The Mole Concept - GENERAL CHEMISTRY FOR SHS

It presents the concept of mole required to understand chemical reactions.

1. Overview of food energy flow through the body for maintenance of energy balance

2. Eggs, meat products, milk products: Protein kcal/g (kJ/g) § Fat kcal/g (kJ/g) § Total carbohydrate kcal/g (kJ/g) § Eggs 4.36  (18.2) 9.02  (37.7) 3.68  (15.4) Meat/fish 4.27  (17.9) 9.02  (37.7) * Milk/milk products 4.27  (17.9) 8.79  (36.8) 3.87  (16.2)

3. Chemistry is a qitantivuate science.

4. Chemistry is a quantitative science.

5. The Mole Concept

6. Atoms are the building blocks of matter and they occupy space and have mass.

7. Masses of atoms are measured in atomic mass unit ( amu ) using a device called spectrometer.

8. Spectrometer is used in determining the average atomic mass of an element that can be found on the periodic table.

9. Elements Atomic Mass Unit Li 6.941 C 12.01

10. Isotopes Isotopes are atoms of the same element (same number of proton and electron) that differ in the number of neutrons. They also differ in their mass number.

11. Computing for the Average Atomic Mass 1. Multiply each atomic mass with their percentage abundance.

12. Computing for the Average Atomic Mass 2. Get the sum of the product (Round off to three decimal places.)

13. Magnesium has 3 isotopes, 78.70% of magnesium exist as Mg-24 (23.9850 amu ); 10.03 % exist as Mg-25 (24.9858 amu ) and 11.17 % exist as Mg-26 (25.9826 amu ). What is the average atomic mass of magnesium?

14. Gallium has two naturally occurring isotopes. The mass of gallium-69 is 68.9256 amu and it is 60.108% abundant. The mass of gallium-71 is 70.9247 amu and it is 39.892% abundant. Calculate the atomic mass of gallium.

15. Carbon has two isotopes, carbon-12 and carbon-13. Their atomic masses are 12.00000 and 13.00335 and their percent abundance are 98.89 and 1.11, respectively. What is the average atomic mass of carbon? Show your computation.

16. Copper exists as a mixture of two isotopes. Copper-63 is 69.17% abundant and it has a mass of 62.9296 amu . Copper-65 is 30.83% abundant and it has a mass of 64.9278 amu . Calculate the atomic mass of copper.

17. HOMEWORK Calculate the atomic mass of lead. The four lead isotopes have atomic masses and relative abundances of 203.973 amu (1.4%), 205.974 amu (24.1%), 206.976 amu (22.1%) and 207.977 amu (52.4%).

18. HOMEWORK Bromine has two naturally occurring isotopes. Bromine-79 has a mass of 78.918 amu and is 50.69% abundant. Using the atomic mass reported on the periodic table, determine the mass of bromine-81, the other isotope of bromine.

19. CONVERSION FACTOR

20. The mole (mole) is the amount of substance that contains as many elementary entities ( atoms, molecules, or other particles ) as there are atoms in exactly 12 g of the carbon-12 isotope.

21. 1 mole of an atom = ____ grams 1 mole of an atom = atoms ____ grams = atoms  

22. ATOMS AND MOLECULES g ram to mole atom to mole g ram to atom

23. GRAM TO MOLE How many moles of helium atoms are in 1.1 g of a medium-sized balloon? Assume negligible weight of the balloon itself.

24. GRAM TO MOLE How many moles are in 15 grams of lithium?

25. GRAM TO MOLE How many moles are in 22 grams of argon?

26. GRAM TO MOLE - HOMEWORK How many moles are in 2.3 grams of phosphorus?

27. ATOM TO MOLE How many moles of silver are in silver atoms?  

28. ATOM TO MOLE How many moles of nickel (Ni) is atoms of nickel?  

29. ATOM TO MOLE - HOMEWORK If you have atoms of chromium (Cr), how many moles of chromium do you have?  

30. GRAMS TO ATOMS How many gold atoms are present in a piece of gold ring weighing 39.0 g?

31. GRAMS TO ATOMS How many atoms are there in 16.5 g of Mg?

32. GRAMS TO ATOMS How many atoms are there in 12 g of Al?

33. GRAMS TO ATOMS - HOMEWORK How many atoms are there in 24 g of Fe?

34. The ________ possible ________ of a particular substance that has all the ________ of that substance

35. The smallest possible amount of a particular substance that has all the characteristics of that substance

36. Molecule is the smallest possible amount of a particular substance that has all the characteristics of that substance.

37. MOLECULES AND MOLES Molar Mass Converting grams to molecules

38. MOLECULES AND MOLES 1 mole of a compound= molecules 1 mole of a compound= MOLAR MASS in grams  

39. MOLAR MASS Refers to the sum of the masses of the elements present in the compound NOTE: Atomic mass = g Molar mass = g/ mol

40. Computing for Molar mass Determine the number of atoms of each element in a compound.

41. Computing for Molar mass Multiply the number of atoms to their atomic mass.

42. Computing for Molar mass Get the sum of the products (g/ mol ).

43. Computing for Molar mass Determine the molar mass of HCl .

44. Computing for Molar mass Determine the molar mass of .  

45. Computing for Molar mass Determine the molar mass of sucrose ( ).  

46. Computing for Molar mass Determine the molar mass of sulfur dioxide .

47. Computing for Molar mass Calculate the molar mass of methanol ( ).  

48. Molar mass - HOMEWORK Calculate the molar mass of caffeine ( ).  

49. MOLECULES AND MOLES Molar Mass Converting grams to molecules

50. MOLECULES AND MOLES A small bottle of distilled water contains 120.0 g of molecules. How many molecules of are present in the bottles of distilled water?  

51. MOLECULES AND MOLES How many molecules of are there in 25.8 g?  

52. MOLECULES AND MOLES How many molecules are there in 2.35 mole s of ?  

53. MOLECULES AND MOLES - HOMEWORK How many molecules of are there in a 24.5 g sample of ?  

54. Why are conversion factors important in Chemistry?

55. CHEMICAL REACTION

56. What happens to the intensity of the fire produced inside the containers when the alcohol concentration of the liquid was increased?

57. MASS PERCENTAGE COMPOSITION

58. MASS PERCENTAGE COMPOSITION

59. MASS PERCENTAGE COMPOSITION Shows the composition of compounds in terms of chemical symbols present

60. MASS PERCENTAGE COMPOSITION Find the mass of each element. Determine the molar mass of the compound.

61. MASS PERCENTAGE COMPOSITION Calculate the mass percentage composition using the formula:  

62. MASS PERCENTAGE COMPOSITION Ethyl alcohol as ethanol, , is a colorless and volatile liquid found in alcoholic beverages. What is the percentage of each element in ethanol?  

63. MASS PERCENTAGE COMPOSITION Washing soda, , is used in the manufacture of glass and paper. Calculate the percentage composition of washing soda.  

64. Challenge: Identify the right word/s or number that will complete the table.

65. Compound Ethyl Alcohol Chemical Formula C 2 H 5 OH Molar Mass 46.08 g/ mol % comp of O SAMPLE

66. Compound Ethyl Alcohol Chemical Formula C 2 H 5 OH Molar Mass 46.08 g/ mol % comp of O 34.72 % SAMPLE

67. Compound Ethyl Alcohol Chemical Formula C 2 H 5 OH Molar Mass 46.08 g/ mol % comp of C 1

68. Compound Ethyl Alcohol Chemical Formula C 2 H 5 OH Molar Mass 46.08 g/ mol % comp of C 52.13 % 1

69. Compound Baking Soda Chemical Formula NaHCO 3 Molar Mass 84.01 g/ mol % comp of H 2

70. Compound Baking Soda Chemical Formula NaHCO 3 Molar Mass 84.01 g/ mol % comp of H 1.20 % 2

71. Compound Bleach Chemical Formula NaClO Molar Mass 74.44 g/ mol % comp of Cl 3

72. Compound Bleach Chemical Formula NaClO Molar Mass 74.44 g/ mol % comp of Cl 47.62 % 3

73. Compound Aspirin Chemical Formula C 9 H 8 O 4 Molar Mass % comp of C 59.99 % 4

74. Compound Aspirin Chemical Formula C 9 H 8 O 4 Molar Mass 180.17 g/ mol % comp of C 59.99 % 4

75. Compound Chalk Chemical Formula CaCO 3 Molar Mass 100.09 g/ mol % comp of Cl 5

76. Compound Chalk Chemical Formula CaCO 3 Molar Mass 100.09 g/ mol % comp of Cl % 5

77. Compound Milk of Magnesia Chemical Formula Mg(OH) 2 Molar Mass 58.33 g/ mol 54.86 % 6

78. Compound Milk of Magnesia Chemical Formula Mg(OH) 2 Molar Mass 58.33 g/ mol % comp of O 54.86 % 6

79. Compound Milk of Magnesia Chemical Formula Mg(OH) 2 Molar Mass 58.33 g/ mol % comp of O 54.86 % 6

80. Compound Milk of Magnesia Chemical Formula Molar Mass 58.33 g/ mol % comp of O 54.86 % 6

81. EMPIRICAL FORMULA Shows the simplest ratio of atoms present in a compound

82. EMPIRICAL FORMULA Change the given percent to grams Convert grams to moles

83. EMPIRICAL FORMULA Divide each number of moles by the smallest number of computed moles

84. EMPIRICAL FORMULA An acid commonly used in the automobile industry is shown to be 3.1 % hydrogen, 31.6 % phosphorus, and 63.5 % oxygen. Determine the empirical formula of this acid.

85. EMPIRICAL FORMULA What is the empirical formula of compound containing 70.19 % lead, 8.14 % carbon, and 21.67 % oxygen?

86. EMPIRICAL FORMULA - HOMEWORK A compound is found to have 46.67% nitrogen, 6.70% hydrogen, 19.98% carbon and 26.65% oxygen. What is its empirical formula?

87. MOLECULAR FORMULA Gives the actual number of atoms of each element per molecule

88. MOLECULAR FORMULA Calculate the molar mass of the given empirical formula

89. MOLECULAR FORMULA Divide the given mass of the compound by its molar mass. Let n be their quotient.

90. MOLECULAR FORMULA Derive the molecular formula by: MF = (EF)(n)

91. MOLECULAR FORMULA If the empirical formula of an unknown compound is and its molar mass is 181g/ mol , what is the molecular formula of the compound?  

92. MOLECULAR FORMULA What is the molecular formula of a compound with a molar mass of 860 g/ mol and its empirical formula is ?  

93. MOLECULAR FORMULA - HOMEWORK Another compound, also with an empirical formula if CH is found to have a molar mass of 26.04 g/mol. What is its molecular formula?

94. CHALLENGE PROBLEM A compound is analyzed and found to contain 68.54% carbon, 8.63% hydrogen, and 22.83% oxygen.  If the molecular weight of this compound is known to be approximately 140 g/mol. What is its molecular formula? 

95. CHALLENGE PROBLEM An unknown compound was found to have a percent composition as follows: 47.0 % potassium, 14.5 % carbon, and 38.5 % oxygen. If the molar mass of the compound is 166.22 g/ mol , what is its molecular formula ?

96. PRACTICE PROBLEMS

97. PRACTICE PROBLEM #1 Calculate the mass percentage composition of the compound, HCN.

98. PRACTICE PROBLEM #2 Calculate the mass percentage composition of the compound, NaHSO 4 .

99. PRACTICE PROBLEM #3 Calculate the mass percentage composition of nitrogen in the compound, NH 4 NO 3 .

100. PRACTICE PROBLEM #4 Calculate the empirical formula of the compound with the following percent composition: 94.1 % O, 5.9% H.

101. PRACTICE PROBLEM #5 The percent composition is found to have the following % composition: 68.4% Cr and 31.6 % O. Determine the compound’s empirical formula.