1. Chemical Reactions Introduction
Unit 5
Chemical Reactions Introduction

2. Chemical Reactions
A chemical reaction occurs when a substance (or substances) change(s) into a new substance(s) with a new identity.
Chemical bonds are broken, and atoms rearrange and form new bonds.
A chemical equation is used to
express the chemical reaction.

3. A + B → C + D Chemical Reactions Reactants
The matter that is present before the reaction takes place.
Reactants are always to the left of the arrow.
A + B → C + D

4. A + B → C + D Chemical Reactions Products
The matter that is present after the reaction takes place
Products are always to the right of the arrow
A + B → C + D

5. A + B → C + D Chemical Reactions Yield Sign
The arrow, →, is read as the word, yields.
What the yield sign is saying is that the reactant(s), when combined or dissolved, form the product(s).
A + B → C + D

6. Chemical Reactions Zn + 2AgNO3 → Zn(NO3)2 + 2Ag
The subscripts show how many of each element.
Zn + 2AgNO3 → Zn(NO3)2 + 2Ag
Ex. There is 1 Zinc
There are 2 Nitrates
Coefficients - How many of the entire molecule. Acts as a multiplier for the entire compound AgNO3
There are 2 - Silver Nitrates

7. Chemical Reactions Symbols often seen in chemical equations……
(s) – Solid:A solid precipitate can form
as a result of a chemical reaction
(l) - Liquid
(g) - Gas
Often seen as bubbles
(aq) - Aqueous Solution
Compound is dissolved in water

8. 5 Types of Chemical Reactions Synthesis Decomposition Single Replacement Double Replacement Combustion
Synthesis - 2 or more reactants combine to form a single product.
A + B → AB
4Fe + 3O2 → 2Fe2O3

9. Types of Chemical Reactions
Decomposition - One reactant yields two or more products.
AB → A + B
H2SO3 → H2O + SO2
Single Replacement - One element takes the place of another element.
A + BC → AB + C
Cl2 + 2NaBr → 2NaCl + Br2

10. Types of Chemical Reactions
Double Replacement - The positive ions of two ionic compounds switch places.
At least one of the products will be a precipitate, water, or gas.
AB + CD → AD + CB
Pb(NO3)2 (aq) + 2 KI (aq) → PbI2 (s) + 2 KNO3 (aq)

11. Types of Chemical Reactions
Combustion - Burning an organic substance.
The products are always CO2 and H20.
****Often a hydrocarbon combines with O2.
Combustion is what makes an engine run.
CH4 + 2O2 → CO2 + 2H20

12. HUSKY HELP
IF you want to retake the test from Tuesday… get out your completed Remediation sheet off of Weebly 
HMWK:
Work on HP Part 4—Research Paper .. Individually
Due Nov. 15th

13. Thursday…
Get a Lab worksheet off the front table… read over it and get ready for a short lab
By the end of this unit… you will write a balanced chemical equation for what is occurring in the lab
HMWK:
Work on HP Part 4—Research Paper .. Individually
Due Nov. 15th

14. Types of Chemical Reactions

15. Get out your notes from yesterday…
Get a sheet of construction paper… fold it into four squares.
You will create one cartoon for each of the following chemical reactions in each square. Make sure you label each one correctly.
1. Synthesis
2. Decomposition
3. Single replacement
4. Double replacement
Do not copy my example.
Then…. You will have one person report out
and show them to the class and then we will
Hang them in the hallway

16. Warm-up…. 10-28-16 What type of Reaction is shown?
NaBr + Ca(OH)2 → CaBr2 + NaOH
NH3+ H2SO4 → (NH4)2SO4
C5H9O + O2 → CO2 + H2O
Pb + H3PO4 → H2 + Pb3(PO4)2
CaCO3 → CaO + CO2
HBr + Al(OH)3 → H­2O + AlBr3

17. What type of Reaction is shown?
NaBr + Ca(OH)2 → CaBr2 + NaOH
NH3+ H2SO4 → (NH4)2SO4
C5H9O + O2 → CO2 + H2O
Pb + H3PO4 → H2 + Pb3(PO4)2
CaCO3 → CaO + CO2
HBr + Al(OH)3 → H­2O + AlBr3
Double Replacement
Synthesis
Combustion
Single Replacement
Decomposition

18. Predicting Products Predict the products:
If there are two elements as reactants, then the reaction is SYNTHESIS. If there is one reactant, then the reaction is DECOMPOSITION.
Predict the products:
Mg + O2 →
Ca + Cl2 →
Li2O →
ZnCl2 →
K + S →
MgO
CaCl2
Li + O2
Zn + Cl2
K2S

19. Predicting Products For Single Replacement reactions:
* Use ACTIVITY SERIES (in your reference
tables)* The element that is by itself MUST be
hig her on the chart than the element in the
compound for the reaction to occur
Metal replace Metals
Nonmetals replace Nonmetals

20. Will the reaction occur?
Fe (s) + Pb(NO3)2 (aq) →
Ni (s) + MgCl2 (aq) →
Cl2 (aq) + NaI (aq) →
Ca (s) + CuBr2 (aq) →
K (s) + Al(NO3)3 (aq) →
I2 (s) + MnBr2 (aq) →
Mg (s) + AgNO3 (aq) →
Cl2 (s) + SrF2 (aq) →
YES NO
Take the reactions that WILL occur and predict the products.