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# Lecture 12.2a- Mol-Mol Stoich

## on Dec 04, 2009

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Section 12.2a lecture for Honors & Prep Chemistry

Section 12.2a lecture for Honors & Prep Chemistry

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• Manufacturing plants produce ammonia by combining nitrogen with hydrogen. Ammonia is used in cleaning products, fertilizers, and in the manufacture of other chemicals.

## Lecture 12.2a- Mol-Mol StoichPresentation Transcript

• Bellwork- Simple Stoich
• H 2 O 2 (aq)  H 2 O (l) + O 2 (g)
• 1. Balance the equation
• 2. How many moles of H 2 O 2 must decompose in order to get 2 moles of O 2 (g)?
• 3. How many liters of O 2 (g) are formed from the decomposition of 2 moles of H 2 O 2 at STP?
• 4. Which are conserved in this reaction- Atoms, molecules, volume, moles, mass?
• If given a quantity for one compound in a balanced equation you can calculate quantities for all of the others using stoichiometry .
• Example- 2 moles of N 2 requires ____moles of H 2 and will produce ____moles of NH 3.
• N 2 ( g ) + 3H 2 ( g )  2NH 3 ( g ) Reactant #1 Reactant #2 Product
6 4
• A mole ratio is a conversion factor made with the coefficients of a balanced chemical equation.
• N 2 ( g ) + 3H 2 ( g )  2NH 3 ( g )
• A mole ratio is a conversion factor made with the coefficients of a balanced chemical equation.
• N 2 ( g ) + 3H 2 ( g )  2NH 3 ( g )
• Some mole ratios:
• 1 mole N 2 3 moles H 2 1 mole N 2
• 3 moles H 2 1 mole N 2 2 mol NH 3
• N 2 ( g ) + 3H 2 ( g )  2NH 3 ( g )
Use a mole ratio to convert between two different compounds in a balanced equation!
• Some mole ratios:
• 1 mole N 2 3 moles H 2 1 mole N 2
• 3 moles H 2 1 mole N 2 2 mol NH 3
• STOICHIOMETRY
• You need a balanced equation.
• Convert the given quantity to moles if needed.
• Convert moles of given compound to moles of another compound by using the mole ratio from the balanced equation.
• Convert moles to grams if needed
N 2 + 3H 2  2NH 3 .6mol N 2 x ________ 1mol N 2 2mol NH 3 = 1.2mol NH 3 These numbers come from the balanced equation
• for Sample Problem 12.2
• For Stoichiometry–
• You ALWAYS use moles!!
• If you are not given moles you must convert to moles.
• Use the mole ratio to convert between compounds.
• 1. How many moles of water are produced when 2.5 mol of O 2 react according to the following equation?
• C 3 H 8 + 5O 2  3CO 2 + 4H 2 O
• 2.0
• 2.5
• 3.0
• 4.0