CHM 1020 Path 4 Chapter 9 Study Pack Part III

Chapter 9 Part III: Chemical Equations & Stoichiometry (Chapter 9)

Chapter 9 Part F  Chapter 9   Part F  Mole-Mole Stoichiometry  Homework #1: Tungsten occurs in the important mineral sheelite (Calcium tungstate), which is converted to tungstic acid.  Tungsten is then extracted from tungstic acid by the following (unbalanced) reaction:

H2   +       H2WO4      à        W        +        H2O

How moles of hydrogen is needed to prepare 6 moles of elemental tungsten?

Homework #2: Phosphoric acid can be made by the following (unbalanced) reacti

H2O               +             P4O10     à              H3PO4

How many moles of Phosphoric acid can be prepared from the combination of 5 moles of Tetraphosphorus decoxide with excess water? Part F2  Mass-Mass Stoichiometry

Use this concept map for Part F2 Mass-Mass Problems:   The Solution to:   __?____gHg = 1.25g 1.25 gHgO     Homework #3: Toluene and nitric acid are used in the production of trinitrotoluene (TNT), an explosive:

C7H8      +   HNO3       à      C7H5N3O6      +     H2O      (Unbalanced)

Calculate the mass of TNT that can be made from 192 g of C7H8 (toluene).

Homework #4: What mass of carbon dioxide is produced from the combustion of 176 grams of propane gas ,  C3H8 , in excess oxygen gas,  O2.  Water is the only other product.

Part F3 Excess-Limiting Reagent Problem Sample Limiting Reagent Problem   Some books teach you to determine which reagent is the limit first, then do the standard gram-gram problem. The following is an example of this method.

Either works, but I prefer the  method above.  Homework #5: How many grams of Calcium phosphate can be made according to the reaction (unbalanced):

CaCl2       +     K3PO4     ---->        Ca3(PO4)2        +   KCl

by mixing a solution of 5.00 grams of CaCl2   with another containing 8.00 grams of Potassium phosphate?

Part F3 Impure Reagents/Percent Yield Problem   Homework #6:  A laboratory manual calls for 13.0 grams of butanol reactant in excess sodium bromide and sulfuric acid as reactants in this reaction:

C4H9OH   +   NaBr     +     H2SO4   ------>     C4H9Br   +   NaHSO4    +   H2O

A student following these directions obtains 16.8 grams of butyl bromide (C4H9Br).   What is the theoretical yield and the percent yield of this reaction?