Chapter 7

Chapter 7 Day 1OBJECTIVE:

Interpret chemical reactions for reactants and products,

energy needs and conservation of mass. Do Now: Chapter 7 Vocabulary TURN IN: Model Molecule Lab

Today: Chapter 7 – Chemical Reactions notes

Types of Chemical Reactions Cartoon Chemistry

Homework: Finish Cartoon Chemistry

Unit 2 Chapter 7 Day 2 OBJECTIVE:

Interpret chemical reactions for reactants and products,

energy needs and conservation of mass.

Do Now: Types of Chemical Reactions

Today: The Balancing Act packet –

Notes and Worksheets Homework:

Balancing Equations

Unit 2 Chapter 7 Day 3 OBJECTIVE:

Interpret chemical reactions for reactants and products,energy needs and conservation of mass.

• Do Now: • Balancing Review

• Today:• Homework review – Balancing Equations• DVD Field Trips – Chapters 6 & 7• Test review / Study Guide…

What did we learn again?• START Test Review packet

• Homework:• COMPLETE Test Review packet

Unit 2 Chapter 7 Day 4 OBJECTIVE:

Demonstrate knowledge of matter, phase, atomic structure, the periodic table, chemical reactions and

conservation of mass.

• Do Now: • Vocabulary Bingo - Chapters 4,5,6,7

• Today:• Review Chemistry Unit Study Guide• Spring Balance Challenge

• Homework:• STUDY FOR CHEMISTRY UNIT TEST

Unit 2 Chapter 7 Day 5OBJECTIVE:

Demonstrate knowledge of matter, phase, atomic structure, the periodic table, chemical reactions and

conservation of mass.• Do Now:

• Do Now Folder #6-7 (8 pages)• Today:

• Chemistry Unit Test • Unit 2 Notebook Chap 6 & 7 (21 pages)

• Homework: Current Events – 2nd Chance

Experiments

Extra Credit Balance Challenges

A) ____ CoBr3 + ____ CaSO4 ____ CaBr2 + ____ Co2(SO4)3

B) ____ S    +   ____ HNO3      ____ H2SO4   +    ____ NO2   +   ____ H2O 

C) ____ Cu   +  ____  HNO3   ____ Cu(NO3)2  + ____ NO   +    ____ H2O

A   2 CoBr3 + 3 CaSO4 3 CaBr2 + Co2(SO4)3

  

B S    +   6 HNO3   ->   H2SO4   +  6 NO2   +   2 H2O 

     

C 3 Cu   +   8HNO3   -> 3 Cu(NO3)2    +  2 NO   +  4  H2O 

Chapter 7

Unit 2 Chapter 6/7 OBJECTIVE:

Investigate five indicators of chemical reations.

• Do Now: • ASK Review

• Today:• Identifying Chemical Reaction Lab

• Homework:• Missing Assignments for MP1?

Wednesday 11/12and Thursday 11/13

Indicators of chemical reactions

Formation of a gas

Emission of light or heat

Formation of a precipitate

Color change

Emission of odor

All chemical reactions:

Create 1 or more new substancesHave two partsReactants - the substances you start

withProducts- the substances you end up

with

The reactants turn into the products.Reactants ® Products

In a chemical reaction…

Bonds between atoms in reactants are brokenAtoms rearrange and form new bonds in the productsAtoms aren’t created or destroyed…Mass is CONSERVED in a chemical reaction..This is called…

Law of Conservation of Mass

All chemical reactions are accompanied by a change in energy.  It takes energy to break bonds AND energy is released when bonds are broken!

Exothermic - reactions that release energy to their surroundings (usually in the form of heat)

Endothermic - reactions that need to absorb heat from their surroundings to proceed.

Reaction Energy

Types of Reactions

Synthesis ReactionsTWO elements combine to make one compound. (Polyatomics count as one)

A + B ® AB

Na + Cl2 ® NaCl

Ca +O2 ® CaO

SO3 + H2O ® H2SO4 We can predict the products if there are two elements.

Mg + N2 ®

Mg3N2

Decomposition Reactionsdecompose = fall apart, Falls apart into its elementsMade up of only two elementsone compound (reactant) falls apart into two or more elements or compounds.Usually requires energy

AB ® A + B

NaCl ® Na + Cl2

CaCO3 ® CaO + CO2

Single Replacement

One element replaces anotherReactants must be an element and a compound.Products will be a different element and a different compound.

A + BC ® AC + B 2Na + SrCl2 ® Sr + 2NaCl

F2 + LiCl ® LiF + Cl2

Double Replacement

Two things replace each other.Usually in water solution

AB + CD ® AD + CB

AgNO3 + NaCl ® AgCl + NaNO3

ZnS + 2HCl ® ZnCl + H2S

How to recognize which typeLook at the reactants

Element(E), Compound(C)

E + E CE + CC + C

Synthesis

Decomposition

Single replacement

Double replacement

Examples

Synthesis

Decomposition

DecompositionSingle replacement

Single replacement

Double replacement

Double replacement

H2 + O2 ®

H2O ® AgNO3 + NaCl ®

Zn + H2SO4 ® HgO ®

KBr +Cl2 ®

Mg(OH)2 + H2SO3 ®

Examples

Decomposition

Single replacement

Synthesis

Single replacement

Double replacement

CaPO4 ®

AgBr + Cl2 ®

Zn + O2 ®

HgO + Pb®

Cu(OH)2 + KClO3 ®

Identifying Chemical Reactions

_____ P + O2 → P4O10

____ Mg + O2 → MgO

____ HgO → Hg + O2

____ Al2O3 → Al + O2

____ Cl2 + NaBr → NaCl + Br2

____ H2 + N2 → NH3

S = Synthesis D = Decomposition SR = Single Replacement DR = Double Replacement

 

____ Na + Br2 → NaBr

____ CuCl2 + H2S → CuS + HCl

____ HgO + Cl2 → HgCl + O2

____ C + H2 → CH4

____ KClO3  →   KCl  +  O2 

____ S8 + F2 → SF6

____ BaCl2   +   Na2 SO4 →    NaCl   + BaSO4

Bala

ncin

g A

ct

Chemical Reactions Review…1. Is the process where physical and

chemical properties of the original substance change into a new substance with different physical and chemical properties If there is no new substance there has

been no reactionReactants enter into the reactionProducts are produced by the reaction

Chemical Reactions Review…2. Chemical equations describe

chemical reactions using symbols and numbers.

2Na + SrCl2 ® Sr + 2NaCla) Coefficients (in red)

The large numbers in front of chemical formulas.

The number of molecules of the substance in the reaction

Chemical Reactions Review…2. Chemical equations describe

chemical reactions using symbols and numbers.

2Na + SrCl2 ® Sr + 2NaClb) Subscripts (in Green)

The small numbers to the lower right of chemical symbols

Represent the number of atoms of each element is in the molecule

Chemical Reactions Review…3. Atoms can neither be created nor

destroyed during a chemical reaction…Mass MUST remain constant

You have to end up with the same number of atoms you started with, but in a different arrangement

So balanced equations have the same number of atoms on each side of the YIELDS “®“ sign

Law of Conservation of Mass

Balancing Chemical Equations

(ALWAYS USE PENCIL)1. Check for DIATOMIC molecules H2 , N2 , O2 , F2 , Cl2 , Br2 , I2 , and At2

You cannot change the subscripts of these elements in an equation… whenever they are by themselves, these must be written with the subscript 2.

Balancing Chemical Equations

2. Count the number of atoms on each side of the reaction:

___Na + ___MgCl2 ® ___Mg + ___NaCl

Sodium=____ ® Sodium=____

Magnesium=____ ® Magnesium

=____ Chlorine=____ ®

Chlorine=____

1

1

2

1

1

1

Balancing Chemical Equations

2. Balance the metals first then the nonmetals

___Na + ___MgCl2 ® ___Mg + ___NaCl

Sodium=____ ® Sodium=____

Magnesium=____ ® Magnesium

=____ Chlorine=____ ®

Chlorine=____

1

1

2

1

1

1X 2

2

X 2

2

X 2

Balancing Chemical Equations

3. If they are in your equation, balance OXYGEN

then HYDROGEN last4. Recount all atoms and check your work!

Work from the bottom to top until you find any error.

5. If every coefficient will reduce, rewrite in the simplest whole number ratio

Balancing Chemical EquationsLets try an easy one:

___H2 + ___O2 ® ___H2O

Hydrogen=____ ® Hydrogen=____

Oxygen=____ ® Oxygen =____

2

2

2

1X 2

2

X 4

2

X 4

Balancing Chemical EquationsLets try one more:

___Na + ___HCl ® ___H2 + ___NaCl

Sodium=____ ® Sodium =____

Hydrogen=____ ® Hydrogen=____

Chlorine=____ ® Chlorine =____

1

1

1

1

2

1

X 2

2

X 2 X 2

2

X 2X 2

2

Balancing Act

1. ___Mg + ___O2 ® ___MgO

2. ___Ca + ___O2 ® ___CaO

3. ___H2O2 ® ___H2O + ___O2

4. ___N2 + ___H2 ® ___NH3

5. ___Cu2O + ___C ® ___Cu+ ___CO2

• Spontaneous Reactions - Reactions that proceed immediately when two substances are mixed together.  Not all reactions proceed spontaneously. 

Reaction Energy

• Activation Energy – the amount of energy that is required to start a chemical reaction.

• Once activation energy is reached the reaction continues until you run out of material to react.  

Diatomic elements

There are 8 elements that never want to be alone.They form diatomic molecules.H2 , N2 , O2 , F2 , Cl2 , Br2 , I2 , and At2

What is a catalyst?

A substance that can help the reactants in a chemical reaction react with each other fasterSpeeds up a reaction without being changed by the reaction…it does NOT become part of the reaction.Enzymes are biological or protein catalysts.

Summary of Symbols