Major points*A balanced equation relates the numbers of molecules of reactants and products. It can also be expressed in terms of the numbers of moles of reactants and products.
*The process of using a chemical equation to calculate the relative amounts of reactants and products involved in the reaction is called doing stoichiometric calculations. To convert between moles of reactants and moles of products, we use mole ratios derived from the balanced equation. *Often reactants are not mixed in stoichiometric quantities (they do not "run out" at the same time). In that case, we must use the limiting reactant to calculate the amount of products formed. *The actual yield of reaction is usually less than its theoretical yield. Th actual yield is often expressed as a percentage of the theoretical yield, which is called percent yield. Videosstoichiometry:http://www.youtube.com/watch?v=80a47D1x5Hs
percent yield: http://www.youtube.com/watch?v=mmsKDK9WXdE ActivityStoichiometry Worksheet:
http://academic.evergreen.edu/curricular/matterandmotion/chem_phys%5Cpractice_problems.htm |
Online ResourcesStoichiometry:http://cnx.org/content/m15086/latest/
Moles in Stoichiometry: http://cnx.org/content/m14093/latest/ Example Problems1. Given the following equation: 2 KClO3 ---> 2 KCl + 3 O2
How many moles of O2 can be produced by letting 12.00 moles of KClO3 react? 18.00 moles 2. Given the following equation: 2 K + Cl2 ---> 2 KCl How many grams of KCl is produced from 2.50 g of K and excess Cl2. From 1.00 g of Cl2 and excess K? 4.77 g of KCl/ 2.10 g of KCl 3. Given the following equation: Na2O + H2O ---> 2 NaOH How many grams of NaOH is produced from 1.20 x 102 grams of Na2O? How many grams of Na2O are required to produce 1.60 x 102 grams of NaOH? 155 g of NaOH/ 124 g of Na2O 4. Given the following equation: 8 Fe + S8 ---> 8 FeS What mass of iron is needed to react with 16.0 grams of sulfur? How many grams of FeS are produced? 27.9 g of Fe/ 43.9 g of FeS 5. Given the following equation: 2 NaClO3 ---> 2 NaCl + 3 O2 12.00 moles of NaClO3 will produce how many grams of O2? How many grams of NaCl are produced when 80.0 grams of O2 are produced? 576.0 g of O2/ 97.4 g of NaCl 6. Given the following equation: Cu + 2 AgNO3 ---> Cu(NO3)2 + 2 Ag How many moles of Cu are needed to react with 3.50 moles of AgNO3? If 89.5 grams of Ag were produced, how many grams of Cu reacted? 1.75 mol of Cu/ 16.4 g of Cu 7. Molten iron and carbon monoxide are produced in a blast furnace by the reaction of iron(III) oxide and coke (pure carbon). If 25.0 kilograms of pure Fe2O3 is used, how many kilograms of iron can be produced? The reaction is: Fe2O3 + 3 C ---> 2 Fe + 3 CO 17.5 kg 8. The average human requires 120.0 grams of glucose (C6H12O6) per day. How many grams of CO2 (in the photosynthesis reaction) are required for this amount of glucose? The photosynthetic reaction is: 6 CO2 + 6 H2O ---> C6H12O6 + 6 O2 175.9 g of CO2 |