1. HW answers

2. E-16 Notes Part 2

3. Two Step Example (already done)
Determine the mass of 2.0x1022 molecules CO2

4. Two Step Example (already done)
Determine the mass of 2.0x1022 molecules CO2
Write down what you know:

5. Two Step Example (already done)
Determine the mass of 2.0x1022 molecules CO2
Write down what you know:
2.0x1022 molecules CO2

6. Two Step Example (already done)
Determine the mass of 2.0x1022 molecules CO2
2.0x1022 molecules CO2
You must change to moles!

7. Two Step Example (already done)
Determine the mass of 2.0x1022 molecules CO2
2.0x1022 molecules CO2
How many molecules are in one mole?

8. Two Step Example (already done)
Determine the mass of 2.0x1022 molecules CO2
2.0x1022 molecules CO2
1 mole = x 1023 molecules

9. Two Step Example (already done)
Determine the mass of 2.0x1022 molecules CO2
2.0x1022 molecules CO2
Since you are starting with molecules, then x1023 molecules must be in the denominator!

10. Two Step Example (already done)
Determine the mass of 2.0x1022 molecules CO2
2.0x1022 molecules CO2
Remember that you must have the same label in the denominator as the original label.

11. Two Step Example (already done)
Determine the mass of 2.0x1022 molecules CO2
2.0x1022 molecules CO2
Next we have the change from moles to mass:
How do you change from moles to mass????

12. Two Step Example (already done)
Determine the mass of 2.0x1022 molecules CO2
2.0x1022 molecules CO2
Next we have the change from moles to mass:
How do you change from moles to mass????
USE THE MOLAR MASS!!!!!

13. WHAT IS THE MOLAR MASS OF CO2?
USE THE PERIODIC TABLE!

14. WHAT IS THE MOLAR MASS OF CO2?
USE THE PERIODIC TABLE!
1 Carbon + 2 Oxygen =

15. WHAT IS THE MOLAR MASS OF CO2?
USE THE PERIODIC TABLE!
1 Carbon + 2 Oxygen =
(16.00) = g/mole

16. Two Step Example (already done)
Determine the mass of 2.0x1022 molecules CO2
2.0x1022 molecules
So we need to change from moles to mass. The
“1 mole” must be in the denominator to cancel out:

17. Two Step Example (already done)
Determine the mass of 2.0x1022 molecules CO2
2.0x1022 molecules
We must put the molar mass on top and the 1 mole in the denominator to make the mole label cancel!

18. Two Step Example (already done)
Determine the mass of 2.0x1022 molecules CO2
2.0x1022 molecules
Use your calculator to get the answer:
Remember to divide by denominators and multiply by numerators!

19. Two Step Example (already done)
Determine the mass of 2.0x1022 molecules CO2
2.0x1022 molecules
The answer is 1.5 g CO2
Make sure your sig. figs. match the given number!

20. More examples #1
What is the mass of 2.25 L of CO2 at STP?

21. More examples #1 What is the mass of 2.25 L of CO2 at STP?
Write down what you know:

22. More examples #1 What is the mass of 2.25 L of CO2 at STP?
Write down what you know:
2.25 L CO2

23. More examples #1 What is the mass of 2.25 L of CO2 at STP? 2.25 L CO2
You must change to moles!

24. More examples #1 What is the mass of 2.25 L of CO2 at STP? 2.25 L CO2
Ask yourself: “How many liters are in one mole?”

25. More examples #1 What is the mass of 2.25 L of CO2 at STP? 2.25 L CO2
22.4 L equals one mole!

26. More examples #1 What is the mass of 2.25 L of CO2 at STP? 2.25 L CO2
Remember that you must have the same label in the denominator as the original label.
* 1 mole contains 22.4 L of any gas at STP!!

27. More examples #1 What is the mass of 2.25 L of CO2 at STP? 2.25 L CO2
Next we have the change from moles to mass:
How do you change from moles to mass????

28. More examples #1 USE THE MOLAR MASS!!!!!
What is the mass of 2.25 L of CO2 at STP?
2.25 L CO2
USE THE MOLAR MASS!!!!!

29. WHAT IS THE MOLAR MASS OF CO2?
USE THE PERIODIC TABLE!

30. WHAT IS THE MOLAR MASS OF CO2?
USE THE PERIODIC TABLE!
1 Carbon + 2 Oxygen =

31. WHAT IS THE MOLAR MASS OF CO2?
USE THE PERIODIC TABLE!
1 Carbon + 2 Oxygen =
(16.00) = g/mole

32. More examples #1
What is the mass of 2.25 L of CO2 at STP?
2.25 L CO2
So, we need to change to mass, so the 1 mole goes on the bottom.

33. More examples #1 What is the mass of 2.25 L of CO2 at STP? 2.25 L CO2
So now we have the change from moles to mass:

34. More examples #1 What is the mass of 2.25 L of CO2 at STP? 2.25 L CO2
We must put the molar mass on top and the 1 mole in the denominator to make the mole label cancel!

35. More examples #1 What is the mass of 2.25 L of CO2 at STP? 2.25 L CO2
Use your calculator to get the answer:
Remember to divide by denominators and multiply by numerators!

36. More examples #1 What is the mass of 2.25 L of CO2 at STP? 2.25 L CO2
The answer is 4.42 g CO2
* Make sure your sig. figs. match the given number!

37. More examples #2
What is the volume of 1.31 g of methane, CH4?

38. More examples #2 What is the volume of 1.31 g of methane, CH4?
Write down what you know:

39. More examples #2 What is the volume of 1.31 g of methane, CH4?
Write down what you know:
1.31 g CH4

40. More examples #2 What is the volume of 1.31 g of methane, CH4?
1.31 g CH4
You must change to moles!

41. More examples #2 What is the volume of 1.31 g of methane, CH4?
1.31 g CH4
Remember that you must have the same label in the denominator as the original label.

42. More examples #2 What is the volume of 1.31 g of methane, CH4?
1.31 g CH4
How do you change between moles and mass?

43. More examples #2 What is the volume of 1.31 g of methane, CH4?
1.31 g CH4
USE MOLAR MASS!!

44. WHAT IS THE MOLAR MASS OF CH4?
USE THE PERIODIC TABLE!

45. WHAT IS THE MOLAR MASS OF CH4?
USE THE PERIODIC TABLE!
1 Carbon + 4 hydrogen =

46. WHAT IS THE MOLAR MASS OF CH4?
USE THE PERIODIC TABLE!
1 Carbon + 4 hydrogen
(1.01) = g/mole

47. More examples #2 What is the volume of 1.31 g of methane, CH4?
1.31 g CH4
* The molar mass number goes in the denominator to cancel out the gram label.

48. More examples #2 What is the volume of 1.31 g of methane, CH4?
1.31 g CH4
Next we have the change from moles to volume

49. More examples #2 What is the volume of 1.31 g of methane, CH4?
1.31 g CH4
What is the volume of one mole of gas?

50. More examples #2 What is the volume of 1.31 g of methane, CH4?
1.31 g CH4
1 mole contains 22.4 L of gas!

51. More examples #2 What is the volume of 1.31 g of methane, CH4?
1.31 g CH4
Use your calculator to get the answer:
Remember to divide by denominators and multiply by numerators!

52. More examples #2 What is the volume of 1.31 g of methane, CH4?
1.31 g CH4
The answer is 1.83 L CH4
Make sure your sig. figs. match the given number!

53. Example #3 How many molecules in 2.15 g of AgNO3?
Write down what you know:
2.15 g AgNO3

54. Example #3 How many molecules in 2.15 g of AgNO3?
How do you change grams to moles?
2.15 g AgNO3
Use the molar mass
What is the molar mass of AgNO3?
1 Ag + 1 N + 3 O =
(16.00)= g

55. Example #3 How many molecules in 2.15 g of AgNO3?
What goes on the top of the fraction?
2.15 g AgNO3
We need grams to cancel! So 1 mole goes on top and the molar mass is in the denominator.
g = 1 mole

56. Example #3 How many molecules in 2.15 g of AgNO3?
What goes on the top of the fraction?
2.15 g AgNO3
We need grams to cancel! So 1 mole goes on top and the molar mass is in the denominator.

57. Example #3 How many molecules in 2.15 g of AgNO3?
How many molecules are in one mole?
2.15 g AgNO3
There are x 1023 molecules in a mole.
We need moles to cancel! So 1 mole goes on bottom and the x 1023 molecules is in the numerator.

58. Example #3 How many molecules in 2.15 g of AgNO3?
Use your calculator to get the answer!
2.15 g AgNO3
There are 7.62 x 1021 molecules of AgNO3

59. Example #4 What is the mass of 1.30x1021 atoms of C?
Write down what you know:
1.30x1021 atoms of C

60. Example #4 What is the mass of 1.30x1021 atoms of C?
How do you change to moles?
1.30x1021 atoms of C
How many atoms are in one mole?
6.022 x 1023 atoms = 1 mol

61. Example #4 What is the mass of 1.30x1021 atoms of C?
What goes on the top of the fraction?
1.30x1021 atoms of C
We need atoms to cancel! So 1 mole goes on top and the 6.022x1023 is in the denominator.

62. Example #4 What is the mass of 1.30x1021 atoms of C?
What goes on the top of the fraction?
1.30x1021 atoms of C
We need atoms to cancel! So 1 mole goes on top and the 6.022x1023 is in the denominator.

63. Example #4 What is the mass of 1.30x1021 atoms of C?
How many grams are in one mole of C?
1.30x1021 atoms of C
There are g of Carbon in a mole.
We need moles to cancel! So 1 mole goes on bottom and the g is in the numerator.

64. Example #4 What is the mass of 1.30x1021 atoms of C?
Use your calculator to get the answer!
1.30x1021 atoms of C
There are g of Carbon in a mole.
We need moles to cancel! So 1 mole goes on bottom and the g is in the numerator.
There are g of Carbon

65. Example #5 What is the volume of 1.30x1021 atoms of Ar?
Write down what you know:
1.30x1021 atoms of Ar

66. Example #5 What is the volume of 1.30x1021 atoms of Ar?
How do you change to moles?
1.30x1021 atoms of Ar
How many atoms are in one mole?
6.022 x 1023 atoms = 1 mol

67. Example #5 What is the volume of 1.30x1021 atoms of Ar?
What goes on the top of the fraction?
1.30x1021 atoms of Ar
We need atoms to cancel! So 1 mole goes on top and the 6.022x1023 is in the denominator.

68. Example #5 What is the volume of 1.30x1021 atoms of Ar?
What goes on the top of the fraction?
1.30x1021 atoms of Ar
We need atoms to cancel! So 1 mole goes on top and the 6.022x1023 is in the denominator.

69. Example #5 What is the volume of 1.30x1021 atoms of Ar?
How many liters are in one mole of Ar?
1.30x1021 atoms of Ar
There are 22.4 L in one mole.
We need moles to cancel! So 1 mole goes on bottom and the 22.4 L is in the numerator.

70. Example #5 What is the volume of 1.30x1021 atoms of Ar?
Use your calculator to get the answer!
1.30x1021 atoms of Ar
There are 22.4 L in one mole.
We need moles to cancel! So 1 mole goes on bottom and the 22.4 L is in the numerator.
There are L of Ar

71. Example #6 How many molecules in 0.54 L of H2 gas at STP?
Write down what you know:
0.54 L of H2

72. Example #6 How many molecules in 0.54 L of H2 gas at STP?
How do you change to moles?
0.54 L of H2
How many liters of gas in one mole?
22.4 L = 1 mol

73. Example #6 How many molecules in 0.54 L of H2 gas at STP?
What goes on the top of the fraction?
0.54 L of H2
We need liters to cancel! So 1 mole goes on top and the 22.4 L is in the denominator.
22.4 L = 1 mol

74. Example #6 How many molecules in 0.54 L of H2 gas at STP?
What goes on the top of the fraction?
0.54 L of H2
We need liters to cancel! So 1 mole goes on top and the 22.4 L is in the denominator.

75. Example #6 How many molecules in 0.54 L of H2 gas at STP?
How many molecules are in one mole?
0.54 L of H2
There are 6.022x1023 molecules in one mole.
We need moles to cancel! So 1 mole goes on bottom and the 6.022x1023 molecules is in the numerator.

76. Example #6 How many molecules in 0.54 L of H2 gas at STP?
Use your calculator to get the answer!
0.54 L of H2
There are 6.022x1023 molecules in one mole.
We need moles to cancel! So 1 mole goes on bottom and the 6.022x1023 molecules is in the numerator.
There are 1.5 x 1022 molecules of H2

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