1. 1 – Nature of Chemical Reactions 4 – Reaction Rates and Equilibrium
2 – Chemical Equations
3 - Reaction Types
4 – Reaction Rates and Equilibrium

2. State Standards
CLE – Apply the Laws of Conservation of Mass/Energy to balance chemical equations
CLE.3202.Inq.4 – Apply qualitative and quantitative measures to analyze data and draw conclusions that are free of bias
CLE.3202.Inq.6 – Communicate and defend scientific findings

3. 1 - Nature of Chemical Reactions
Key Questions :
When do chemical reactions take place?
What is the role of energy in chemical reactions?

4. Chemical Reactions Everyday occurrences are reactions ( rxns )
Growing, ripen, decay, burn
Chemical reactions stem from chemical changes
How do you tell that a chemical change happens?

5. Chemical Reactions Atoms are rearranged ( to form new substance )
Reactant – substance participating in rxn
Product – substance being formed by rxn

6. Demonstration Add vinegar ( acetic acid ) to baking soda
CO2 is produced
What evidence of a reaction is obsered?

7. Energy & Chemical Reactions
Energy factors into the state of matter
Energy also plays a role in changes of state
Chemical changes use energy also
Same for chemical rxns

8. Chemical Reactions Involve changes in energy ALWAYS
Energy is required to break bonds
Forming bonds releases energy

9. Chemical Reactions Energy is conserved in rxns
Exothermic – Rxns that release energy
Endothermic – Rxns that absorb energy

10. Endothermic - Exothermic

11. Photosynthesis
An endothermic rxn

12. 1 - Nature of Chemical Reactions
Key Questions :
When do chemical reactions take place?
What is the role of energy in chemical reactions?

13. 2 - Chemical Equations Key Questions : What is a chemical equation?
What can a balanced chemical equation tell you?

14. Describing Reactions Can write a word equation
A chemical equation uses symbols to represent a chemical reaction and shows the relationship between the reactants and products

15. Conservation of Mass An equation must be balanced
CH4 + O2  CO2 + H2O ( NOT BALANCED )
CH4 + 2O2  CO2 + 2H2O ( BALANCED )
Balance by adding coefficients so that there are EQUAL NUMBERS OF EACH ELEMENT on both sides of the “Yield” sign

16. Balanced Equations & Mole Ratios
A balanced equation indicates the molar ratio
This is the proportion of reactants and products
Or relative amounts of a reactant to product
CH4 + 2O2  CO2 + 2H2O
Molar Ratio of methane to carbon dioxide?
Molar ratio of methane to oxygen?

17. Molar Ratios can be shown as MASS
How do we do this?

18. 2 - Chemical Equations Key Questions : What is a chemical equation?
What can a balanced chemical equation tell you?

19. 3 – Reaction Types Key Questions :
How does learning about reaction types help in understanding chemical reactions?
In which kinds of chemical reactions do the numbers of electrons in atoms change?

20. Classifying Reactions
Can use patterns to identify kinds of chemical reactions and to predict the products of the chemical reactions
For example : small molecules join to form a larger one by a certain type of reaction

21. Synthesis Reactions
Synthesis reactions occur when multiple substances combine to form a new compound
General form : A + B  AB
Single compound formed
Example : plastic ( polymers – remember GOOP? )

22. Decomposition Reactions
Decomposition occurs when substances are broken apart ( Opposite of Synthesis )
Cracking – large molecules of C and H (hydrocarbons) are broken apart
Digestion – similar to cracking
General form : AB  A + B

23. Combustion Reactions CH4 + 2O2  CO2 + 2H2O ( methane combustion )
When oxygen reacts with a substance ( burning )
Usually an organic material
Hydrocarbon
Plant matter ( wood ) or clothing ( cotton/polymeric )
Not always though – ammonia ( NH3 )
NH O2  NO H2O

24. Displacement Reactions
Single displacement rxn occurs when one atom appears to take the place of another
General form : AX + B  BX + A
Double displacement rxn occurs when two compounds appear to exchange ions
General form : AX + BY  BX + AY

25. Electrons & Chemical Reactions
Free radical reactions and redox reactions can be understood as changes in the numbers of electrons that atoms have
Free radical is an atom or a group of atoms that has one unpaired electron
Redox reactions ( oxidation-reduction ) occur when one substance loses electrons and another substance gains electrons

26. 3 – Reaction Types Key Questions :
How does learning about reaction types help in understanding chemical reactions?
In which kinds of chemical reactions do the numbers of electrons in atoms change?

27. 4 – Reaction Rates & Equilibrium
Key Questions :
What speeds up a reaction?
What does a catalyst do?
What happens when a reaction goes both directions

28. What is Reaction Rate? How fast a reaction proceeds
Can explain by finding the amount of products produced in a certain time interval

29. What Speeds up Reactions?
Higher temperatures
More surface area
Higher reactant concentration
( amount / vol )
Pressure / Size of compound or molecule

30. What is a catalyst?
Speeds up or slows down a reaction but is not altered by the reaction
It does not participate as a reactant or a product
In your body – ENZYMES are catalysts

31. Equilibrium Like balance when you are walking
Balance between products and reactants when a reaction goes forward and backwards

32. 4 – Reaction Rates & Equilibrium
Key Questions :
What speeds up a reaction?
What does a catalyst do?
What happens when a reaction goes both directions