Unit 4 (Ch. 8) Chemical Reactions

Predicting Decomposition Reactions (Notepack, pg. 4)

8.2 Types of ReactionsDECOMBINATION REACTIONSDECOMBINATION REACTIONS

A. Define decomposition reaction:

A single compound is broken down into two or more products.

Most compounds are broken down when energy is added (often in the form of heat or electricity)

8.2 Types of ReactionsDECOMBINATION REACTIONSDECOMBINATION REACTIONS

B. Write a general formula for a decomposition reaction:

AB A + B

8.2 Types of ReactionsDECOMBINATION REACTIONSDECOMBINATION REACTIONS

There are 5 Helpful Hints for Decomposition Reactions (Notepack pg. 5)

8.2 Types of ReactionsDECOMBINATION REACTIONSDECOMBINATION REACTIONS

1. Some oxy-acids, when heated, decompose to form water and the nonmetal oxide.

Oxy-acids are acids with oxygen in them:

H3PO4

HNO3 (NOT: HCl, HBr, etc)

8.2 Types of ReactionsDECOMBINATION REACTIONSDECOMBINATION REACTIONS

1. Some oxy-acids, when heated, decompose to form water and the nonmetal oxide.

A nonmetal oxide is just that, a nonmetal bonded with oxygen.

Examples: P2O3, N2O5, SO3, etc

8.2 Types of ReactionsDECOMBINATION REACTIONSDECOMBINATION REACTIONS

1. Some oxy-acids, when heated, decompose to form water and the nonmetal oxide.

Example: Sulfuric acid is heated

8.2 Types of ReactionsDECOMBINATION REACTIONSDECOMBINATION REACTIONS

1. Some oxy-acids, when heated, decompose to form water and the nonmetal oxide.

Example: Sulfuric acid is heated

H2SO4 + Oxy-acid water + nonmetal oxide

8.2 Types of ReactionsDECOMBINATION REACTIONSDECOMBINATION REACTIONS

1. Some oxy-acids, when heated, decompose to form water and the nonmetal oxide.

Example: Sulfuric acid is heated

H2SO4 H2O + ____

After transferring the H2O over, from the left to the right, what is left?

8.2 Types of ReactionsDECOMBINATION REACTIONSDECOMBINATION REACTIONS

1. Some oxy-acids, when heated, decompose to form water and the nonmetal oxide.

Example: Sulfuric acid is heated

H2SO4 H2O + SO3 Oxy-acid water + nonmetal oxide

8.2 Types of ReactionsDECOMBINATION REACTIONSDECOMBINATION REACTIONS

1. Some oxy-acids, when heated, decompose to form water and the nonmetal oxide.

Example: Nitric acid is heated

8.2 Types of ReactionsDECOMBINATION REACTIONSDECOMBINATION REACTIONS

1. Some oxy-acids, when heated, decompose to form water and the nonmetal oxide.

Example: Nitric acid is heated

HNO3 Oxy-acid water + nonmetal oxide

8.2 Types of ReactionsDECOMBINATION REACTIONSDECOMBINATION REACTIONS

1. Some oxy-acids, when heated, decompose to form water and the nonmetal oxide.

Example: Nitric acid is heated

HNO3 H2O + _____Oxy-acid water + nonmetal oxide

After transferring the H2O over, what is left?

8.2 Types of ReactionsDECOMBINATION REACTIONSDECOMBINATION REACTIONS

1. Some oxy-acids, when heated, decompose to form water and the nonmetal oxide.

Example: Nitric acid is heated

HNO3 H2O + NOOxy-acid water + nonmetal oxide

8.2 Types of ReactionsDECOMBINATION REACTIONSDECOMBINATION REACTIONS

2. Some metallic hydroxides (bases), when heated, decompose to form the metal oxide and water.

8.2 Types of ReactionsDECOMBINATION REACTIONSDECOMBINATION REACTIONS

2. Some metallic hydroxides (bases), when heated, decompose to form the metal oxide and water.

Metallic hydroxides include:

Ca(OH)2 calcium hydroxide

Mg(OH)2 magnesium hydroxide

NaOH sodium hydroxide

8.2 Types of ReactionsDECOMBINATION REACTIONSDECOMBINATION REACTIONS

2. Some metallic hydroxides (bases), when heated, decompose to form the metal oxide and water.

Example: Sodium hydroxide is heated.

NaOH

8.2 Types of ReactionsDECOMBINATION REACTIONSDECOMBINATION REACTIONS

2. Some metallic hydroxides (bases), when heated, decompose to form the metal oxide and water.

Example: Sodium hydroxide is heated.

NaOH H2O + ______

8.2 Types of ReactionsDECOMBINATION REACTIONSDECOMBINATION REACTIONS

2. Some metallic hydroxides (bases), when heated, decompose to form the metal oxide and water.

Example: Sodium hydroxide is heated.

NaOH H2O + Na2O…but it’s not balanced.

8.2 Types of ReactionsDECOMBINATION REACTIONSDECOMBINATION REACTIONS

2. Some metallic hydroxides (bases), when heated, decompose to form the metal oxide and water.

Example: Sodium hydroxide is heated.

2NaOH H2O + Na2OSodium hydroxide “yields” water and sodium oxide

8.2 Types of ReactionsDECOMBINATION REACTIONSDECOMBINATION REACTIONS

2. Some metallic hydroxides (bases), when heated, decompose to form the metal oxide and water.

Example: Calcium hydroxide is heated.

Ca(OH)2

8.2 Types of ReactionsDECOMBINATION REACTIONSDECOMBINATION REACTIONS

2. Some metallic hydroxides (bases), when heated, decompose to form the metal oxide and water.

Example: Calcium hydroxide is heated.

Ca(OH)2 H2O + _____

8.2 Types of ReactionsDECOMBINATION REACTIONSDECOMBINATION REACTIONS

2. Some metallic hydroxides (bases), when heated, decompose to form the metal oxide and water.

Example: Calcium hydroxide is heated.

Ca(OH)2 H2O + CaOCalcium hydroxide “yields” water and calcium oxide

8.2 Types of ReactionsDECOMBINATION REACTIONSDECOMBINATION REACTIONS

3. Some metallic CARBONATES, when heated, decompose to form the metal oxide and carbon dioxide gas.

Metallic carbonate metal oxide and carbon dioxide

8.2 Types of ReactionsDECOMBINATION REACTIONSDECOMBINATION REACTIONS

3. Some metallic CARBONATES, when heated, decompose to form the metal oxide and carbon dioxide gas.

Examples of metallic carbonates:

Copper (II) carbonate CuCO3

CuCO3

Metallic carbonate metal oxide and carbon dioxide

8.2 Types of ReactionsDECOMBINATION REACTIONSDECOMBINATION REACTIONS

3. Some metallic CARBONATES, when heated, decompose to form the metal oxide and carbon dioxide gas.

Examples of metallic carbonates:

Copper (II) carbonate CuCO3

CuCO3 ____ + CO2

Metallic carbonate metal oxide and carbon dioxide

8.2 Types of ReactionsDECOMBINATION REACTIONSDECOMBINATION REACTIONS

3. Some metallic CARBONATES, when heated, decompose to form the metal oxide and carbon dioxide gas.

Examples of metallic carbonates:

Copper (II) carbonate CuCO3

CuCO3 CuO + CO2

Metallic carbonate metal oxide and carbon dioxide

8.2 Types of ReactionsDECOMBINATION REACTIONSDECOMBINATION REACTIONS

3. Some metallic CARBONATES, when heated, decompose to form the metal oxide and carbon dioxide gas.

Examples of metallic carbonates:

Copper (II) carbonate CuCO3

CuCO3 CuO + CO2Copper (II) carbonate “yields” copper (II) oxide and carbon dioxide

Metallic carbonate metal oxide and carbon dioxide

8.2 Types of ReactionsDECOMBINATION REACTIONSDECOMBINATION REACTIONS

4. Some metallic CHLORATES, when heated, decompose to form the

metal chloride and oxygen gas.

Change this in your notes!!!

8.2 Types of ReactionsDECOMBINATION REACTIONSDECOMBINATION REACTIONS

4. Some metallic CHLORATES, when heated, decompose to form the metal chloride and oxygen gas.

Examples of metallic chlorates: Potassium chlorate KClO3

Aluminum chlorate Al(ClO3)3

Magnesium chlorate Mg(ClO3)2

8.2 Types of ReactionsDECOMBINATION REACTIONSDECOMBINATION REACTIONS

4. Some metallic CHLORATES, when heated, decompose to form the metal chloride and oxygen gas.

Examples:

Potassium chlorate is heated

8.2 Types of ReactionsDECOMBINATION REACTIONSDECOMBINATION REACTIONS

4. Some metallic CHLORATES, when heated, decompose to form the metal chloride and oxygen gas.

Examples:

Potassium chlorate is heated

KClO3

8.2 Types of ReactionsDECOMBINATION REACTIONSDECOMBINATION REACTIONS

4. Some metallic CHLORATES, when heated, decompose to form the metal chloride and oxygen gas.

Examples:

Potassium chlorate is heated

KClO3 _____ + O2

Metallic chlorate metal chloride and oxygen gas

8.2 Types of ReactionsDECOMBINATION REACTIONSDECOMBINATION REACTIONS

4. Some metallic CHLORATES, when heated, decompose to form the metal chloride and oxygen gas.

Examples:

Potassium chlorate is heated

KClO3 KCl + O2Potassium chlorate “yields” potassium chloride and oxygen gas

Metallic chlorate metal chloride and oxygen gas

8.2 Types of ReactionsDECOMBINATION REACTIONSDECOMBINATION REACTIONS

5. Some binary compounds, when heated or treated with electricity, will decompose into their elements.

Binary compounds are made of just 2 different elements

8.2 Types of ReactionsDECOMBINATION REACTIONSDECOMBINATION REACTIONS

5. Some binary compounds, when heated or treated with electricity, will decompose into their elements.

Examples of binary compounds:

Water H2O (same as H OH)

Silver oxide Ag2O

Iron (II) oxide FeO

Mercury (II) oxide HgO

8.2 Types of ReactionsDECOMBINATION REACTIONSDECOMBINATION REACTIONS

5. Some binary compounds, when heated or treated with electricity, will decompose into their elements.

Examples:

Water decomposes when electricity is applied

8.2 Types of ReactionsDECOMBINATION REACTIONSDECOMBINATION REACTIONS

5. Some binary compounds, when heated or treated with electricity, will decompose into their elements.

Examples:

Water decomposes when electricity is applied

H2O H2 + O2 Water Hydrogen gas + Oxygen gas

…but it’s not balanced.

8.2 Types of ReactionsDECOMBINATION REACTIONSDECOMBINATION REACTIONS

5. Some binary compounds, when heated or treated with electricity, will decompose into their elements.

Examples:

Water decomposes when electricity is applied

2H2O 2H2 + O2 Water Hydrogen gas + Oxygen gas

8.2 Types of ReactionsDECOMBINATION REACTIONSDECOMBINATION REACTIONS

Some binary compounds, when heated or treated with electricity, will decompose into their elements.

Examples:

Silver oxide decomposes when heated

8.2 Types of ReactionsDECOMBINATION REACTIONSDECOMBINATION REACTIONS

Some binary compounds, when heated or treated with electricity, will decompose into their elements.

Examples:Silver oxide decomposes when heated

2Ag2O Silver oxide

8.2 Types of ReactionsDECOMBINATION REACTIONSDECOMBINATION REACTIONS

Some binary compounds, when heated or treated with electricity, will decompose into their elements.

Examples:

Silver oxide decomposes when heated

2Ag2O 2Ag + O2 Silver oxide Silver + Oxygen gas

8.2 Types of ReactionsDECOMBINATION REACTIONSDECOMBINATION REACTIONS

Practice Examples:

With the person next to you, predict the product in

the following decomposition reactions.

(Use the from above!)

8.2 Types of ReactionsDECOMBINATION REACTIONSDECOMBINATION REACTIONS

Practice Examples: Write the balanced equations for the following decompositions…

(Use the from above!)

1. Calcium carbonate solid is heated

8.2 Types of ReactionsDECOMBINATION REACTIONSDECOMBINATION REACTIONS

Practice Examples: Write the balanced equations for the following decompositions…

(Use the from above!)

1. Calcium carbonate solid is heated

Ca(OH)2 CaO + CO2

8.2 Types of ReactionsDECOMBINATION REACTIONSDECOMBINATION REACTIONS

Practice Examples: Write the balanced equations for the following decompositions…

(Use the from above!)

2. Magnesium chlorate solid is heated

8.2 Types of ReactionsDECOMBINATION REACTIONSDECOMBINATION REACTIONS

Practice Examples: Write the balanced equations for the following decompositions…

(Use the from above!)

2. Magnesium chlorate solid is heated

Mg(ClO3)2 MgCl2 + O2

8.2 Types of ReactionsDECOMBINATION REACTIONSDECOMBINATION REACTIONS

Practice Examples: Write the balanced equations for the following decompositions…

(Use the from above!)

3. Hydroiodic acid is heated

8.2 Types of ReactionsDECOMBINATION REACTIONSDECOMBINATION REACTIONS

Practice Examples: Write the balanced equations for the following decompositions…

(Use the from above!)

3. Hydroiodic acid is heated

2HI H2 + I2

8.2 Types of ReactionsDECOMBINATION REACTIONSDECOMBINATION REACTIONS

Practice Examples: Write the balanced equations for the following decompositions…

(Use the from above!)

4. Magnesium hydroxide is heated

8.2 Types of ReactionsDECOMBINATION REACTIONSDECOMBINATION REACTIONS

Practice Examples: Write the balanced equations for the following decompositions…

(Use the from above!)

4. Magnesium hydroxide is heated

Mg(OH)2 H2O + MgO

8.2 Types of ReactionsDECOMBINATION REACTIONSDECOMBINATION REACTIONS

Practice Examples: Write the balanced equations for the following decompositions…

(Use the from above!)

5. Sulfurous acid is heated

8.2 Types of ReactionsDECOMBINATION REACTIONSDECOMBINATION REACTIONS

Practice Examples: Write the balanced equations for the following decompositions…

(Use the from above!)

5. Sulfurous acid is heated

H2SO3 H2O + SO2

For the TEST on Friday…This concludes any new material we will be

covering before Christmas Break. You are strongly encouraged to prepare for the test which has the following Objectives on it:

Balancing EquationsPredicting Combination ReactionsPredicting Decomposition ReactionsDistributive Practice: Review from past

Tests