What does STOICHIOMETRY mean?
（”stochio”= Greek for element; “metry”= measurement）
Stoichiometry = measuring the amounts of elements and compounds involved in a chemical reaction = relationship between the amount of reactants and products
Consider the equation: 2Mg + O2 --> 2MgO
Mole Ratio of the above equation = 2: 1: 2
(2 moles of Mg react with 1 mole of O2 to produce 2 moles of MgO.)
- It tells us the ration of the molecules in an equation
- The ratio can also be used as conversion factors
(What you need over what you have OR Where you’re going over where you start.)
Conversion
Ex. Write the molar ratios for N2 to H2 and NH3 to H2.
N2 + 3 H2 --> 2 NH3
- N2 to H2: 3/1
- NH3 to H2: 2/3
Ex. How many moles of O2 will be formed when 5.1 moles of H2O is decomposed?
2 H2O --> 2 H2 + O2
- 5.1 mole H2O×1mole O2 / 2 moles H2O = 2.6 moles O2
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