GAS STOICHIOMETRY (p. 440 – 443 in text book)

* chemical reaction is happening
* deals with two different substances (at least 1 is a gas)
* given chemical equation
* assume reaction occurs at STP unless otherwise noted
--------------------------------------------------------------

STOICHIOMETRY STEPS
~ Balance the equation
~ Write the important information from the problem

1st addition to “train tracks”:  use molar mass of given substance (if given a # of grams)      or
                                           use 22.4 L = 1 mole of gas @ STP (if given liters)

2nd addition to “train tracks”:  use coefficients in the mole ratio

3rd addition to “train tracks”:  use molar mass of unknown substance (if problem asks for grams)                  or
                                            use 22.4 L = 1 mole of gas @ STP (if problem asks for liters)            

Example # 1
How many Liters of carbon dioxide gas can be produced from the decomposition of 4.50 grams of sodium carbonate?
                                    Na2CO3 
à    Na2O  +    CO2
4.50 g Na2CO3 | 1 mole Na2CO3 |    1 mole CO2   | 22.4 L CO2 = 0.951 L CO2
                     
| 106 g Na2CO3   | 1 mole Na2CO3 | 1 mole CO2

Example # 2
How many grams of aluminum are needed to completely react with 16.0 L of oxygen?
    Al  +    O2 
à    Al2O3                                            (Ans:  25.7 g)

 

Back to the Unit 10 Notes Page

Back to the Unit 10 Page

Back to the Main Page