Moles (n) Weight (w) molecule count (N)

Multiply Down to weight and molecule count Moles (n) Weight (w) molecule count (N) Divide up to moles

Trips around the triangle: Nw Given: 100 g/mol =MW Given: chemist’s dozen =1 mol count=6.02*1023 Moles (n) w=n*MW =20* 100 6.02*1023 n= 20 6.02*1023 All roads lead through moles Given molecule count N=20 Weight (w) ? w~3.3*10-21 g

Trips around the triangle: wN Given : chemist’s dozen =1 mol count=6.02*1023 Given: 100 g/mol =MW N=n x 6.02*1023 =200 x 6.02*1023 100 n= w = 200 MW 100 Moles (n) All roads lead through moles Given weight w=200 g Molecule count N ? N=1.2*1024

AN ANECDOTE An `out-of-towner’ visiting NYC for the first time asks Joshua Bell (world’s greatest violinist): “How do you get to the Lincoln Center for the Performing Arts ?” Joshua’s answer (supposedly): “Practice, practice, practice….”

Exercise #3a: mole calculations part 1 • weight per mole (MW): what does a mole of • C6H12O6 weigh ? • (C=12; H=1; O=16) =_______ g/mol 6*12 + 12*1 + 6*16 = 180 g/mol 1.1) mole to mass: how many g C6 H12O6 of are present in 0.00555 mole of C6 H12O6? MULTIPLY DOWN TO WEIGHT 0.00555 mol * 180 g/mol = 1 g

Exercise #3a: mole calculations part 1 (continued) 1.2) mass to mole: how many moles of C6 H12O6 are in 360 g of C6H12O6? DIVIDE UP TO MOLES 360 g/180 g mol-1 = 2 moles 1.3) mole to # molecule: how many molecules of C6 H12O6 are in 0.5 mol of C6H12O6 ? MULTIPLY DOWN TO MOLECULES 0.5 mol *6*1023 molecules/mol = 3*1023 molecules

Exercise #3a: mole calculations part 1 (continued) 1.4) mass to # molecules: how many molecules of C6 H12O6 are in 120 g of C6H12O6 ? 1) Divide up to moles; 2) multiply down to molecules 120 g 180 g/mole * 6*1023 moleculesmole =4*1023 molecules

Exercise 3part 1 (continued) 1.5) # molecules to moles: how many moles in 3*1024 molecules of C6H12O6 ? DIVIDE UP TO MOLES 3*1024 molecules = 5 moles 6*1023molecules/mol

Exercise 3 part 1 (continued) 1.6) # molecules to mass: How many grams of C6 H12O6 are in 2.0 *1022 molecules of C6 H12O6 ? DIVIDE UP TO MOLES MULTIPLY DOWN TO WEIGHT 2*1022 molecules 6*1023 molecules/mol * 180 g mol = 6 g

The gram molecular mass of D form N-methylphenyl-2-propan-2-amine (the active form of ‘crystal meth’) is149.2 g/mol. How many moles of crystal meth are in a typical street `teenth’ = 1/16 of an ounce= 1.80 grams ? (Note: 1 mol count=6.022*1023.) • 7.27*1021 • 0.0121 • 82.9 • 2.48*10-22 • 8.98*1025 • 268.5 • My answer isn’t above

B1-Aflatoxin (MW=328.2 g/mol) is a naturally occurring, horribly toxic poison derived from Aspergillus fungi, a common contaminant in corn. It causes cancer in most humans at the staggeringly low exposure level of 1*1017 molecules. What is the equivalent mass of aflatoxin represented by this count ?(Note: 1 mol count=6.022*1023.) • 3.28*10-15 g • 1.84*10-4 g • 5.45*10-5 g • 5.06*10-10 g • 1.98*10-10 g • 6.02*106 g • My answer isn’t above

Micro chip manufacture requires nearly oxygen-free conditions wherein the concentration of O2is at or below 17 pg/L. Given that the atomic mass of O is16g/mol, about how many molecules of O2 /L does this represent ? Note: 1 mol count=6.022*1023 • 5.4*1024 • 3.5*1022 • 5.3*1022 • 3.2*1011 • 6.4*1012 • 1.9*1013 • My answer isn’t above

Moles (n) Weight (w) molecule count (N)