S-133

• Write the formula for– Palladium (IV) Oxide– Calcium Fluoride– Cadmium (II) NitrideWrite the name for

- Al2S3

- Rb3P

- CrO3

SPS2. Students will explore the nature of matter, its classifications, and its system for naming types of matter.d. Demonstrate the Law of Conservation of Matter in a chemical reaction.e. Apply the Law of Conservation of Matter by balancing the following types of chemical equations;

- Synthesis- Decomposition- Single Replacement- Double Replacement

Unit 7 Chemical Reaction

What is the law of conservation of mass?Why must chemical equations be balanced?Why do chemists use the mole?How can you calculate the mass of a reactant or product in a

chemical reaction?

7.1 Describing Reactions

• Chemical Equations– Reactants – the substances that are

present before a reaction– Products – the substances present after a

reaction is complete– Always given in the form

Reactants Products– Example:Carbon + Oxygen Carbon

Dioxide

– Or C + O2 CO2

7.1 Describing ReactionsWhat is the law of conservation of mass?

• Writing Equations - Practice– Copper and Oxygen make Copper (II)

Oxide– Magnesium and Hydrogen Chloride make

Hydrogen and Magnesium Chloride

– Ethylene (C2H4) burns with Oxygen to produce Carbon Dioxide and Water.

– Hydrogen and Chlorine combine to make Hydrogen Chloride

7.1 Describing ReactionsWhat is the law of conservation of mass?

• Conservation of Mass– Mass is not created or destroyed in a

chemical reaction– For practical purposes

• Same types of atoms before and after a reaction

• Same number of each type of atom before and after

– Equations must show this– They are called balanced equations

7.1 Describing ReactionsWhat is the law of conservation of mass?

S-134

• Write the formula for– Dinitrogen Trioxide– Copper (II) oxide– Dinitrogen PentaoxideWrite the name for

- CCl4- CrBr3

- Mo2O5

S-135

• Write the equation for a reaction of hydrogen sulfide with aluminum oxide to make aluminum sulfide and water.

• Balancing Equations– If an equation does not have the same

elements on both sides, it is a false equation • Can not actually occur

– Coefficient – a number placed in front of a substance in a chemical equation• Used to balance equations

7.1 Describing ReactionsWhy must chemical equations be balanced?

• Balancing Equations - Steps– First write out the equation

• Hydrogen and Oxygen make water becomes

• H2 + O2 H2O

– List the elements on each sideH-2 H-2O-2 O-1

– Add substances until both sides are equal

7.1 Describing ReactionsWhy must chemical equations be balanced?

• Balancing Equations - Practice– Copper and Oxygen make Copper (II)

Oxide– Magnesium and Hydrogen Chloride make

Hydrogen and Magnesium Chloride– Ethylene (C2H4) burns with Oxygen to

produce Carbon Dioxide and Water.

7.1 Describing ReactionsWhy must chemical equations be balanced?

S-137

• Balance the following equations

H2SO4 + Al(OH)3 Al2(SO4)3 + H2O

• Counting With Moles– A unit of measurement– Equals 6.02 x 1023 of anything– Used only to count atoms, molecules,

formula unit– One mole of an element is equal to its

atomic mass converted to grams (put a g beside the number)

7.1 Describing ReactionsWhy do chemists use the mole?

18

Ar39.95

Argon

• Molar Mass– For an element equal to its atomic mass– For a compound

• For each element – multiply the mass x the number of that element in the compound

• Add the total

7.1 Describing ReactionsHow can you calculate the mass of a reactant or product in a reaction?

• Molar Mass-Example– C2H4

– Carbon 12.01g x 2 = 24.02g– Hydrogen 1.01g x 4 = 4.04g– Total 28.06

7.1 Describing ReactionsHow can you calculate the mass of a reactant or product in a reaction?

• Molar Mass-Example– Pb(OH)4

7.1 Describing ReactionsHow can you calculate the mass of a reactant or product in a reaction?

S-137

• What is the molar mass of

Al2(SO4)3

What are the general types of chemical reactions?

7.2 Types of Reactions

• Classifying Reactions– Describe how reactants interact to form

products– Help to predict the products of

reactions

Types of ReactionsWhat are the general types of reactions?

• Synthesis– Two or more substances react to form a

single substance– Pattern A + B AB– Always has one product– Examples

• 2Na + Cl2 2NaCl

• 2H2 + O2 2H2O

Types of ReactionsWhat are the general types of reactions?

• Decomposition– One substance breaks apart into two or

more products– Pattern AB A + B– Always has one reactant– Examples

• CaCO3 CaO + CO2

• 2H2O 2H2 + O2

Types of ReactionsWhat are the general types of reactions?

• Single Replacement (Displacement)– A compound switches parts with an

element– Pattern A + BC B + AC– Always has one element and one

compound on each side– Examples

• Cu + 2AgNO3 2Ag + Cu(NO3)2

• 2K + 2H2O H2 + KOH

Types of ReactionsWhat are the general types of reactions?

• Double Replacement (Displacement)– Two compounds switch parts– Often results in the formation of a

precipitate– Pattern AB + CD AD + CB– Always has two compounds on each side– Examples

• Pb(NO3)2 + 2KI PbI2 + 2KNO3

• CaCO3 + 2HCl CaCl2 + H2CO3

Types of ReactionsWhat are the general types of reactions?

• Combustion– Reacts rapidly with oxygen– Everything combines with oxygen

– Pattern AB + O2 AO + BO

– Always has oxygen as a reactant– Examples

• CH4 + O2 CO2 + 2H2O

• 2Ca + O2 2CaO

Types of ReactionsWhat are the general types of reactions?

S-138

• Balance the following reactions and tell what type(s) they are.

1. Pb(NO3)2 + HCl PbCl2 + HNO3

2. Ca + HCl CaCl2 + H2

S-139

• Write out the reaction, then balance it and tell what type it is.

1. Mercury reacts with oxygen to form Mercury (II) Oxide