Slide 1 / 157 Slide 2 / 157 New Jersey Center for Teaching and Learning Progressive Science Initiative This material is made freely available at www.njctl.org and is intended for the non-commercial use of Mole / Stoichiometry students and teachers. These materials may not be used for any commercial purpose without the written permission of the owners. NJCTL maintains its Calculations website for the convenience of teachers who wish to make their work available to other teachers, participate in a virtual professional learning community, and/or provide access to course materials to parents, students and others. Click to go to website: www.njctl.org www.njctl.org Slide 3 / 157 Slide 4 / 157 Table of Contents Avogadro's Number Click on the topic to go to that section · Avagadro's Number · Molar Mass · Molar Volume · Percent Composition · Emperical Formula Return to Table of Contents Slide 5 / 157 Slide 6 / 157 Moles Moles Recall an atom's atomic mass is equal to the number of protons plus the number of neutrons in the atom. What if you wanted to measure the mass of one atom in the laboratory? Would it be possible? Atomic Number 6 or number of protons (Z) C 12.01 Atomic Mass in amu The unit for atomic mass is amu. A single atom has a very small mass. Carbon-12 has 6 protons and 6 neutrons. One carbon atom has a mass of about 2.0 x 10 -23 grams . One amu is equal to 1/12 the mass of carbon-12 or approximately the mass of one proton or neutron mass of 1 proton = 1 amu
Slide 7 / 157 Slide 8 / 157 The Mole Calculating Avogadro's Number The atomic mass of one carbon atom is 12.01 amu or 2x10 -23 g. It takes a lot of atoms to give us enough material to directly measure in a lab. How many carbon atoms would it take to get 12.01 grams of carbon? Hydrogen has a mass of 1 amu. How many atoms of hydrogen would be needed to make a 1 gram sample of hydrogen? Givens: mass of 1 carbon atom = 2x10 -23 g 602,200,000,000,000,000,000,000 total mass of carbon atoms = 12.01 g The amount 6.02x10 23 is called Avogadro's number or a mole . 2x10 -23 g x ? of atoms = 12.01 g ? of atoms 12.01 g = How big is a mole? 2x10 -23 g ? of atoms = 6.02 x 10 23 atoms Slide 9 / 157 Slide 10 / 157 Holy Mole-y! The Mole 1 mole of pennies could One mole of marbles would cover the A mole is just a grouping of numbers...like dozen, ream, etc. entire Earth (oceans included) for a be distributed to all the depth of two miles! currently-living people of A dozen means 12 of something. the world so that they A mole means 6.02 x 10 23 of something. could spend a million dollars per hour every hour (day and night) for Common Grouping Quantities the rest of their lives! 1 dozen = 12 1 gross =144 If you were able to count at the rate of 1 million numbers a second, it 1 ream = 500 would take about 20 billion years to count out one mole! 1 mole = 6.02 x 10 23 Slide 11 / 157 Slide 12 / 157 2 How many eggs are in half a dozen eggs? 1 How many eggs are in two dozen eggs? 12 A A 12 24 B 24 B C 0.0833 C 6 D 2 D 0.5 6.02 x 10 23 E 6.02 x 10 23 E
Slide 13 / 157 Slide 14 / 157 4 How many pieces of gold dust are in 2 moles of 3 How many particles of sand are in 0.5 moles of gold dust? sand? A 1.5 x 10 23 A 1.5 x 10 23 B 3.01 x 10 23 B 3.01 x 10 23 C 6.02 x 10 23 C 6.02 x 10 23 D 1.2 x 10 24 D 1.2 x 10 24 E 6.02 x 10 24 E 6.02 x 10 24 1 mole = 6.02 x 10 23 1 mole = 6.02 x 10 23 Slide 15 / 157 Slide 16 / 157 6 How many dozen eggs are in a container of 18 5 How many dozen eggs are in a container of 6 eggs? eggs? 1.5 A A 4 B 3 B 0.5 C 0.67 C 1 D 2 D 2 6.02 x 10 23 E 6.02 x 10 23 E Slide 17 / 157 Slide 18 / 157 8 Mathematicians estimate Earth's beaches 7 The Milky Way Galaxy may have up to 400 billion contain nearly 5.6 x 10 21 grains of sand. How (4 x 10 14 stars). How many moles of stars does it many moles of sand are on Earth's beaches? have? 1.5 x 10 9 A A 1.5 B 6.7 x 10 B 9.3 x 10 -10 -3 C 10 C 10 D 107.5 D 0.5 6.02 x 10 23 E 6.02 x 10 23 E 1 mole = 6.02 x 10 23 1 mole = 6.02 x 10 23
Slide 19 / 157 Slide 20 / 157 Measuring Matter with Moles Measuring Matter with Moles The mole is the SI unit for measuring One mole (mol) of a substance is 6.02 x 10 23 representative the amount of particles in a chemical substance. particles of that substance. N Where: n = N A n is the number of moles N is the total number of particles 1 mole of Carbon N A is Avogadro's Number 6.02 x 10 23 Slide 21 / 157 Slide 22 / 157 9 How many atoms of titanium are in a sample Measuring Matter with Moles containing 0.5 mole of titanium? A 1.5 x 10 23 N A = 6.02 x10 23 atoms N n = B 3.01 x 10 23 N A How many moles of Gold are there in a sample N A = 6.02 x 10 23 containing 3.01 x 10 23 atoms of Gold? C 6.02 x 10 23 D 1.2 x 10 24 E 6.02 x 10 24 Slide 23 / 157 Slide 24 / 157 10 How many atoms of sodium are in a sample 11 How many moles of potassium are in a sample containing 2.0 moles of sodium? containing 3.01 x 10 23 atoms of potassium? A 1.0 N n = 1.5 x 10 23 A N A B 2.0 N n = B 3.01 x 10 23 N A N A = 6.02 x 10 23 C 0.5 N A = 6.02 x 10 23 C 6.02 x 10 23 D 0.75 D 1.2 x 10 24 6.02 x 10 24 E 6.02 x 10 22 E
Slide 25 / 157 Slide 26 / 157 13 How many moles of tungsten atoms are there in a 12 How many moles of potassium are in a sample sample containing 1.8 x 10 24 atoms of tungsten? containing 1.2 x 10 24 atoms of potassium? A 0.33 mol 0.25 mol A N N B n = 0.50 mol n = 0.50 mol B N A N A C 1.0 mol C 1.0 mol N A = 6.02 x 10 23 N A = 6.02 x 10 23 D 2.0 mol 1.5 mol D E 3.0 mol E 3.0 mol Slide 27 / 157 Slide 28 / 157 14 How many moles of silver are there in a pure 15 How many atoms are there in 5.00 mol of hafnium? sample containing 1.5 x 10 23 atoms of silver? A 6.02 x10 23 atoms A 0.10 mol N B 1.20 x 10 23 atoms n = N A N n = B 0.25 mol C 1.20 x 10 22 atoms N A N A = 6.02 x 10 23 C 0.50 mol D 3.43 x 10 23 atoms N A = 6.02 x 10 23 D 1.0 mol E 3.01 x 10 24 atoms E 1.5 mol Slide 29 / 157 Slide 30 / 157 Measuring Matter with Moles Measuring Matter with Moles laboratory sample size A mole of ANY substance contains Avogadro’s number of molecule of H 2 O representative particles, or 6.02 x 10 23 representative particles. H O Avagadro's number of H 1 mole of C atoms = 6.02 X 10 23 atoms of C molecules 18.0 amu (6.02 x10 23 ) 1 mol H 2 O 1 mole of pick-up trucks = 6.02 x 10 23 pick-up trucks (18.0 g) In 1 mole of carbon there are 6.02 x 10 23 carbon atoms. The term representative particle refers to the species or types of particles in the substance In 1 mole of water there are 6.02 x 10 23 water molecules. For Example: In 1 mole of NaCl there are 6.02 x 10 23 formula units. atoms, molecules, formula units, ions
Slide 31 / 157 Slide 32 / 157 16 Formula units refer to particles of __________ 17 How many molecules are there in 2.10 mol CO 2 ? compounds and molecules refer to particles of A 3.79 x 10 24 __________ compounds. N n = B 3.49 x 10 -24 N A A molecular/covalent, ionic C 1.05 x 10 -23 N A = 6.02 x 10 23 B ionic, molecular/covalent D 2.53 x 10 24 C atoms, molecular E 1.26 x 10 24 D atoms, ionic E ionic, atomic Slide 33 / 157 Slide 34 / 157 18 How many moles of helium atoms are there in a 19 How many moles of NaCl are there in a pure pure sample containing 6.02 x 10 24 atoms of sample containing 6.02 x 10 23 formula units of helium? sodium chloride, NaCl? A 2.0 mol N A N 1.0 mol n = n = N A N A B 4.0 mol B 2.0 mol N A = 6.02 x 10 N A = 6.02 x 10 23 23 C 4.0 mol C 6.0 mol D 6.0 mol D 10.0 mol E 6.02 x 10 23 mol 2.4 x 10 24 mol E Slide 35 / 157 Slide 36 / 157 20 How many formula units of Pb(NO 3 ) 2 are there in Real World Application 0.5 mole of Pb(NO 3 ) 2 ? N n = N A A 0.5 formula units Calcium deficiency can cause osteoporosis N A = 6.02 x 10 23 (weakening of the bones). The minimum B 2.0 formula units amount of calcium in 1 mL of blood should be around 1.3 x 10 18 atoms. C 3.01 x 10 23 formula units A patient has her blood tested and the lab finds there are 3 x 10 -5 moles of calcium in D 1.2 x 10 24 formula units the blood. Is this patient at risk for osteoporosis? E 6.02 x 10 23 formula units (6.02 x 10 23 atoms/mole) x (3 x 10 -5 moles) = 1.8 x 10 23 atoms Ca slide for answer This exceeds the normal range so they are OK!
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