1. Objectives:
The students will be able to state the distinguishing characteristics of a synthesis reaction.
The students will be able to state the distinguishing characteristics of a decomposition reaction.
The students will be able to identify the role water plays in dehydration synthesis and hydrolysis.
Assignment: None
Focus:
In the graph to the right, the red line represents the __________ and the blue line represents the __________ as a reaction proceeds.

2. Types of Reactions There are millions of reactions.
They are classified into several categories.
We will learn 6 types. *

3. Synthesis Reactions Ca (s) +O2 (g) → CaO (s)
Also called combination reactions
A reaction in which two or more substances combine to form a new compound.
A + B → AB
Ca (s) +O2 (g) → CaO (s)
Photosynthesis gets its name from being a synthesis reaction. *

4. A simulation of the reaction: 2H2 + O2 → 2H2O

5. Dehydration Reactions are synthesis reactions that help build big molecules in the human body
In dehydration reactions, smaller molecules called monomers join together into bigger molecules called polymers while losing water molecules.
One of the monomers loses a hydroxide ion (OH-) and the other monomer loses a hydrogen ion (H+).
The two unstable monomers join together to form a stable polymer, and the (OH-) and (H+) combine, forming water (H2O).

6. Decomposition Reactions
decompose = fall apart
A reaction in which a single compound breaks down into two or more simpler compounds
Usually requires activation energy
AB → A + B
Examples include digestion and the “cracking” of crude oil into gasoline. *

7. Decomposition Reactions and Electrolysis
Electrolysis is a process in which electric current is used to produce a chemical reaction, such as the decomposition of water.
H2O
H2 (g) + O2 (g) *

8. Hydrolysis Reactions are decomposition reactions that help break down big molecules in the human body
Hydrolysis reactions split certain molecules into two parts by adding a molecule of water.
One fragment of the original molecule gains a hydrogen ion (H+) from the water molecule.
The other fragment of the original molecule gains the hydroxide ion (OH−) from the water molecule.

9. Objectives:
The students will review the distinguishing characteristics of synthesis and decomposition reactions.
The students will be able to state the distinguishing characteristics of a combustion reaction.
Assignment: None
Focus:
Dehydration reactions are synthesis reactions involve removing _______________ from simpler molecules so that they can join together.
a. water molecules c. OH and H
b. C and H d. both answers a and c
Photosynthesis is an example of a(n) ____________________ chemical reaction in which plants use sunlight to make glucose and oxygen.
a. endothermic c. synthesis
b. exothermic d. a+c

10. Combustion Reactions
The oxidation reaction of an organic compound, in which heat is released.
Organic compounds often contain carbon which reacts with oxygen during combustion.
CH4 + O → CO2 + H2O
C3H8 + O2 → CO2 + H2O
C6H12O6 + O2 → CO2 + H2O

11. The charcoal used in a grill is basically carbon
The charcoal used in a grill is basically carbon. The carbon reacts with oxygen to yield carbon dioxide. The chemical equation for this reaction is C + O2 → CO2

12. Products of combustion reactions depend on the amount of oxygen available
If the proper level of oxygen is available during combustion, the products will be carbon dioxide and water.
However, if oxygen levels are low, carbon monoxide can be produced instead
Carbon monoxide is colorless, odorless and highly toxic
If oxygen levels are even lower, tiny bits of carbon, known as soot, will form
You can tell when oxygen supply is limited because the smoke given off is often dark and sooty

13. Objectives:
The students will be able to state the distinguishing characteristics of a single replacement reactions.
Assignment: None
Focus:
When methane burns in the presence of insufficient oxygen, the products of the reaction are water and ____________________.
a. Carbon dioxide c. Carbon(Soot)
b. Carbon Monoxide d. b+c
When methane reacts with abundant amounts of oxygen, the products are
a. carbon dioxide and water. c. soot and water.
b. carbon monoxide and water. d. simple sugar and oxygen.

14. Single Replacement Reactions
Also referred to as single displacement/exchange reactions
A reaction in which one element or radical takes the place of another element or radical in a compound.
Reactants 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 *

15. Single Replacement Reactions
Generally, in single replacement reactions, a more reactive element will take the place of a less reactive one. *

16. Single Replacement Reactions
Alkali metals engage in single replacement reactions with water.
The result of putting an alkali metal in water is the formation of a metal ion (ex. K+1), the hydroxide ion (OH-1), and the release of hydrogen gas (H2).
Since Alkali metals get more reactive as you move down the column, the reactions become more explosive from Lithium to Francium

17. Double Replacement Reactions
A reaction in which a gas, solid precipitate, or a molecular compound forms from the apparent exchange of atoms or ions between two compounds
AB + CD → AD + CB
ZnS HCl →
ZnCl + H2S
AgNO3 + NaCl →
AgCl + NaNO3

19. Acid /Base - Reactions HCl (aq) → H+(aq) + Cl-(aq)
Acids: An acid is a substance which, when dissolved in water, releases protons or donates protons in solution.
HCl (aq) → H+(aq) Cl-(aq)
HCl (aq) + H2O (l) → H3O+(aq) + Cl-(aq)
Bases: A base is a substance which, when dissolved in water, forms a metal ion and a hydroxide ion (OH-) or donates hydroxide in solution.
NaOH(aq) → Na+(aq) + OH-(aq)
So When acids and bases combine, what will the products of the reaction be?
Use HCl(aq) and NaOH(aq) as an example.
Proton—sometimes written as H3O+

20. Acid/Base reactions are double replacement reactions with water and salt as a product
Acid + Base → Water + Salt
H2O + NaC2H3O2
HC2H3O2 + NaOH →
H2SO4 + Mg(OH)2 →
2H2O + MgSO4
Write the ionic equations

21. How to recognize which type
Look at the reactants
Element(E), Compound(C)
One Product = Synthesis
One Reactant = Decomposition
E + C ➡️ E + C = Single Replacement
C + C ➡️ C + C = Double Replacement
“H” C + “-OH” C ➡️ Salt + Water = Acid/Base
“C” C + O2 ➡️CO2 + H2O = Combustion *

22. Objectives:
The students will distinguish among the six general types of chemical reactions.
The students will classify elements as being oxidised or reduced by analyzing electron transfers during a reaction.
Assignment: “What’s your Reaction” Activity due Wednesday
Focus:
The reaction Pb(NO3)2(aq) + 2KI(aq) →PbI2(s) + 2KNO3(aq) is a
a. double-replacement reaction. c. decomposition reaction.
b. synthesis reaction. d. combustion reaction.
The reaction Mg(s) + 2HCl(aq) → H2(g) + MgCl2(aq) is a
a. composition reaction. c. single-replacement reaction.
b. decomposition reaction. d. double-replacement reaction.

23. Electrons in Chemical Reactions
Another way of understanding reactions is to look at them as transfers of electrons
In chemical reactions, some atoms gain electrons and some atoms lose electrons
An atom is said to be oxidized if it gives up electrons or gains oxygen atoms as part of a chemical reaction.
An atom is said to be reduced if it accepts electrons or loses oxygen atoms.
Since these processes are linked, in such reactions one or more atoms is reduced and one or more atoms is oxidized.
Oxidation-Reduction Reactions (also called redox reactions) - Any chemical change in which one species is oxidized ( loses electrons) and another species is reduced( gains electrons)

24. Combustion and Respiration are oxidation- reduction reactions

25. Radicals
Reactions that involve the breaking of covalent bonds rather than ionic bonds often cause the formation of radicals.
Radicals - An organic group that has one or more electrons available for bonding.
When a covalent bond is broken such that at least one unpaired electron is left on each fragment, a radical is formed.
Radicals react quickly to form new compounds.
They are often referred to as free radicals.