Stoichiometry with a Twist Given the density of oxygen is 1.439 grams per liter, how many liters of oxygen gas can be produced if 15.0g of mercury (II) oxide are heated to produce mercury and oxygen gas? 2HgO  2Hg +O2 ? L O2 = 15.0g HgO 1 mol HgO 1 mol O2 32g O2 1 L O2 217g HgO 2 mol HgO 1 mol O2 1.439g O2 = 0.770 L O2 Episode 803

Stoichiometry Problem Guidelines Balance the equation Convert to moles of given substance MAKE THE SWITCH USING THE MOLE RATIO FROM THE BALANCED EQUATION Convert to desired unit

Problem Set 1 8 5 6 C5H12 + O2  CO2 + H2O = 131 L CO2 Given that the density of carbon dioxide is approximately 1.99 g/L, what volume, in liters, of carbon dioxide will be produced if 85.0g of pentane are burned? How many molecules of water will be produced if 26.3g of pentane are burned? ? L CO2 = 85.0g C5H12 1 molC5H12 5 molCO2 44gCO2 1 L CO2 72gC5H12 1 molC5H12 1 molCO2 1.99gCO2 = 131 L CO2 ? molc H2O = 26.3g C5H12 1 molC5H12 6 molH2O 6.02 x 1023 molc H2O 72gC5H12 1 molC5H12 1 molH2O = 1.32 x 1024 molecules H2O

Limiting Reactant Excess Reactant Reactant used up first in a chemical reaction Produces the smallest amount of product Excess Reactant Reactant that is not used up in a chemical reaction Leftover when the reaction is complete

What is the limiting reactant? FeCl3 When FeCl3 reacts with O2, Fe2O3 and Cl2 are produced. If 4.0 moles of FeCl3 and 4.0 moles of O2 are mixed, how many grams of Fe2O3 will be produced? 4FeCl3 + 3O2  2Fe2O3 + 6Cl2 (Hint: Work two separate problems, using one reactant at a time.) ? g Fe2O3 = 4.0mol FeCl3 2mol Fe2O3 160g Fe2O3 = 320g Fe2O3 4.0mol FeCl3 1mol Fe2O3 ? g Fe2O3 = 4.0mol O2 2mol Fe2O3 160g Fe2O3 = 430g Fe2O3 3mol O2 1mol Fe2O3 (Hint: Answer will be the SMALLER amount of product.) What is the limiting reactant? FeCl3 What is the excess reactant? O2

What is the limiting reactant? Fe2O3 Iron(III) oxide reacts with carbon monoxide to form molten iron and carbon dioxide. If 0.18g of iron(III) oxide and 0.11g of carbon monoxide, how many grams of iron are produced? Fe2O3 + 3CO  2Fe + 3CO2 (Hint: Work two separate problems, using one reactant at a time.) (Hint: Answer will be the SMALLER amount of product.) ? g Fe = 0.18g Fe2O3 1mol Fe2O3 2mol Fe 56g Fe = 0.13g Fe 160g Fe2O3 1mol Fe2O3 1mol Fe ? g Fe = 0.11g CO 1mol CO 2mol Fe 56g Fe = 0.15g Fe 28g CO 3mol CO 1mol Fe What is the limiting reactant? Fe2O3 What is the excess reactant? CO