 Stoichiometry:

Objectives:

1.    Define stiochiometry and describe its significance.

2.    Explain the relationship between stoichiometry and balanced chemical equations.

Web Resources: (sphs.spusd.net/groves/ images/dert.gif)

Stoichiometry:

Stoichiometry is simply the measurement of reactants and products in a balanced equation.  As was stated earlier in this semester, mass is conserved in any balanced equation.  Therefore, we should be able to predict the quantity and mass of products from known reactants in any equation using stiochiometric relationships.

Interpreting balanced equations:    Mole - Mole Conversions

CH4 + 2O2  g  CO2 + 2H2O

Consider the balanced equation above.

Reactants: 1 mole of CH4 - contains 1 mole Carbon and 4 moles Hydrogen reacts with 2 moles of O2 - contains 4 moles Oxygen

Products: 1 mole CO2 - contains 1 mole Carbon and 2 moles Oxygen and 2 moles of H2O - contains 4 moles Hydrogen and 2 mole Oxygen

Stoichiometry is just like reading a recipe and should be approached the same way.  The above recipe calls for 1 part methane to be mixed with 2 parts oxygen to produce 1 part carbon dioxide and 2 parts water. 1 Egg + 1cup Bisquick + 0.5 cups Milk  =  8 Pancakes

How moles of methane would you mix with 10 moles O?  (remember that the mole ratio is 2:1)

A. 2.5    B.  5     C.  10    D.  20    (answer is at the bottom)

Math solution:    10 mol O x 1mol CH4 / 4 mol O = ?

How many moles of CO2 would this produce?

A. 2.5    B.  5     C.  10    D.  20    (answer is at the bottom)

Math solution:    10 mol O x 1mol CO2 / 4 mol O = ?

How many moles of H2O would this produce?

A. 2.5    B.  5     C.  10    D.  20    (answer is at the bottom)

Math solution:    10 mol O x 2mol H2O / 4 mol O = ?

How would the problem be different if you started with 10 moles O2?

answers: A, A, B, all quantities would be doubled.