1 • Electrolytes • Molarity and Dilutions • Precipitation Reactions • Acid Base Reactions • Oxidation Reduction Reactions Big Idea: Reactions can be broken down into subgroups. Three types of reactions are precipitation (a solid is formed from 2 aqueous solutions), acid/base (salt and H 2 O are produced), and oxidation/reduction (e - are transferred). Many reactions involve species that are in solution. Molarity (mol per liter) is used to describe the concentration of species in a solution. Chapter 4 Types of Chemical Reactions and Solution Stoichiometry
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1
• Electrolytes
• Molarity and
Dilutions
• Precipitation
Reactions
• Acid Base
Reactions
• Oxidation
Reduction
Reactions
Big Idea: Reactions can be
broken down into
subgroups. Three types
of reactions are
precipitation (a solid is
formed from 2 aqueous
solutions), acid/base
(salt and H2O are
produced), and
oxidation/reduction (e-
are transferred). Many
reactions involve species
that are in solution.
Molarity (mol per liter) is
used to describe the
concentration of
species in a solution.
Chapter 4
Types of Chemical
Reactions and
Solution
Stoichiometry
Chapter 4: Types of Chemical Reactions and Solution Stoichiometry
Electrolytes
2
General Rule:
Polar Molecule: A molecule that has a partially
negative side and a partially positive side.
CO OH H
Chapter 4: Types of Chemical Reactions and Solution Stoichiometry
Electrolytes
3
Chapter 4: Types of Chemical Reactions and Solution Stoichiometry
Electrolytes
4
Solid
Dissolve Not Dissolve
Form Ions Stays Together as a Molecule
Chapter 4: Types of Chemical Reactions and Solution Stoichiometry
Electrolytes
Electrolyte: A substance that, in solution, is
present as ions.
Strong Electrolyte: A substance that is fully
ionized in solution.
Weak Electrolyte: A substance that is only
partially ionized in solution
Nonelectrolyte: A substance that does not form
ions in solution.
.5
Examples: Ionic solids that are soluble in water and acids.
Note: Electrolyte solutions conduct electricity.
Example: Molecular compounds that are not acids.
Chapter 4: Types of Chemical Reactions and Solution Stoichiometry
Student Question
Electrolytes
Which of the following is an nonelectrolyte?
a) NaCl
b) HC2H3O2
c) C12H22O11
d) Two of them are nonelectrolytes
e) All of them are nonelectrolytes
6
Chapter 4: Types of Chemical Reactions and Solution Stoichiometry
Take Away From Chapter 4 - Electrolytes
Electrolytes
Be able to identify electrolytes (ionic compounds and
acids)and nonelectrolytes (molecular compounds that are not
acids). (15,17)
7
Numbers correspond to end of chapter questions.
8
• Electrolytes
• Molarity and
Dilutions
• Precipitation
Reactions
• Acid Base
Reactions
• Oxidation
Reduction
Reactions
Big Idea: Reactions can be
broken down into
subgroups. Three types
of reactions are
precipitation (a solid is
formed from 2 aqueous
solutions), acid/base
(salt and H2O are
produced), and
oxidation/reduction (e-
are transferred). Many
reactions involve species
that are in solution.
Molarity (mol per liter) is
used to describe the
concentration of
species in a solution.
Chapter 4
Types of Chemical
Reactions and
Solution
Stoichiometry
Chapter 4: Types of Chemical Reactions and Solution Stoichiometry
Molarity and Dilutions
Solvent: The more abundant component of a
solution.
Solute: A dissolved substance.
Describing Solutions
Molarity M or c (units: 𝑚𝑜𝑙
𝐿or M)
𝑀 =𝑛
𝑉n = moles
V = volume of solution
9
Chapter 4: Types of Chemical Reactions and Solution Stoichiometry
Molarity and Dilutions
What is the molarity of 12.0 g of NaCl dissolved in
enough water to make 0.25 L of solution?
Molarity as a conversion factor
10
Chapter 4: Types of Chemical Reactions and Solution Stoichiometry
Molarity and Dilutions
11
Volume
Grams
Moles
Moles
Molar Mass
Atoms/Molecules/etc
NA
Chemical Formula
or EquationMolarity
Chapter 4: Types of Chemical Reactions and Solution Stoichiometry
Student Question
Molarity and Dilutions
If the molarity of a solution of calcium chloride
is known. What would you have to do to the
molarity of the calcium chloride solution to get
the molarity of the chloride ions in solution?
a) It is the same
b) Multiply the molarity by 2
c) Divide the molarity by 2
d) Multiply the molarity by 3
e) Not enough information given
12
Chapter 4: Types of Chemical Reactions and Solution Stoichiometry
Molarity and Dilutions
The steps to make a solution of known molarity.
1. A known mass of the solute is dispensed into a volumetric flask.
2. Some water is added to dissolve it.
3. Water is added up to the mark on the stem of the flask.
13
Chapter 4: Types of Chemical Reactions and Solution Stoichiometry
Molarity and Dilutions
Calculating Amount of Stock Solution Needed
Step 1: Calculate the amount of solute, n,
needed in the final solution, V2.
𝑛 = 𝑀2 𝑉2 Step 2: Calculate the volume, V1, of the initial
stock solution of molarity M1 that contains n
moles .
𝑉1 =𝑛
𝑀1
𝑉1 =𝑀
2𝑉2
𝑀1
or 𝑀1𝑉1 = 𝑀2𝑉2
14
Note: Since the amount of moles is the same in step 1 and 2, the equations can be
combined into one equation.
Chapter 4: Types of Chemical Reactions and Solution Stoichiometry
Molarity and Dilutions
Calculate the volume of 0.0155 M HCl that is
needed to prepare 0.100 L of 5.23x10-4 M HCl?
15
Chapter 4: Types of Chemical Reactions and Solution Stoichiometry
Student Question
Molarity and Dilutions
A solution is prepared by dissolving
0.005736 mol of oxalic acid (C2H2O4) to make
0.1000 L of solution. A 0.01000 L portion is then
diluted to 0.2500 L. What is the molarity of the
final solution?
a) 2.295×10-3 M
b) 2.295 M
c) 5.738×10-2 M
d) 5.737 M
e) None of the above
16
Chapter 4: Types of Chemical Reactions and Solution Stoichiometry
Take Away From Chapter 4 – Molarity and Dilutions
Molarity and Dilutions
Be able to calculate the molarity of a solution (13,21,26)
𝑀 =𝑛
𝑉
Be able to determine the molarity of solutions after
dilutions.(27,28,30)
𝑀1𝑉1 = 𝑀2𝑉2
17
Numbers correspond to end of chapter questions.
1
8
• Electrolytes
• Molarity and
Dilutions
• Precipitation
Reactions
• Acid Base
Reactions
• Oxidation
Reduction
Reactions
Big Idea: Reactions can be
broken down into
subgroups. Three types
of reactions are
precipitation (a solid is
formed from 2 aqueous
solutions), acid/base
(salt and H2O are
produced), and
oxidation/reduction (e-
are transferred). Many
reactions involve species
that are in solution.
Molarity (mol per liter) is
used to describe the
concentration of
species in a solution.
Chapter 4
Types of Chemical
Reactions and
Solution
Stoichiometry
Chapter 4: Types of Chemical Reactions and Solution Stoichiometry
Precipitation Reactions
Pb(NO3)2(aq) + 2KI(aq) PbI2 + 2KNO3
Top Solution Pb(NO3)2:
Bottom Solution KI:
Possible Ions in Solution:
Possible Solids in Solution:
19
Chapter 4: Types of Chemical Reactions and Solution Stoichiometry
Precipitation Reactions
Precipitate: The formation of a solid in a solution
during a chemical reaction.
Soluble Substance: A substance that dissolves to
a significant extent in a specified solvent.
Insoluble Substance: A substance that does not
dissolve significantly in a specified substance.
20
Note: If no solvent is mentioned, the solvent is assumed to be water.
Note: A substance is considered insoluble if they do not dissolve to more than
~0.1 M.
Chapter 4: Types of Chemical Reactions and Solution Stoichiometry
Precipitation Reactions
1. Most nitrate, NO3-, salts are soluble.
2. Most salts of Na+, K+, and NH4+ are soluble.
3. Most chlorides are soluble. Notable exceptions
are AgCl, PbCl2, and Hg2Cl2.
4. Most sulfate salts are soluble. Notable
exceptions are BaSO4, SrSO4, PbSO4, and
CaSO4.
5. Most hydroxide salts are only slightly soluble.
The important soluble hydroxides are NaOH,
KOH, and Ca(OH)2(marginally soluble).
6. Most sulfide (S2-), carbonate(CO32-), and
phosphate (PO43-) salts are only slightly soluble.
21
Chapter 4: Types of Chemical Reactions and Solution Stoichiometry
Precipitation Reactions
Are the following compounds soluble?
CaCl2
NH4NO3
Pb(OH)2
MgSO4
22
Chapter 4: Types of Chemical Reactions and Solution Stoichiometry
Student Question
Precipitation Reactions
How many of the following compounds are
soluble in water?
Ba3(PO4)2
Ba(NO3)2
K2CO3
Cu(OH)2
a) 1
b) 2
c) 3
d) 4
23
Chapter 4: Types of Chemical Reactions and Solution Stoichiometry
Precipitation Reactions
Step 1: Determine if a chemical reaction takes
place and write a balanced chemical reaction.
Step 2: Write the complete ionic equation (show
all ions separately).
Step 3: Determine the spectator ions (ions that
do not participate in the reaction).
Step 4: Write the net ionic equation (only species
that participate in the reaction).
24
Note: If no reaction takes place stop here.
Chapter 4: Types of Chemical Reactions and Solution Stoichiometry