The MOLE

1) How much is in a pair? 2) How much is in a century? 3) How much is in a dozen?

IT IS A NUMBER OF ATOMS OR MOLECULES (OR VERY SMALL THINGS) To a chemist, it’s like a dozen of something but not x ,000,000,000,000,000,000,000 A mole is 6.02x 10 23

Avogadro’s number 6.02 x particles Volume of a STP 22.4 L Mass of 1 mole = g/mol depends on the substance off the Periodic Table 1 mole (mol) Density g/L

Atomic mass: measured in amu (atomic mass units) defined as 1/12 th of C-12 atomic mass = p + n ( p = 1 amu n = 1 amu ) Review 4 He 2 56 Fe 26 2 protons + 2 neutrons = 4 amu = 4 g/mol He p + 30 n = 56 amu = 56 g/mol

If we measure a mole of something, it will be heavy enough to put on a balance. Gram atomic mass off the Periodic Table, of 1 mole of atoms Gram formula mass for ionic bonds (like NaCl) Gram molecular mass for covalent bonds (molecules like H 2 O) ADD the masses off the P.T. Find the gram atomic mass of Na? Find the gram formula mass of NaCl? Find the gram molecular mass of H 2 O 23.0 g/mol = 58.5 g/mol = 18.0 g/mol All are molar masses

Avogadro’s Law Equal volumes of gases at the same temperature and pressure have equal numbers of particles. At STP, it is a mole or 6.02 x atoms or molecules depending on the gas. He or Ne would be atoms while CO 2 or F 2 would be molecules

1) Volume: 1 mole of CO 2 at STP = ____________22.4 L 2) Number of molecules of CO 2 : 1 mole = ________ 6.02 x molecules 3) Mass: 1 mole of CO 2 = _______________ = 44 g/mol There are 3 things we know about a mole. For example: Using the gas, carbon dioxide (CO 2 ) we know its volume, number of molecules and mass. 1) Volume: 1 mole of N 2 at STP = _______________ 2) Number of molecules of N 2 : 1 mole = __________ 3) Mass: 1 mole of N 2 = ___________ What changes between these 2 gases? ____________ 22.4 L 6.02 x molecules = 28 g/mol mass only

1. How many moles are in 25 grams of CO 2 2. How many grams would 42 moles of CO 2 mass? 3. How many moles are in 58 grams of N 2 ? 4. How many grams would 72 moles of N 2 mass?

1. How many moles are in 25 grams of CO 2 2. How many grams would 42 moles of CO 2 mass? 3. How many moles are in 58 grams of N 2 ? 4. How many grams would 72 moles of N 2 mass? X = 25 g 44 g.56818…. =.57 mol 42= X 44 g 1848 g = 1800 g X = 58 g 28 g …. = 2.1 mol 72 = X = 2.0 x 10 3 g

5. Balance the following equation and compute the masses of each. ____ KClO 3  ____ KCl + ____ O 2 ________ g  _______g + _______g 6. Balance the following equation and compute the masses of each. ____ C 3 H 8 + ____ O 2  ____ H 2 O + ____ CO 2 ______ g + _______g  _______g + _______g

5. Balance the following equation and compute the masses of each. ____ KClO 3  ____ KCl + ____ O 2 ________ g  _______g + _______g 6. Balance the following equation and compute the masses of each. ____ C 3 H 8 + ____ O 2  ____ H 2 O + ____ CO 2 ______ g + _______g  _______g + _______g

Per Cent Composition Part x 100 Whole % = ON REFERENCE TABLE The percentage composition of a compound gives the relative amount of each element present. In order to demonstrate how percentage composition is calculated, the percentage of each fruit in a fruit basket will be determined. Problem: The fruit basket contains 16g grapes, 43g oranges, 65g apples and 28g bananas. The total mass of the fruit basket is 152 grams. Calculate the percent of each fruit. What is the per cent of apples in the fruit basket? What is the per cent of bananas? What is the per cent of grapes? What is the per cent of oranges?

In determining the per cent composition of a chemical compound, the same process is followed. The mass of the element is divided by the gram molecular mass of the compound Problem: What is the per cent of oxygen in H 2 SO 4 ? % oxygen = Problem: Calculate the per cent of water (H 2 O ) in the hydrate: CuSO 4 H 2 O

1.NH 3 2. NaClO 3. NaCl 4. C 3 H 8 5. CuSO 4 5H 2 O

6. NaOH 7. C 2 H 6 O 2 8. CHCl 3

1.NH 3 2. NaClO 3. NaCl 4. C 3 H 8 N = 14 x 100 = 82% H = 3 x 100 = 18% Na = 23 x 100 = 31%, Cl = 35 x100 = 47% O = 16 x 100 = 22% Na = 23 x 100 = 40%, Cl = 35 x 100 = 60% C = 36 x 100 = 82%, H = 8 x 100 = 18% H 2 O = 90 x 100 = 36% CuSO 4 5H 2 O

6. NaOH 7. C 2 H 6 O 2 8. CHCl 3 Na = 23 x 100 = 58% O = 16 x 100 = 40% H = 1 x 100 = 2% 40 C = 24 x 100 = 39% H = 6 x 100 = 9% O = 32 x 100 = 52% C = 12 x 100 = 10% H = 1 x 100 =.8% Cl = 105 x 100 = 89%

SPICE 7.19 p Na 2 CO 3 = 106 g 2. C 4 H 10 = 58 g 3. KMnO 4 = 158 g 4. K 2 Cr 2 O 7 = 294 g.25 mol.63 g.083 mol 4.2 mol = X g = 450 g X = 14.5 g 58 g.004 mol = X 158 X = 24.5 g 294

SPICE 7.19 cont 1.5 mol = X 98 g 147 g = 150 g X = 15.5 g 310 g.05 =.050 mol 5. H 3 PO 4 = 98 g 6. Ca 3 (PO 4 ) 2 = 310 g

1.Empirical Formulas: Ionic Compounds: Example: NaCl Molecular compounds (covalent bonds) Example C 3 H 6 2. Circle the empirical formulas CH 4 C 2 H 4 C 6 H 6 N 2 O 5 NO 2 NO H 2 O 2 Simplest whole number ratio formula Use only empirical formulas since they are crystal structures The molecule can be the same as the empirical like H 2 O or different. Made up of molecules H – C = C – C – H H H H but its empirical formula is CH 2 H

Molecular Formulas (covalent compounds): Example true mass C 3 H 6 = ____ CH 2 = ____ empirical mass 3(12) + 6(1) = 1(12) +2(1) = = 3 (CH 2 ) 14 Given the empirical formula and the true mass, you can determine the molecular formula

Practice with Empirical Formula Problems When given the types of elements and either the mass of each element or the percent composition: change to moles 1. A 39 g sample of a gas contains 18 g of carbon and 21 g of nitrogen. What is its empirical formula? # of mol = given mass gram formula mass

Practice with Empirical Formula Problems When given the types of elements and either the mass of each element or the percent composition: change to moles 1. A 39 g sample of a gas contains 18 g of carbon and 21 g of nitrogen. What is its empirical formula? # of mol = 18 g 12 g nitrogen # of mol = 21 g 14 g carbon X = : 1 C N

2. A sample of a compound contains 24 grams of carbon and 64 grams of oxygen What is the empirical formula of this compound? (1) CO (2) CO 2 (3) C 2 O 2 (4) C 2 O 4 3. What is the empirical formula of a compound that contains 30.4% nitrogen and 69.6% oxygen by mass? (1)NO (2)NO 2 (3)N 2 O 3 (4)N 2 O 5

2. A sample of a compound contains 24 grams of carbon and 64 grams of oxygen What is the empirical formula of this compound? (1) CO (2) CO 2 (3) C 2 O 2 (4) C 2 O 4 3. What is the empirical formula of a compound that contains 30.4% nitrogen and 69.6% oxygen by mass? (1)NO (2)NO 2 (3)N 2 O 3 (4)N 2 O 5 # of mol = 24 g 12 g # of mol = 64 g 16 g 2 mol / 2 4 mol / 2 Divide by smallest # of moles CO 2 # of mol = 30.4 g # of mol = 69.6 g 14 g 16 g 2.17 / / 2.17 NO 2 carbon 1 2 nitrogen oxygen 1 : 2

4. A compound consists of 14.6% carbon and 85.4% chlorine by mass. What is the empirical formula? (1) CCl (2) CCl 2 (3) CCl 3 (4) CCl 4 5. Vitamin C has an empirical formula of C 3 H 4 O 3 and a molecular mass of 176 g/mol. What is the molecular formula of vitamin C? (1)C 3 H 4 O 3 (2)C 6 H 8 O 6 (3)C 9 H 12 O 9 (4)C 10 H 8 O 3

4. A compound consists of 14.6% carbon and 85.4% chlorine by mass. What is the empirical formula? (1) CCl (2) CCl 2 (3) CCl 3 (4) CCl 4 5. Vitamin C has an empirical formula of C 3 H 4 O 3 and a molecular mass of 176 g/mol. What is the molecular formula of vitamin C? (1)C 3 H 4 O 3 (2)C 6 H 8 O 6 (3)C 9 H 12 O 9 (4)C 10 H 8 O 3 # of mol = 14.6 # of mol = g mol / / 1.22mol CCl 2 12(3) + 4 (1) + 3 (16) = 88 g/mol 176 = 2 (C 3 H 4 O 3 ) C6H8O6C6H8O6 88 true weight empirical wt. 1 : 2

6. What is the molecular formula of a compound that has a molecular mass of 92 and an empirical formula of NO 2 (1)NO 2 (2)N 2 O 4 (3)N 3 O 6 (4)N 4 O 8 7. What is the molecular formula of a compound that has a molecular mass of 42 and an empirical formula of CH 2 (1)CH 2 (2)C 2 H 4 (3)C 3 H 6 (4)C 4 H 12

6. What is the molecular formula of a compound that has a molecular mass of 92 and an empirical formula of NO 2 (1)NO 2 (2)N 2 O 4 (3)N 3 O 6 (4)N 4 O 8 7. What is the molecular formula of a compound that has a molecular mass of 42 and an empirical formula of CH 2 (1)CH 2 (2)C 2 H 4 (3)C 3 H 6 (4)C 4 H (16) = 46 g/mol 92 = 2 (NO 2 ) = N 2 O 4 12(1) + 2(1) = 14 g/mol = 3 (CH 2 ) = C 3 H 6 14

8. If the empirical formula for an organic compound is CH 2 O, then the molecular mass of the compound could be (1) 135(2) 60(3) 45(4) 15

8. If the empirical formula for an organic compound is CH 2 O, then the molecular mass of the compound could be (1) 135(2) 60(3) 45(4) 15 CH 2 O = 12 (1) + 1 (2) + 16 (1) = 30 g/mol 30 (2) = (3) = (4) = (5) = 150

Hamburger Analogy  1 hamburger bun  2 hamburger patties  2 slices of cheese  4 strips of bacon 1.If I have five bacon double cheeseburgers _____ a) How many hamburger buns do I have _____b) How many hamburger patties do I have? _____c) How many slices of cheese do I have? _____d) How many strips of bacon do I have? 2. How many bacon double cheese burger can you make if you start with: ____a) 1 bun, 2 patties, 2 slices of cheese, 4 strips of bacon ____b) 2 buns, 4 patties, 4 slices of cheese, 8 strips of bacon

____c) 1 dozen buns, 2 dz patties, 2 dz slices of cheese, 4 dz strips of bacon ____d) 1 mole of buns, 2 moles of patties, 2 moles of cheese slices, 4 moles of bacon strips ____e) 10 buns, 20 patties, 2 slices of cheese, 40 bacon strips 3. Analyze the following & determine the limiting factor a)10 buns, 20 patties, 10 slices of cheese, 40 strips of bacon # of burgers ____ limiting factor ______ b) 12 buns, 20 patties, 20 slices of cheese, 40 strips of bacon # of burgers ____ limiting factor ______ c) 2 moles buns, 4 moles patties, 4 mole slices of cheese, 4 strips of bacon # of burgers ____ limiting factor ______ d).5 moles of buns, 1 mole of patties, 1 mole of cheese, 2 moles of bacon # of burgers ____ limiting factor ______

1 mole of H 2 SO moles NaOH  1 mole Na 2 SO mol H 2 O 4. If I want to make 5 moles of Na 2 SO 4 _________ a) How many moles of H 2 SO 4 do I need? ______b) How many moles of NaOH do I need? 5. How much Na 2 SO 4 can I make if I have ________ a) 1 mole of H 2 SO 4 and 2 mole of NaOH ________b)10 mole of H 2 SO 4 and 20 mole of NaOH ________c) 0.1 mole of H 2 SO 4 and 0.2 mole of NaOH ________d) 2 mole of H 2 SO 4 and 20 mole of NaOH limiting factor ____________ ________e) 2 mole of H 2 SO 4 and 1 mole of NaOH limiting factor _____________

1 H 2 SO NaOH  1 Na 2 SO H 2 O ______ g + ______ g  ______ g + ______ g MOLAR RATIOS Example: Fe 2 O 3 + 3CO  Fe + 3CO 2 The ratio of Fe 2 O 3 to CO is _____ The ratio of CO to CO 2 is ____ 6. N 2 + 3H 2  2NH 3 Ratio of N 2 to H 2 ______ and NH 3 to H 2 ______ 7. 2SO 2 + O 2  2SO 3 Ratio of O 2 to SO 2 ______and O 2 to SO 3 ______ 8. 4NH 3 + 3O 2  2N 2 + 6H 2 O Ratio for NH 3 to N 2 _______and H 2 O to O 2 _______

N 2 + 3H 2  2NH 3 I want to make 225 moles of ammonia. How many moles of nitrogen and hydrogen do I need? 225 mol X 1 = 2 X 225 2X = 225 X = X = mol of N 2 N 2 + 3H 2  2NH 3 X 225 mol mol of H

CALCULATIONS 1.Find the mass of the copper produced (c-a) 2.Calculate the number of moles of copper produced 3.Find the number of moles of iron reacted. 4.Find the whole number ratio of moles of iron to moles of copper Lab 29 Fe + CuSO 4