View
218
Download
2
Category
Preview:
Citation preview
BRN
Complete the table using the balanced chemical reaction:
______CH4 + ______O2 _____CO2 + _____H2O
Molecules CH4
Molecules O2
→Molecules
CO2
Molecules H2O
4.0 →
→ 5.0
Stoichiometry Notes
New Section in Table of Contents
Real Life Application
Ingredients
2 1/4 cups all-purpose flour
1 teaspoon baking soda
1 teaspoon salt
1 cup (2 sticks) butter, softened
3/4 cup granulated sugar
3/4 cup packed brown sugar
1 teaspoon vanilla extract
2 large eggs
2 cups (12-oz. pkg.) NESTLÉ® TOLL HOUSE® Semi-Sweet Chocolate Morsels
1 cup chopped nuts
Real Life Application
We cannot forget about the law of conservation of mass.
The mass of what we put in must be equal to what we get out.
KC 1: The excess reactants are all the leftover unused reactants. (The reactant that’s leftover).
Particle and Mole Relationships
Chemical reactions stop when one of the reactants is used up
KC 2: Stoichiometry is the study of quantitative relationships between the amounts of reactants used and amounts of products formed by a chemical reaction
So based on how much reactant you put in you can calculate how much product you will get out
Particle and Mole Relationships
Particle and Mole Relationships
KC 3: A mole ratio is a ratio between the numbers of moles of any 2 substances in a balanced equation
This can only be determined from a balanced chemical equation
Particle and Mole Relationships
Let practice: What is the mole-to-mole ratio for… 10C2H4O + 15O2 20CO2 + 2H2O
CH4 + 2O2 CO2 + 2H2O
H2 + O2 H2O
Using Stoichiometry
CH4 + 2O2 CO2 + 2H2O
Mol CH4 Mole H2O
Using Stoichiometry
Key Concept 4:
How many moles of SO3 are formed if you start with 5.25 moles of Sulfur and have excess Oxygen?
____S + ____O2 ____SO3
Using Stoichiometry
Key Concept 5:
How many moles of SO3 are formed if you start with 0.25 moles of oxygen and have excess sulfur?
____S + ____O2 ____SO3
Using Stoichiometry
Key Concept 6:
How many moles of water are formed if you start with 0.345 moles of CH4?
______CH4 + ______O2 → _____CO2 + _____H2O
Lab Introduction
Make your own soda!
Using Stoichiometry How many grams of Fe2O3 are formed when 12.37g
of iron reacts with excess oxygen using the balanced chemical equation below:
4Fe(s) + 3O2(g) 2Fe2O3(s)
Using Stoichiometry
4Fe(s) + 3O2(g) 2Fe2O3(s)
12.37g Fe
Mol Fe Mole Fe2O3
?? g Fe2O3
Using StoichiometryKey Concept 7:
How many grams of lithium nitrate will be needed to make 250.0 grams of lithium sulfate, assuming that you have an adequate amount of lead (IV) sulfate to do the reaction?
____Pb(SO4)2 + ____LiNO3 ____Pb(NO3)4 + ____Li2SO4
Using StoichiometryKey Concept 8:
How many grams of sodium sulfate will be formed if you start with 20.0 grams of sodium hydroxide and you have an excess of sulfuric acid?
____NaOH + ____H2SO4 ____H2O + ____Na2SO4
Using StoichiometryKey Concept 9:
How many grams of water will be formed if you start with 200.0 grams of sodium hydroxide and you have an excess of sulfuric acid?
____NaOH + ____H2SO4 ____H2O + ____Na2SO4
Practice
How many grams of CaCl2 are formed when 21.3g of Ca(OH)2 reacts with excess HCl?
_____Ca(OH)2 + _____HCl ______CaCl2 + ______H2O
Practice How many grams of BaCl2 are formed from
6.0 moles of Ba(ClO3)2?
_______Ba(ClO3)2 → _______BaCl2 + _____O2
Practice Iron(III) oxide, Fe2O3, can be reduced to iron by
passing carbon monoxide, CO, over the heated oxide. How many moles of iron can be produced from 1.234 moles of Fe2O3 oxide and excess carbon monoxide?
______Fe2O3(s) + _____CO(g) _____Fe(s) + _____CO2(g)
Practice Butyne, C4H6, burns in the presence of oxygen in air
to produce carbon dioxide, CO2, and water H2O. How many moles of oxygen will be required to produce 45.99 moles of carbon dioxide?
______C4H6 + ______O2 ______CO2 + ______H2O
Practice The following reaction can be used to remove CO2
breathed out by astronauts in a spacecraft.
2 LiOH + 1 CO2 → 1 Li2CO3 + 1 H2O
a. How many grams of carbon dioxide can be removed by 5.5mol LiOH?
b. How many grams of water could be produced from 2.23g of LiOH?
Practice Calcium carbide, CaC2, reacts with water to form
acetylene.
1 CaC2 + 2 H2O → 1 C2H2 + 1 Ca(OH)2
a. How many grams of water (H2O) are needed to react with 485g of CaC2?
b. How many grams of CaC2 could make 23.6g C2H2?
Practice Oxygen can be prepared by heating potassium
chlorate:
2 KClO3 → 2 KCl + 3 O2
a. What mass of O2 can be made from heating 125g of KClO3?
b. How many grams of KCl could form from 20.8g KClO3?
BRN
Complete the table using: N2 + 3H2 → 2NH3
Moles N2 Moles H2 →Moles NH3
Excess N2 Excess H2
1.5 4.0 →
→ 4.0 2 0
Limiting and Excess Reactants
KC 10: If you have 2 givens in your problem, it is a limiting reactant problem
KC 11: The reactant that produces the smallest amount of a product is the limiting reactant. This is the reactant that will be used up first in the reaction.
Example How many grams of Cu can be formed when
167.4 g of Fe reacts with 399.2 g of CuCl2?
2 Fe + 3 CuCl2 3 Cu + 2FeCl3
Steps for solving LR problems
KC 12:
1. Write down the givens
2. Use molar mass to convert to moles
3. Use mole ratio from the balanced equation
4. Convert to desired unit
5. The correct answer is the smallest answer as the reaction will stop once one reactant is gone
Limiting and Excess Reactant KC 13: 80.0g Cu reacts with 25.0g S. Determine which is
the limiting reactant and calculate how much Cu2S is formed in grams?
2Cu(s) + S(s) → Cu2S(s)
KC 14: What is the limiting reactant if 65.0g of each reactant is present?
___Zn + ___HCl → ___ZnCl2 + ___H2
Limiting and Excess Reactant
Excess and Percent Yield
KC 15: To find how much excess you have you must take the limiting reactant and solve for the excess reactant. You need to look at what you are given versus what you need.
Excess Reactant - Example
How many grams of Cu can be formed when 167.4 g of Fe reacts with 399.2 g of CuCl2?
2 Fe + 3 CuCl2 3 Cu + 2FeCl3
CuCl2 – limiting reactant
188.5g Cu is formed
How many grams of excess is left over?
Excess Reactant KC 16: 24.5g of barium chloride reacts with 45.2g of
sodium sulfate. Which is the limiting reactant and how much of the excess reactant is left over at the end of the reaction?
___BaCl2 + ___Na2SO4 ___BaSO4 + ___NaCl
Percent Yield
KC 17: % yield = actual yield x 100
theoretical yield
KC 18: Actual yield must be found experimentally. It is recognized by words like “produced” and “formed”
KC 19: Theoretical yield is done using stoichiometry. It is a prediction and will always be done using math.
Percent Yield KC 20: A student calculated she should obtain 28g of a
substance. In the experiment, 25g was produced. What is the percent yield of the experiment?
Percent Yield - Example 167.4 g of Fe reacts with 399.2 g of CuCl2 to form
170.3g of copper. What is the percent yield of copper?
2 Fe + 3 CuCl2 3 Cu + 2FeCl3
Practice KC 21: 11.2g of nickel (II) sulfide reacts with 5.43g of
oxygen producing 4.97g of nickel (II) oxide. What is the percent yield of this reaction?
_____NiS2 + _____O2 → _____NiO + _____SO2
Practice KC 22: You are given 0.45g of Al(OH)3 and 0.55g of
H2SO4. The reaction produces 0.15g of water. What is the percent yield of this reaction?
____Al(OH)3 + _____H2SO4 → _____Al2(SO4)3 + _____H2O
Practice KC 23: You are given 3 moles of lithium and 3 moles of
nitrogen. The reaction produces .5 moles of lithium nitride. What is the percent yield of this reaction?
____Li + _____N2 → _____Li3N
Recommended