Presentation on theme: "CA Standards Std. 3e: Students know how to calculate the masses of reactants and products in a chemical reaction from the mass of one of the reactants."— Presentation transcript:
1 CA StandardsStd. 3e: Students know how to calculate the masses of reactants and products in a chemical reaction from the mass of one of the reactants or products and the relevant atomic masses.
2 What is Stoichiometry?The study of quantities of materials consumed and produced in chemical reactions.
3 How Are Stoich Problems Different? Includes a balanced equation and molar conversions.Coefficient of equation shows molar relationship (Mole ratio) of reactants and products.Ex: 2H2 + O2 2H2O2 mol H mol O2 2 mol H2OEx: Mole Ratio of H2: H2O 2 mol H22 mol H2O
4 Calculating Masses of Reactants and Products Check if equation is balanced.Convert mass(g) or volume(L) to moles, if necessary.Set up mole ratios.Use mole ratios to calculate moles of desired substituent.Convert moles to mass or volume, if necessary.
5 Stoich problem Type #1 = 8 mol NH3 Ex 1: How many moles of NH3 can be produced when 4 moles of N2 is reacted with excess H2? N2 + 3H2 2NH3 4 mol N22 mol NH31 mol N2= 8 mol NH3
6 Ex 2: 2N2 + O2 2N2O How many moles of N2 must be reacted with excess O2 to produce 10 moles of N2O? 10 mol N2O2 mol N22 mol N2O= 10 mol N2
7 Grams of Given to Grams of Unkown Roadmap MEMORIZE!!! (Mole Ratio) g GIVEN mol GIVEN mol UnKnown g UNKNOWN mol GIVEN
8 Stoich Problem Type#2 116 g NaCl Ex 3: 46 grams of Sodium (Na) reacts with an excess Chlorine (Cl). How many grams of Sodium Chloride (NaCl) are formed?2Na Cl2 2NaCl46 g Na1 mol Na2 mol NaCl58 g NaCl=23 g Na2 mol Na1 mol NaCl116 g NaCl
9 Ex 4: How many grams of water can be prepared from 8 grams of hydrogen at standard conditions? 2 H2 (g) + O2(g) → 2 H2O8 g H21 mol H22 mol H2O18 g H2O2 g H21 mol H2O2 mol H2= 72 g H2O
10 Gas StoichiometryIf reactants and products are at the same conditions of temperature and pressure, then mole ratios of gases are also volume ratios.3 H2(g) N2(g) NH3(g)3 moles H mole N moles NH33 liters H liter N liters NH3
11 Gas Stoichiometry 3 H2(g) + N2(g) 2NH3(g) Ex 5: How many liters of NH3 can be produced when 12 liters of H2 react with an excess of nitrogen?3 H2(g) + N2(g) 2NH3(g)12 L H22L NH3= L NH38.03L H2
12 Ex 6: How many liters of oxygen are required to react completely with 22.4 liters of carbon monoxide, CO, at standard conditions? 2 CO (g) + O2(g) → 2 CO2 (g)22.4 L CO1L O2= L O211.22L CO