Stoich Adjusting to reality Limiting and Excess Reactants

+ Stoich Adjusting to reality. Limiting and Excess Reactants

+ Limiting Reactant n Definition: The reactant that limits the amount of product made. n Think of the activity we did with the bread and peanut butter n Which one was the limiting reactant? (the one we ran out of) • Bread n Which one was the excess reactant? (the one we had extra of) • Peanut butter

+ Example 1: n Sodium chloride can be prepared by the reaction of sodium metal with chlorine gas: n 2 Na + Cl 2 2 Na. Cl Suppose that 6. 70 mol Na reacts with 3. 20 mol Cl 2. a. What is the limiting reactant? b. What is the excess reactant? c. How many moles of Na. Cl is produced?

+ Example 2: n The equation for the complete combustion of ethene (C 2 H 4) is : C 2 H 4 + 3 O 2 2 CO 2 + 2 H 2 O If 2. 70 mol C 2 H 4 is reacted with 6. 30 mol O 2 n What is the limiting reactant? n What is the excess reactant? n Calculate the moles of water produced.

+ Example 3: 2 Cu + S Cu 2 S n 80. 0 g of copper reacts with 25. 0 g of sulfur. a) What is the limiting reactant? b) What is the excess reactant? c) What is the maximum number of grams of Cu 2 S that can be formed?

+ Example 4: 2 KBr(aq) + Cl 2(aq) 2 KCl (aq) + Br 2(l) n When 0. 855 g of Cl 2 and 3. 205 g of KBr are mixed in solution: n A) What is the limiting reactant? n B) What is the excess reactant? n C) How many grams of Br 2 are formed?