Avogadro's Number Click on the topic to go to that section - PDF document

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 11 (Answer) / 157 1 How many eggs are in two dozen eggs? 1 How many eggs are in two dozen eggs? A 12 A 12 24 24 B B C 0.0833 C 0.0833 D 2 D 2 6.02 x 10 23 6.02 x 10 23 E E Answer B [This object is a pull tab]

Slide 12 / 157 Slide 12 (Answer) / 157 2 How many eggs are in half a dozen eggs? 2 How many eggs are in half a dozen eggs? 12 12 A A 24 24 B B C 6 C 6 D 0.5 D Answer 0.5 C 6.02 x 10 23 6.02 x 10 23 E E [This object is a pull tab] Slide 13 / 157 Slide 13 (Answer) / 157 3 How many particles of sand are in 0.5 moles of 3 How many particles of sand are in 0.5 moles of sand? sand? 1.5 x 10 23 1.5 x 10 23 A A B 3.01 x 10 23 B 3.01 x 10 23 C 6.02 x 10 23 C 6.02 x 10 23 Answer D D 1.2 x 10 24 1.2 x 10 24 B 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 [This object is a pull tab] Slide 14 / 157 Slide 14 (Answer) / 157 4 How many pieces of gold dust are in 2 moles of 4 How many pieces of gold dust are in 2 moles of gold dust? gold dust? 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 Answer E 6.02 x 10 24 E 6.02 x 10 24 D 1 mole = 6.02 x 10 23 1 mole = 6.02 x 10 23 [This object is a pull tab]

Slide 15 / 157 Slide 15 (Answer) / 157 5 How many dozen eggs are in a container of 6 eggs? 5 How many dozen eggs are in a container of 6 eggs? A A 4 4 B 0.5 B 0.5 C 1 C 1 Answer D D 2 2 C 6.02 x 10 23 6.02 x 10 23 E E [This object is a pull tab] Slide 16 / 157 Slide 16 (Answer) / 157 6 How many dozen eggs are in a container of 18 6 How many dozen eggs are in a container of 18 eggs? eggs? 1.5 1.5 A A B 3 B 3 C 0.67 C 0.67 Answer D D 2 2 A 6.02 x 10 23 6.02 x 10 23 E E [This object is a pull tab] Slide 17 / 157 Slide 17 (Answer) / 157 7 The Milky Way Galaxy may have up to 400 billion 7 The Milky Way Galaxy may have up to 400 billion (4 x 10 14 stars). How many moles of stars does it (4 x 10 14 stars). How many moles of stars does it have? have? 1.5 x 10 9 1.5 x 10 9 A A B 6.7 x 10 B 6.7 x 10 -10 -10 C 10 C 10 Answer A D D 0.5 0.5 6.02 x 10 23 6.02 x 10 23 E E 1 mole = 6.02 x 10 23 1 mole = 6.02 x 10 23 [This object is a pull tab]

Slide 18 / 157 Slide 18 (Answer) / 157 8 Mathematicians estimate Earth's beaches 8 Mathematicians estimate Earth's beaches contain nearly 5.6 x 10 21 grains of sand. How contain nearly 5.6 x 10 21 grains of sand. How many moles of sand are on Earth's beaches? many moles of sand are on Earth's beaches? 1.5 1.5 A A B 9.3 x 10 B 9.3 x 10 -3 -3 Answer C 10 C 10 D D 107.5 D 107.5 6.02 x 10 23 6.02 x 10 23 E E 1 mole = 6.02 x 10 23 1 mole = 6.02 x 10 23 [This object is a pull tab] 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 n = Where: 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? 1.5 x 10 23 A 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 22 (Answer) / 157 Slide 23 / 157 9 How many atoms of titanium are in a sample 10 How many atoms of sodium are in a sample containing 0.5 mole of titanium? containing 2.0 moles of sodium? 1.5 x 10 23 A A 1.5 x 10 23 N n = N B 3.01 x 10 23 N A n = B 3.01 x 10 23 N A N A = 6.02 x 10 23 C 6.02 x 10 23 N A = 6.02 x 10 23 Answer C 6.02 x 10 23 D 1.2 x 10 24 B D 1.2 x 10 24 E 6.02 x 10 24 6.02 x 10 22 E [This object is a pull tab] Slide 23 (Answer) / 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 3.01 x 10 23 atoms of potassium? containing 2.0 moles of sodium? 1.0 A N n = A 1.5 x 10 23 N A 2.0 B N n = B 3.01 x 10 23 N A N A = 6.02 x 10 C 0.5 23 N A = 6.02 x 10 23 C Answer 6.02 x 10 23 0.75 D D D 1.2 x 10 24 6.02 x 10 24 E 6.02 x 10 22 E [This object is a pull tab] Slide 24 (Answer) / 157 Slide 25 / 157 11 How many moles of potassium are in a sample 12 How many moles of potassium are in a sample containing 3.01 x 10 23 atoms of potassium? containing 1.2 x 10 24 atoms of potassium? A 1.0 A 0.25 mol N n = N A N B 2.0 B 0.50 mol n = N A C 1.0 mol N A = 6.02 x 10 23 C 0.5 N A = 6.02 x 10 23 D 2.0 mol D Answer 0.75 E 3.0 mol C 6.02 x 10 24 E [This object is a pull tab]

Slide 25 (Answer) / 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 Answer 1.5 mol D E 3.0 mol D E 3.0 mol [This object is a pull tab] Slide 26 (Answer) / 157 Slide 27 / 157 14 How many moles of silver are there in a pure 13 How many moles of tungsten atoms are there in a sample containing 1.5 x 10 23 atoms of silver? sample containing 1.8 x 10 24 atoms of tungsten? A 0.33 mol A 0.10 mol N N n = B 0.50 mol n = B 0.25 mol N A N A C 0.50 mol C 1.0 mol N A = 6.02 x 10 23 N A = 6.02 x 10 23 D 1.0 mol Answer D 1.5 mol E E 1.5 mol E 3.0 mol [This object is a pull tab] Slide 27 (Answer) / 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 1.20 x 10 23 atoms B n = N A N n = 0.25 mol B 1.20 x 10 22 atoms N A C 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 Answer E 3.01 x 10 24 atoms B E 1.5 mol [This object is a pull tab]