What is a mole? A unit of measurement Since the numbers in chemistry are so small, we use a “preferred unit of measurement” (mole) to represent the small number
What are the units of measurement? "that equal number" of atoms randomly chosen. the number of atoms in the atomic weight in g of any element. the number of atoms in 16 g of oxygen, in 4 grams of He, in 32 g of sulfur, etc. the number of molecules in the molecular weight, in grams, of any compound. the number of molecules in 18 g of water, in 40 g of lithium carbide. Much later, a mole, that equal number, was found to be 6.022 x 10 23 (representative particles).
Examples 1 mole (or abbr. mol) = 12.011 g of Carbon 1 mol of Carbon = 6.02 x 10 23 atoms of C 1 mol of H 2 O = 6.02 x 10 23 molecules of water 1 mol of NaCl = 6.02 x 10 23 units of NaCl
Moles in mass 1 mole can equal the atomic weight of an element. 1mol of C = 12.011g of C 1 mole can equal the atomic weight of a compound 1mol of CO = 12.011g of C + 15.99 g of O = 28.0 g of CO
Practice Problems How many grams of Cu are in 1.20 mol of Cu? How many moles are in 70g of Cl?
Moles in compounds Let’s say you have water aka. H 2 O How many moles of Hydrogen atoms(ions) are in water? Ask yourself how many individual atoms of Hydrogen do you see in water? Did you say 2??? Is that your final answer? You are correct! So how many mols of Oxygen atoms do you see?
Moles in an equation 2 H 2 + O 2 2H 2 O How many moles of Hydrogen molecules are in the reactants? *Coefficients serve as the number of moles too! Therefore, there are 4 mols of Hydrogen gas NOPE!!!! Fooled you.. 2 mols of Hydrogen gas
Molecules Atoms Units Mole Conversion Boomerang
Mole Conversions Mass to mole or vice versa: How many moles are in 24 g of Carbon? Look at the boomerang: Start with the given: 24 g (mass) of C What do you want in the end? Moles of C Use the conversion factor given: 1 mole Atomic mass 24 g of C x 1 mol of C = 2.0 mol of Carbon 12.011 g of C
White Boards Given 200 g of water, how many mols of water do you have? How many grams of carbon monoxide are in 1.5 mols of carbon monoxide?
More conversion Mole to atoms/molecules/particles or vice versa How many atoms are in 2.00 mols of Carbon? Look at the boomerang: Where do you begin? (the given: mols) What do you need in the end? (atoms: particles) What’s the conversion factor? 6.02 x 10 23 Atoms of C 1 Mols of C 2.00 mols of C x 6.02 x 10 23 atoms of C = 1.20 x 10 24 atoms C 1 mol of C
White boards How many molecules of oxygen gas are in 3.0 mols of Oxygen gas? How many mols of Oxygen gas are in 4.67 x 10 24 molecules of Oxygen gas?
More conversion Mole to volume of gas or vice versa What is the volume occupied by 2 mols of hydrogen gas? Look at the boomerang: Where do you begin? (the given: mols) What do you need in the end? (volume of gas) What’s the conversion factor? 22.4 L of H 2 1 Mols of H 2 2.00 mols of H 2 x 22.4 L of H 2 = 44.8 L of H 2 1 mol of H 2
White boards Convert 4.38 moles of He to liters Convert 3.01 L of N to moles
Practice Must show work (dimensional analysis) How many grams are in 1 mol of Mercury? Given a 1.5 mols of carbon dioxide, how many molecules of carbon dioxide do you have?