Chapter 4 Types of Chemical Reactions and Solution Stoichiometry 1 PDF

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CHEMISTRY 120/121

Chapter 4 Types of Chemical Reactions and Solution Stoichiometry

Overview: 

Solution Stoichiometry



Electrolytes



Solubility of Ionic Compounds



Precipitation Reactions



Molecular, Ionic and Net Ionic Equations

Types of Chemical Reactions and Solution Stoichiometry Ch 4.1-4.6

Homogeneous mixtures are called ____________________. The component of the solution that changes state is called the ____________________. The component that keeps its state is called the ____________________. Note: If both components start in the same state, the major component is the ____________________. Since solutions are mixtures, the composition can vary from one sample to another. So to describe solutions accurately, we must describe how much of each component is present. We can describe a solution qualitatively or quantitatively. Qualitatively, solutions are often described as ____________________ or concentrated. 

Dilute solutions have a ____________________ amount of solute compared to solvent.



Concentrated solutions have a ____________________ amount of solute compared to solvent. 1 J. Zhou Summer 2018

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Chapter 4 Types of Chemical Reactions and Solution Stoichiometry

We use concentration in quantitatively describing a solution:

A common way to express a solution is using molarity:

Example: What is the molarity of a solution containing 3.4 g of NH3 (MM = 17.03 g/mol) in 200.0 mL of solution?

Example: Determine the mass of CaCl2 (MM = 110.98 g/mol) in 1.75 L of 1.50 M solution.

Example: How would you prepare 250.0 mL of 0.150 M CaCl2 (MM =110.98 g/mol)?

Often, solutions are stored as concentrated stock solutions. To make solutions of lower concentrations from these stock solutions, more ____________________ is added. This process is called a ____________________. Note: The amount of solute doesn’t change, just the volume of solution. 2 J. Zhou Summer 2018

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Chapter 4 Types of Chemical Reactions and Solution Stoichiometry

Example: What is the concentration of a solution prepared by diluting 45.0 mL of 8.25 M HNO3 to 135.0 mL?

Since molarity relates the moles of solute to the liters of solution, it can be used to convert between amount of reactants and/or products in a chemical reaction.

Example: 43.8 mL of 0.107 M HCl is needed to neutralize 37.6 mL of Ba(OH)2 solution. What is the molarity of the base? HCl

+ Ba(OH)2

→

BaCl2

+ H 2O

Ionic compounds dissociate ____________________ in an aqueous solution. Molecular compounds do ____________________ dissociate in an aqueous solution. 

Materials that dissolve in water to form a solution that will conduct electricity are called ____________________.



Materials that dissolve in water to form a solution that will not conduct electricity are called ____________________.

In order to conduct electricity, a material must have ____________________ particles that are able to flow. Electrolyte solutions all contain ____________________ dissolved in the water. Nonelectrolyte solutions contain whole molecules dissolved in the water. Generally, molecular compounds do not ionize when they dissolve in water.

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Chapter 4 Types of Chemical Reactions and Solution Stoichiometry

When an ionic compound dissolves in water, the ions are dispersed and are assumed to move around independently. Water can also dissolve non-ionic substances (e.g. ethanol is very soluble in water)

When compounds containing polyatomic ions dissociate, the polyatomic group stays together as one ion.

When a strong acid dissolves in water, the molecule ____________________ into H+ and anions.

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Chapter 4 Types of Chemical Reactions and Solution Stoichiometry

Acids are molecular compounds that ionize when they dissolve in water. 

The molecules are pulled apart by their attraction for the water.



When acids ionize, they form H+ cations and anions.

The percentage of molecules that ionize varies from one acid to another. Acids that ionize virtually 100% are called ____________________ acids.

Acids that only ionize a small percentage are called ____________________ acids.

Solubility of Ionic Compounds Some ionic compounds, like NaCl, dissolve very well in water at room temperature. Other ionic compounds, like AgCl, dissolve hardly at all in water at room temperature. Compounds that dissolve in a solvent are said to be ____________________, while those that do not are said to be ____________________. Note: The degree of solubility depends on the temperature. 5 J. Zhou Summer 2018

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Chapter 4 Types of Chemical Reactions and Solution Stoichiometry

The best way to predicting whether a compound will dissolve in water is to do some experiments to test whether a compound will dissolve in water, then develop some rules based on those experimental results. The result of many experiments provides us with a ____________________ table.

Example: Determine if each of the following is soluble in water. a) KOH b) AgBr c) CaCl2 d) Pb(NO3)2 e) Lead (II) Sulfate

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Types of Reactions There are many types of chemical reactions. Reactions between aqueous solutions of ionic compounds that produce an ionic compound that is insoluble in water are called ____________________ reactions, and the insoluble product is called a ____________________. We can use the solubility table to determine whether a product is soluble or insoluble in the aqueous environment. e.g. 2 KCl (aq) + Pb(NO3)2 (aq) →

To determine the products of a precipitation reaction: 1) Determine what ions each aqueous reactant has.

2) Determine formulas of possible products. 

Exchange ions: (+) ion from one reactant with (-) ion from other



Balance charges of combined ions to get formula of each product

3) Determine solubility of each product in water. 

Use the solubility rules



If product is insoluble or slightly insoluble, it will precipitate

4) If neither product will precipitate, write no reaction after the arrow.

5) If either product is insoluble, write the formulas for the products after the arrow—writing (s) after the product that is insoluble and will precipitate, and (aq) after products that are soluble and will not precipitate.

6) Balance the equation. 7 J. Zhou Summer 2018

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Example: Predict the products and balance the equation: a) KCl (aq) + AgNO3 (aq) →

b) Na2S (aq) + CaCl2 (aq) →

Equations that describe the chemicals put into the water and the product molecules are called ____________________ equations. 2 KOH (aq) + Mg(NO3)2 (aq) → 2 KNO3 (aq) + Mg(OH)2 (s)

Equations that describe the actual dissolved species are called ____________________ ____________________ ____________________ equations. 

Aqueous strong electrolytes are written as ions. o Soluble salts, strong acids, strong bases



Insoluble substances, weak electrolytes, and nonelectrolytes are written in molecule form. o Solids, liquids, and gases are not dissolved, therefore, molecule form

Ions that are both reactants and products are called ____________________ ions. An ionic equation in which the spectator ions are moved is called a ____________________ ____________________ equation.

Example: Write the net ionic equation for each. a) K2SO4 (aq)

+ AgNO3 (aq)

b) Na2CO3 (aq) + HCl (aq)

→

→

KNO3 (aq)

NaCl (aq)

+ Ag2SO4 (s)

+ CO2 (g)

+ H2O (l)

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