CHEM 1001/CHM 1020/ Chm1025C/CHM1032C Name:_Answers_

Module 5 SamplePretest

Part I Mole-Mole Stoichiometry 5 points

 

Tungsten occurs in the important mineral sheelite (Calcium tungstate), which is converted to tungstic acid. Tungsten is then extracted from tundstic acid by the following (unbalanced) reaction:

3 H2 + H2WO4 W + 4 H2O

 

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

 

Question: ____?_____moles H2 = 6 moles W

 

 

 

Phosphoric acid can be made by the following (unbalanced) reaction:

 

6 H2O + P4O10 4 H3PO4

 

How many moles of Phosphoric acid can be prepared from the combination of 5 moles of Tetraphosphorus decoxide with excess water?

 

Question: ____?_____moles H3PO4 = 5 moles P4O10

 

 

Suggested Additional Homework Problems: p276 #7-12

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CHEM 1001/CHM 1020/ Chm1025C/CHM1032C Name:__Answers______

Module 5 SamplePretest

Module Five-Part J Mass-Mass Stoichiometry 5 points

 

1. Toluene and nitric acid are used in the production of trinitrotoluene (TNT), an explosive:

 

C7H8 + 3 HNO3 C7H5N3O6 + 3 H2O (Unbalanced)

 

Calculate the mass of TNT that can be made from excess C7H8 (toluene) with 126 grams of Nitric acid.

ANSWER:

 

Question: ____?____g C7H5N3O6 = 126 g HNO3

 

 

 

2. 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. Write and balance the equation for combustion.

ANSWER:

 

C3H8 + 5 O2 3 CO2 + 4 H2O

Question:

_____?_____g CO2 = 176g C3H8

 

 

Using ChemiCalc ANSWER:

 

Suggest Additional Homework Problems: p276 #19-28