Transcript 2 mol NH 3 - Cloudfront.net

Chapter 9A Notes
Stoichiometry
West Valley High School
General Chemistry
Mr. Mata
1
Standard 3e
• Students will know how to
calculate the mole or mass of a
reactant or product from the
mole or mass of one of the
reactants or products.
2
Essential Question
• How is stoichiometry
used to relate
reactants & products
in a chemical reaction?
3
Stoichiometry
• Stoicheion = g. “element”
• Metron = g. “measure”
• Stoichiometry = “to measure the
elements”
• Stoichiometry - calculation of
quantities of substances involved
in chemical rxns.
• Use coefficients of balanced
chemical equations to show ratio
of moles of reactants & products: 4
Two Types of
Stoichiometry
• Composition stoichiometry – mass
relationships of elements in
compounds.
• Reaction stoichiometry – mass
relationships between reactants
and products in a chemical
reaction.
• Based on chemical equations and
the Law of Conservation of Mass
5
Steps to Stoichiometry
1. Start with a balanced chemical
equation.
2. Use number of moles of reactants
& products.
Two types of stoichiometry
problems:
1. Mole A -> mole B
2. Gram A -> mole A -> mole B ->
gram B
6
What does this equation
mean?
• N2
1 mole of
nitrogen (N2)
reacts with
+
3H2
3 moles of
hydrogen (H2)
to form:
2NH3
2 moles of
ammonia (NH3)
7
N2 +
3H2
2NH3
• Mole ratios:
1 mol N2
or
3 mol H2
1 mol N2
1 mol N2
or
2 mol NH3
3 mol H2
2 mol NH3
3 mol H2
or
2 mol NH3
1 mol N2
2 mol NH3
3 mol H2
8
Mole-Mole Calculations
• Steps:
• 1. Write the balanced chemical
equation.
• 2. Write moles of given
reactant/product.
• 3. Multiply by the mole ratio:
given mol A x mol B = ___ mol B
mol A
9
N2
+
3H2
2NH3
Calculate the moles of NH3 that can be
produced from 10.8 moles of H2.
3 mol H2 = 2 mol NH3 (mol : mol ratio)
10.8 mol H2 x 2 mol NH3 =
3 mol H2
= 7.2 mol NH3
10
N2
+
3H2
2NH3
Calculate the moles of NH3 that can
be produced from 25 moles of N2.
1 mol N2 = 2 mol NH3 (mol : mol ratio)
25 mol N2 x
2 mol NH3 =
1 mol N2
= 50 mol NH3
11
N2
+
3H2
2NH3
Calculate the moles of NH3 that can
be produced from 53.7 moles of H2.
3 mol H2 = 2 mol NH3 (mole : mole
ratio)
53.7 mol H2 x 2 mol NH3 =
3 mol H2
= 35.8 mol NH3
12
Mole: Mole Problem
• __ Al2O3 -> __ Al + __ O2
• Calculate the moles of Al that can be
produced from 20 moles of Al2O3.
__ mol Al = __ mol Al2O3 (mol : mol ratio)
___ mol Al2O3 x
mol Al
=
mol Al2O3
13
Solution:
• 2 Al2O3 -> 4 Al + 3 O2
• Calculate the moles of Al that can be
produced from 20 moles of Al2O3.
4 mol Al = 2 mol Al2O3 (mol : mol ratio)
20 mol Al2O3 x
• 40 mol Al
4 mol Al
2 mol Al2O3
=
14
Chapter 9A SUTW Prompt
• Describe the steps used to solve a
mole:mole stoichiometry problem.
• 1 RDF + 3 red examples (steps)
• Complete a 6 -8 sentence
paragraph using the SUTW
paragraph format. Hilight using
green, yellow, and pink.
• Due Date: Tomorrow (start of
class).
15