Ch. 10 Stoichiometry GCC CHM 130

10.1 Interpreting a Chemical Equation 2 NO (g) + O 2 (g) → 2 NO 2 (g) 2 molecules 1 molecule 2 molecules 10 molecules 5 molecules 10 molecules 2 moles 1 mole 2 mole2 N 2 (g) + 3 H 2 (g) → 2 NH 3 (g) ___ molecule(s) ___ molecule(s) ___molecule(s) ____ mole ____ mole ____ mole So coefficients give us molecule or mole ratios.

10.2 Mole-Mole Ratios ___ Fe 2 O 3 (s) + ___ CO (g)  __ Fe (s) + ___CO 2 (g) 1 mol3 mol2 mol3 mol 1 mol Fe 2 O 3 3 mol CO Examples: 3 mol CO 1 mol Fe 2 O 3 3 mol CO 2 mol Fe 1.How many moles of iron can be formed from 10.2 moles of carbon monoxide? 2.How many moles of iron(III) oxide are needed to form 17 moles of carbon dioxide? 17 mol CO 2 ( 1 mol Fe 2 O 3 / 3 mole CO 2 ) = 5.7 mol Fe 2 O mol CO ( 2 mol Fe / 3 mole CO) = 6.80 mol Fe

Another Example Balance this reaction: ___ SO 2 (g) + ___O 2 (g)  ___SO 3 (g) How many moles of SO 3 will form if moles of oxygen gas react? How many moles of SO 2 are needed to make moles of sulfur trioxide? mol O 2 (2 mol SO 3 / 1 mol O 2 ) = mol SO mol SO 3 (2 mol SO 2 / 2 mol SO 3 ) = mol SO2

Mass – Mass Stoichiometry Grams given Moles given Moles find Grams find Molar Mass Molar Mass Mole Ratio 3 FeO(s) + 2 Al(s)  3 Fe(s) + Al 2 O 3 (s) 1.Calculate the mass of iron (II) oxide needed to react completely with 5.55 g of aluminum. 2.Calculate the mass of aluminum oxide produced when g of aluminum reacts completely.

g Al = 22.2 g FeO g Al = g Al 2 O 3 3 FeO(s) + 2 Al(s)  3 Fe(s) + Al 2 O 3 (s)

Mass – Volume and Volume-Volume problems

Write and balance the reaction of HCl (aq) and solid cobalt. Note cobalt will be +2 as an ion in this example. How many liters of gas at STP will form if 5.00 grams of cobalt reacts? If L of hydrogen gas formed, how many grams of HCl reacted? 5.00 g Co(mol/58.93)(1 molH 2 /1molCo)(22.4L/mol) = 1.90 L H L H 2 (mol/22.4L)(2 mol HCl/1 mol H 2 )(36.46 g/mol) = 7.73 g HCl 2 HCl(aq) + Co(s)  CoCl 2 (aq) + H 2 (g)

HCl gas plus oxygen gas produces chlorine gas and water vapor. How many liters of chlorine can be formed if 3.00 liters of oxygen react completely at STP? 4 HCl(g) + O 2 (g)  2 Cl 2 (g) + 2 H 2 O(g) 3.00 L O 2 (mol / 22.4 L)(2 mol Cl 2 / 1 mol O 2 )(22.4 L/mol) = 6.00 L Cl 2

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Try at Home Carbon reacts with oxygen gas to form carbon monoxide. How many liters of carbon monoxide at STP can be made from grams carbon? liters of oxygen gas? Remind me to show answers next time 2 C(s) + O 2 (g)  2 CO(g) 15.0 g C (mol /12.01g)(2 mol CO/2 mol C)(22.4 L / mol)= 28.0 L CO 20.0 L O 2 (mol /22.4L)(2 mol CO /1 mol O 2 )(22.4 L/mol)= 40.0 L CO

Self Test Page 288 Try 1-6, 10, 14 Answers in Appendix J