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Gas Laws and Stoichiometry

Stoichiometry: Mass-Mass and Mole-Mole

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Stoichiometry: Mass-Mass and Mole-Mole
Stoichiometry: Volume-Volume and Limiting Reagents
Gas Laws: Boyle's Law and Charles' Law
Gas Laws: Combined Gas Law and Ideal Gas Law

Mass-Mass

2KCIO3 ----> 2KCl + 3O2
 
How many grams of potassium chloride are produced if 25g of potassium chlorate decompose?
 
So you are trying to find grams of KCl. So start off with the given (25g) and do dimensional analysis to get grams of KCl. So go from 25g of KCIO to the molar mass, which is 122 grams, which gives you 1 mole of KCIO. For every 2 moles of KCIO (the coefficient "2" in front of KCIO is the # of moles), there are 2 moles of KCl. So then find the molar mass of 1 mole KCl, ( 74g), and multiply it out! See if you got the right answer (see Mass-Mass Problem 1 Picture)

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Mole-Mole
 
Zn + 2HCl ----> ZnCl2 + H2
 
How many moles of hydrogen are produced from the reaction of three moles of zinc with an excess of hydrochloric acid?
 
The mole-mole problems are short and sweet. You start off with the given again ( 3 moles of Zn). Since you are trying to find moles of H2, you go from moles of Zn to moles of H2. So for every 1 mole of Zn, you have 1 mole of H2. Now just multiply it out!

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Backpacker taking a drink; Size=180 pixels wide
Practice Problems

More Problems:
Mass-Mass
1. N2 + 3H2 ---> 2NH3  How many grams of hydrogen are necessary to react completely with 50 g of nitrogen?
 
2. 2AgNO3 = BaCl2 ---> 2AgCl + Ba(NO3)2  How many grams of silver chloride are produced from 5 g of silver nitrate reacting with an excess of barium chloride?
 
Mole-Mole
 
1. N2 + 3H2 --->  2NH3  How many moles of hydrogen are needed to completely react with two moles of nitrogen?
 
2. C3H8 + 5O2 ----> 3CO2 + 4H2O How many moles of oxygen are necessary to react completely with four moles of propane (C3H8) ?

Answers:
Mass-Mass
1.  10.7 g H2
2. 4.2 g Ag
Mole-Mole
1. 6 moles of H2
2. 20 moles of O2