THE MOLE You should be able to: Convert between molecular weight, number of atoms, number of moles, or mass Determine % composition of an atom

What is a mole A mole is a counting unit like: 12 eggs = a dozen eggs 60 sec = a min 500 sheets of paper = ream

What is a mole 1 mole of Cu, Al, S, K2Cr2O7, H2O and CuCl2 Moles count particles 6.022 x 1023 particles = a mole (mol) Called avagadro’s number (# atoms in 12 g 12C) 1 mol marbles would cover earth 50 mi deep! 1 mole of Cu, Al, S, K2Cr2O7, H2O and CuCl2

What is a mole Uses To count number of particles in a sample (from mass) Since 12 g 12C = 6.022 x 1023 atoms 12.01 g sample of natural carbon = 6.022 x 1023 atoms (12C, 13C, and 14C) Help use in determining outcome of reactions

practice How many atoms of Ar = 7.5 mol ? D.A. ?: 7.5 mol = ? Atoms Ar

practice How many mols are in 10.0 g of Al? D.A. ?: 10g Al= ? Mols Al How many atoms? D.A. ?: 0.371 moles = ? Atoms

Molar mass A chemical compound = collection of atoms Ex CO2 Calculate the mass of 1 mol of CO2 Think about it: mass of 1 mol of CO2 = mass of 1 mol C + 2 mols of O Mass of 1 mol of C = 12.01g and Mass of 2 mols of O= 2 x 16.00 g Mass of 1 mol of CO2 = 12.01 g + 2 (16.00 g) =44.01 g = MOLAR MASS of CO2 (mass of 1 mole of CO2)

Molar Mass Calculate the molar mass of CH4 = 12.01g + 4(1.008 g) = 16.04 g Calculate how many moles are in 1.56 x 10-2 g of C10H6O3 Think about it First need molar mass then do DA to solve =8.96 x 10-5 mol C10H6O3

% composition Tells us % mass of an individual atom in a molecule % comp.= mass of element in 1 mol of molecule x 100% mass of 1 mol of molecule % comp. of H in H2O Mass of H= 2 mol (1.008 g) = 2.016 g Mass of 0= 1 mol (16.00 g) = 16.00 g Mass of 1 mol H2O = 2.016 g + 16.00 g = 18.016 g % composition of H=mass of H in 1 mol of H2O x 100 % mass of 1 mol of H2O = 2.016g x 100 % = 11.2 % 18.016g