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CHEMICAL CALCULATIONS. Chapter 9 Section 2. Balanced Equations. Mole to Mole Calculations. Ratio of particles Ratio of moles Masses Most important is the ratio of moles This allows you to determine the number of moles of all substances in the reaction. Example. N 2 + 3H 2 2NH 3
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CHEMICAL CALCULATIONS Chapter 9 Section 2
Mole to Mole Calculations • Ratio of particles • Ratio of moles • Masses • Most important is the ratio of moles • This allows you to determine the number of moles of all substances in the reaction.
Example • N2 + 3H2 2NH3 • 1 mole of Nitrogen reacts with 3 moles of Hydrogen to produce 2 moles of NH3 (Ammonia) • Three mole ratios for this equation: • 1mol N2 : 3mol H2 • 2mol NH3 : 1mol N2 • 3mol H2 : 2mol NH3 • What are the other three mole ratios?
Example Continued • N2 + 3H2 2NH3 • How many moles of ammonia (NH3)are produced when 0.60 mol of nitrogen reacts with hydrogen? • Mole ratio for balanced equation 1:3:2 • Mole ratio for NH3 and N2 1:2
Example Continued • N2 + 3H2 2NH3
Check for understanding • Page 244 • #9 and 10
Mass to Mass calculations • Convert to moles of a reactant • Use mole ratio to convert to moles of a product • Convert back to grams to get grams of a product.
Example • N2 + 3H2 2NH3 • Calculate the number of grams of NH3 produced by the reaction of 5.40 g of hydrogen with excess of nitrogen. • gH2 molH2 mol NH3 gNH3
Other Stoichiometric Calculations • Page 247 • Any unit of measurement • Use Diagram • aG Given Quantity • bW Wanted Quantity
Pg. 248 Sample Problem • How many molecules of oxygen are produced when a sample of 29.2g of water is decomposed by electrolysis according to this balanced equation? • 2H2O 2H2 + O2
Pg. 248 Practice Problem • How many moleucles of oxygen are produced by the decomposition of 6.54g of potassium chlorate (KClO3)? • 2KClO3 2KCl + 3O2