CHAPTER 7 CHEMICAL FORMULA
Remember… The Mole Is a Counting Unit The mole is used to count out a given number of particles (atoms, molecules, formula units, ions, or electrons) The mole is just one kind of counting unit: 1 dozen = 12 objects 1 hour = 3600 seconds 1 mole = particles
Visual Concepts The Mole Chapter 7
Calculating Molar Mass Also known as: Gram Formula Mass G.F.M.
Molar Mass How much the compound weighs Just add everything up using the mass from the P.T. Example:
Molar Mass ZnCl 2 = Zn + 2 Cl = (35.45) = = g / mol ZnSO 4 = Zn + S + 4 Oxy = (65.39) + (32.07) + 4 (16.00) = g / mol
Molar Mass (NH 4 ) 2 SO 4 = 2 N + 8 H + S + 4 Oxy = 2(14.01) + 8 (1.01) (16.00) = = g / mol
Mol – g Conversions Using Molar Masses
Molar Mass Conversions Sample Problem A: How many grams are in 2.50 mol of oxygen gas, O 2 ?
Molar Mass Conversions Sample Problem A: How many grams are in 2.50 mol of oxygen gas, O 2 ? Step 1: Start with what you know from the problem mol O 2 = X g
Molar Mass Conversions Sample Problem A: How many grams are in 2.50 mol of oxygen gas, O 2 ? Step 2: Determine the molar mass of your compound. O 2 = 2 Oxy 2 (16.00) 1 mol = g
Molar Mass Conversions Sample Problem A: How many grams are in 2.50 mol of oxygen gas, O 2 ? Step 3: Set – up the problem so the units cancel out mol O 2 = X g 1 mol g X = 80.0 g
Sample Problem B Ibuprofen, C 13 H 18 O 2, is the active ingredient in many nonprescription pain relievers. Its molar mass is g/mol. If the tablets in a bottle contain a total of 33 g of ibuprofen, how many moles of ibuprofen are in the bottle?
Sample Problem B Ibuprofen, C 13 H 18 O 2, is the active ingredient in many nonprescription pain relievers. Its molar mass is g/mol. If the tablets in a bottle contain a total of 33 g of ibuprofen, how many moles of ibuprofen are in the bottle? Step 1: Start with what you know from the problem. 33 g C 13 H 18 O 2 = X mol
Sample Problem B Ibuprofen, C 13 H 18 O 2, is the active ingredient in many nonprescription pain relievers. Its molar mass is g/mol. If the tablets in a bottle contain a total of 33 g of ibuprofen, how many moles of ibuprofen are in the bottle? Step 2: Determine the molar mass of the compound g = 1 mol
Sample Problem B Ibuprofen, C 13 H 18 O 2, is the active ingredient in many nonprescription pain relievers. Its molar mass is g/mol. If the tablets in a bottle contain a total of 33 g of ibuprofen, how many moles of ibuprofen are in the bottle? Step 3: Set-up the problem so the units cancel out. 33 g C 13 H 18 O 2 = X mol g 1 mol X = 0.16 mol C 13 H 18 O 2
Mole – Mass Conversions Team Review
Question # 1 Calculate the molar mass of barium nitrate. Ba(NO 3 ) g / mol
Question #2 Calculate the molar mass of lithium nitride. Li 3 N g / mol
Question # 3 Calculate the molar mass of magnesium phosphate. Mg 3 (PO 4 ) g / mol
Question # 4 Calculate the molar mass of iron (III) oxide. Fe 2 O g / mol
Question #5 How many moles are found in 100. g of barium nitrate? mol Ba(NO 3 ) 2
Question # 6 How many moles are found in 24.3 g of lithium nitride? mol Li 3 N
Question # 7 What is the mass found in 2.25 mol iron (III) oxide? g Fe 2 O 3
Question # 8 What is the mass found in 1.30 mol magnesium phosphate? g Mg 3 (PO 4 ) 2
Question # 9 How many molecules are found in 6.4 mol NH 3 ? 3.85 x molecules NH 3
Question # 10 How many moles are found in 1.85 x molecules of water? 3.07 mol H 2 O
Question # 11 What is the mass of 2.30 x molecules of CO 2 ? g CO 2
Question # 12 How many molecules are found in 25 g N 2 ? 5.37 x molecules of N 2
Percent Composition
Visual Concepts Percentage Composition Chapter 7
Percent Composition
Sample Problem C Find the percent composition of copper (I) sulfide, Cu 2 S.
Sample Problem C Find the percent composition of copper (I) sulfide, Cu 2 S. Step 1: Use the formula to determine the molar mass of the compound. Cu 2 S = 2 Cu + S 2 (63.55) g / mol
Sample Problem C Find the percent composition of copper (I) sulfide, Cu 2 S. Step 2: Determine the % composition of the 1 st element. Cu = mass of Cu x 100 Total molar mass
Sample Problem C Find the percent composition of copper (I) sulfide, Cu 2 S. Step 3: Determine the % composition of the 2 nd element. S = mass of S x 100 Total molar mass
Class Quiz
Chapter 7 Standardized Test Preparation Multiple Choice 1.Which of the following compounds does not contain a polyatomic ion? A.sodium carbonate B.sodium sulfate C.sodium sulfite D.sodium sulfide
Chapter 7 Standardized Test Preparation Multiple Choice 2.The correct formula for ammonium phosphate is A.(NH 4 ) 3 PO 4. B.(NH 4 ) 2 PO 4. C.NH 4 PO 4. D.NH 4 (PO 4 ) 2.
Chapter 7 Standardized Test Preparation Multiple Choice 3.When writing the formula for a compound that contains a polyatomic ion, A.write the anion’s formula first. B.use superscripts to show the number of polyatomic ions present. C.use parentheses if the number of polyatomic ions is greater than 1. D.always place the polyatomic ion in parentheses.
Chapter 7 Standardized Test Preparation 4.The correct name for NH 4 CH 3 COO is A.ammonium carbonate. B.ammonium hydroxide. C.ammonium acetate. D.ammonium nitrate. Multiple Choice
Chapter 7 Standardized Test Preparation 5.Which of the following is the correct formula for iron(III) sulfate? A.Fe 3 SO 4 B.Fe 3 (SO 4 ) 2 C.Fe 2 (SO 4 ) 3 D.3FeSO 4 Multiple Choice
Chapter 7 Standardized Test Preparation Multiple Choice 1.Which of the following compounds does not contain a polyatomic ion? A.sodium carbonate B.sodium sulfate C.sodium sulfite D.sodium sulfide
Chapter 7 Standardized Test Preparation Multiple Choice 2.The correct formula for ammonium phosphate is A.(NH 4 ) 3 PO 4. B.(NH 4 ) 2 PO 4. C.NH 4 PO 4. D.NH 4 (PO 4 ) 2.
Chapter 7 Standardized Test Preparation Multiple Choice 3.When writing the formula for a compound that contains a polyatomic ion, A.write the anion’s formula first. B.use superscripts to show the number of polyatomic ions present. C.use parentheses if the number of polyatomic ions is greater than 1. D.always place the polyatomic ion in parentheses.
Chapter 7 Standardized Test Preparation 4.The correct name for NH 4 CH 3 COO is A.ammonium carbonate. B.ammonium hydroxide. C.ammonium acetate. D.ammonium nitrate. Multiple Choice
Chapter 7 Standardized Test Preparation 5.Which of the following is the correct formula for iron(III) sulfate? A.Fe 3 SO 4 B.Fe 3 (SO 4 ) 2 C.Fe 2 (SO 4 ) 3 D.3FeSO 4 Multiple Choice