How many moles of NaCl are in 4.00 grams of NaCl? Na = 23.0 amu Cl = 35.5 amu 58.5 g/mole 4.00 g NaCl 58.5 g NaCl 1 mole NaCl mole NaCl

Find the number of moles in grams of the following: CaCO 3 Ca 3 (PO 4 ) 2 Ca = 40 C = 12 3O = 3(16) = g/mole Known: grams CaCO g/mole Find: moles CaCO 3 (0.020 grams CaCO 3 )(1mole CaCO 3 ) ( 100 g CaCO 3 ) = 2.0 x moles CaCO 3 3Ca = 3(40) = 120 2P = 2(32) = 64 8O = 8(16) = g/mole Known: moles Ca 3 (PO 4 ) g/mole Find: grams Ca 3 (PO 4 ) 2 (0.020 grams Ca 3 (PO 4 ) 2 )(mole Ca 3 (PO 4 ) 2 ) ( 312 g Ca 3 (PO 4 ) 2 ) = 6.4 x moles Ca 3 (PO 4 ) 2 or moles Ca 3 (PO 4 ) 2

Another example of using the GFW for calculations Use the same procedure as before: Write and underline the known, then write the appropriate conversion factor: Example: How many grams of NaCl are in 0.2 moles of NaCl? Na = 23.0 amu Cl = 35.5 amu 58.5 g/mole 0.2 mole NaCl 58.5 g NaCl 1 mole NaCl 11.7 g NaCl

Find the number of grams in moles of the following: CaCO 3 Ca 3 (PO 4 ) 2 Ca = 40 C = 12 3O = 3(16) = g/mole Known: moles CaCO g/mole Find: grams CaCO 3 (0.020 moles CaCO 3 )(100g CaCO 3 ) ( mole CaCO 3 ) = 2.0 g CaCO 3 3Ca = 3(40) = 120 2P = 2(32) = 64 8O = 8(16) = g/mole Known: moles Ca 3 (PO 4 ) g/mole Find: grams Ca 3 (PO 4 ) 2 (0.020 moles Ca 3 (PO 4 ) 2 )(312g Ca 3 (PO 4 ) 2 ) ( mole Ca 3 (PO 4 ) 2 ) = 6.24 g Ca 3 (PO 4 ) 2 Rounded to 6.2 g Ca 3 (PO 4 ) 2