Chapter 10.1 and 10.2

1. Chapter 10.1 and 10.2 Calculating atoms

2. Molar Mass Is the same as the atomic weight on the periodic table Element Examples 12.01 g C = 1 mol C 1.01 g H = 1 mol H 55.85 g Fe = 1 mol Fe

3. Molar Mass To find the molar mass of a compound Count the number of each element Multiply that number by the Average Atomic mass for that element Add all the elements total masses together

4. Calculate molar mass of magnesium carbonate 84.3 g/mole 24.3 g + 12.0 g + 3 x (16.00 g) = So, 84.3 g/mole = molar mass for magnesium carbonate

5. Examples = 78.05 g/mol = 92.02 g/mol = 12.01 g/mol = 164.10 g/mol • Calculate the molar mass of: Na2S N2O4 C Ca(NO3)2

6. What is the mole? Not this kind of mole!

7. Mole - a word used to represent a large number of objects. Moldy

8. Avogadro’s Number: the number of particles in one mole of particles. 1 mole particles = 602,000,000,000,000,000,000,000 particles 1 mole particles = 6.02 X 1023 representative particles **Memorize this number for the test**

9. The Mole • 12 donuts = 1 dozen donuts • 12 ears of corn = 1 dozen ears of corn • 6.02 X 1023 particles = 1 mole particles. • Molar mass is the mass listed on the periodic table in red rounded to closest whole number • Molar mass = 1 mole atoms = 6.02 X 1023 atoms

10. What are Representative Particles? atom Br2 I2 N2 Cl2 H2 O2 F2 • The smallest pieces of a substance: • molecular compound - molecule • ionic compound - formula unit(made of ions) • element: is the • Remember the 7 diatomic elements? (made of molecules)

11. Solving Problems in Chemistry

12. Required Work for Solving Problems in Chemistry • List given • List conversions • Start with given information including proper units • Determine the units for your answer. • Put in conversions until the last unit is what you are solving for.

13. Solving Problems in Chemistry Given: 3 moles of sulfur atoms = ? Sulfur atoms Conversion: 1 mole of sulfur atoms = 6.02 X 1023 sulfur atoms 1. How many sulfur atoms are equivalent to 3 moles of sulfur atoms? 6.02 x 1023 atoms S 1 mole S 1.806 x 1024 atoms S 3 moles S X = 1.806 x 1024 atoms S 1

14. 6.02 X 1023 atoms Na 1 mole Na X 2. How many atoms are present in 3.7 moles of sodium? List given: 3.7 moles Na = ? atoms Na List conversions: 1 mole Na = 6.02 X 1023 atoms Na Set Up: 3.7 moles Na = 2.22 X 1024 atoms Na 2.22 X 1024 atoms Na 1

15. 6.02 X 1023 atoms As 1 mole As X 3. How many atoms are present in 155 moles of Arsenic? List given: 155 moles As = ? atoms As List conversions: 1 mole As = 6.02 X 1023 atoms As Set Up: 155 moles As 9.33 X 1025 atoms As = 9.33 X 1025 atoms As 1

16. Atoms to Moles

17. 1 mole Xe 6.02 X 1023 atoms Xe X 1. How many moles of Xenon are equivalent to 5.66 X 1026atoms Xe? List given: 5.66 X 1026 atoms Xe = ? moles Xe List conversions: 1 mole Xe = 6.02 X 1023 atoms Xe Set Up: 5.66 X 1026 atoms Xe 5.66 X 1026 moles Xe = 940.2 moles Xe 6.02 X 1023

18. 1 mole Ag 6.02 X 1023 atoms Ag X 2. How many moles of Silver are equivalent to 2 .888 X 1015 atoms Ag? List given: 2.888 X 1015 atoms Ag = ? moles Ag List conversions: 1 mole Ag = 6.02 X 1023 atoms Ag Set Up: 2.888 X 1015 atoms Ag 2.888 X 1015 moles Ag = 4.8 X 10-9 moles Ag 6.02 X 1023

19. Moles To Grams

20. Given: 3 moles S = ? Grams S Conversion: 1 mole S = 32 grams S 1. moles of sulfur atoms equals how many grams of sulfur? 3 moles S 32 grams S 1 mole S 96 grams S X = 96 grams S 1

21. 80 grams Br 1 mole Br X 2. Find the mass in grams of 8.6 moles bromine List given: 8.6 moles Br = ? grams Br List conversions: 1 mole Br = 80 grams Br Set Up: 8.6 moles Br 688grams Br = 688grams Br 1

22. 28 grams Si 1 mole Si X 3. Find the mass in grams of 7.55 moles silicon List given: 7.55 moles Si = ? grams Si List conversions: 1 mole Si = 28 grams Si Set Up: 7.55 moles Si 211.4grams Si = 211.4grams Si 1

23. Grams to Moles

24. 1 mole C 12 grams C X 1. How many moles are in 38 grams of Carbon? List given: 38 grams C = ? moles C List conversions: 1 mole C = 12 grams C Set Up: 38 grams C 38 moles C = 3.17 moles C 12

25. 1 mole H 1 grams H X 2. How many moles are in 2 grams of Hydrogen? List given: 2 grams H = ? moles H List conversions: 1 mole H = 1 grams H Set Up: 2 grams H 2 moles H = 2 moles H 1

26. Grams to Particles

27. Solving Problems in Chemistry Given: 57 grams S = ? atoms S Conversion: 1 mole S = 32 grams S 1 mole S = 6.02 X 1023 atoms S 1. 57 grams sulfur is equal to how many atoms of sulfur? 57 grams S 1 mole S 32 grams S 6.02 X 1023 atoms S 1 mole S 3.43 X 1025 atoms S X X = 1.07 X 1024 atoms S 32

28. 1 mole S 32 grams S 6.02 X 1023 atoms S 1 mole S X X 2. How many atoms of Sulfur are in 100 grams of Sulfur? List given: 100 grams S = ? atoms S List conversions: 1 mole S = 32 grams S 1 mole S = 6.02 X 1023 atoms S Set Up: 6.02 X 1025 atoms S 100 grams S = 1.88 X 1024 atoms S 32

29. The Mole-Volume Relationship • gases - hard to determine mass • how many moles of gas? • 2 things affect gas Volume: • a) Temp & b) Pressure • compare all gases at = temp & pressure

30. Standard Temperature and Pressure • 0ºC & 1 atm pressure - abbreviated “STP” • At STP, 1 mol of any gas has V of 22.4 L - Called molar volume • 1 mol of any gas at STP = 22.4 L

31. Density of a gas • D = m / V (density = mass/volume) - for gas units are: g / L • find density of a gas at STP if formula known • You need: 1) mass and 2) volume • Assume 1 mol, so mass is molar mass (from periodic table) • At STP, V = 22.4 L

32. m = D x V • If given density, find molar mass of gas • Assume 1 mol at STP, so V = 22.4 L modify: D = m/V to show: • “m” will be mass of 1 mol, given 22.4 L

33. What is molar mass of a gas with density of 1.964 g/L? • How about a density of 2.86 g/L? = 44.0 g/mol 64.0 g/mol

34. Notice all conversions must go through the MOLE! Copy this conversion map into your notes!

35. That’s all Folks !