1. Bell Ringer List the five of the most common reaction types
Describe how the law of conservation of mass is satisfied by balancing a chemical reaction.

2. The student will: SWBAT’s
Define five of the most common reaction types (synthesis/combination, decomposition, single-replacement, double displacement, and combustion).
Given a set of reactants and products, classify the reaction for five common reaction types.
Given the reactants, predict the anticipated products for the 5 basic forms of reaction types. (Example: for a basic decomposition reaction, the reactant is a binary ionic compound.)
Conduct multiple double-displacement chemical reactions in the qualitative analysis lab.
Perform the qualitative analysis lab. Using the observations from this lab, determine the identity of several unknown ionic compounds during a lab test.

3. The student will: SWBAT’s
Determine whether a single replacement reaction will occur based on a given set of reactants and the activity series. If a reaction occurs, predict the products that would be expected to form.
Use solubility rules to determine whether a given ionic compound is soluble or insoluble in water.
Given two ionic compounds as reactants, determine the substances anticipated to form and the physical state of each substance.
Describe a chemical reaction in different ways including using words and symbolic forms.
Describe how the law of conservation of mass is satisfied by balancing a chemical reaction.
Given a skeleton reaction, balance it by adding coefficients.

4. SWBAT Scale
4: Same as a 3.0 but I can make inferences & application to the SWBAT’s
3: I COMPLETELY understand all parts of the SWBAT
2: I understand MOST of the SWBAT’s with teacher help
1: I understand a little of the SWBAT’s but need teacher help
0: I do NOT understand any part of the SWBAT’s and need help!

5. Unit 4 “Chemical Reactions”
Adapted from: Pre-AP Chemistry
Charles Page High School
Stephen L. Cotton

6. Describing Chemical Reactions
OBJECTIVES:
Describe how to write a word equation.

7. Describing Chemical Reactions
OBJECTIVES:
Describe how to write a skeleton equation.

8. Describing Chemical Reactions
OBJECTIVES:
Describe the steps for writing a balanced chemical equation.

9. All chemical reactions…
have two parts:
Reactants = the substances you start with
Products = the substances you end up with
The reactants will turn into the products.
Reactants ® Products

10. Products
Reactants

11. Symbols in equations?
the arrow (→) separates the reactants from the products (arrow points to products)
Read as: “reacts to form” or yields
The plus sign = “and”
(s) after the formula = solid: Fe(s)
(g) after the formula = gas: CO2(g)
(l) after the formula = liquid: H2O(l)

12. Symbols in equations (cont)
(aq) after the formula = dissolved in water, an aqueous solution: NaCl(aq) is a salt water solution
­ ↑ used after a product indicates a gas has been produced: H2↑
¯ used after a product indicates a solid has been produced: PbI2↓

13. Symbols in equations (cont)
double arrow indicates a reversible reaction (more later)
shows that heat is supplied to the reaction
is used to indicate a catalyst is supplied (in this case, platinum is the catalyst)

14. Determining Phases of Substances
(g) – non-metal oxides & diatomics
(l) – water, Mercury, some hydrocarbons
(s) – Metal elements, insoluble substances (see rules)
(aq) – soluble substances (see rules)

15. In a chemical reaction
Atoms aren’t created or destroyed (according to the Law of Conservation of Mass)
A reaction can be described several ways:
#1. In a sentence every item is a word
Copper reacts with chlorine to form copper (II) chloride.
#2. In a word equation some symbols used
Copper + chlorine ® copper (II) chloride

16. #3. The Skeleton Equation
Uses formulas and symbols to describe a reaction
but doesn’t indicate how many; this means they are NOT balanced
All chemical equations are a description of the reaction.

17. Write a skeleton equation for:
Solid iron (III) sulfide reacts with gaseous hydrogen chloride to form iron (III) chloride and hydrogen sulfide gas.
Nitric acid dissolved in water reacts with solid sodium carbonate to form liquid water and carbon dioxide gas and sodium nitrate dissolved in water.

18. Now, read these equations:
Fe(s) + O2(g) ® Fe2O3(s)
Cu(s) + AgNO3(aq) ® Ag(s) + Cu(NO3)2(aq)
NO2(g) N2(g) + O2(g)

19. #4. Balanced Chemical Equations
Atoms can’t be created or destroyed in an ordinary reaction:
All the atoms we start with we must end up with (meaning: balanced!)
A balanced equation has the same number of each element on both sides of the equation.

20. Rules for balancing:
Assemble the correct formulas for all the reactants and products, using “+” and “→”
Count the number of atoms of each type appearing on both sides
Balance the elements one at a time by adding coefficients (the numbers in front) where you need more - save balancing the H and O until LAST!
Double-Check to make sure it is balanced.

21. Never
Never change a subscript to balance an equation (You can only change coefficients)
If you change the subscript (formula) you are describing a different chemical.
H2O is a different compound than H2O2
Never put a coefficient in the middle of a formula; they must go only in the front
2NaCl is okay, but Na2Cl is not.

22. Video
Before you go through these notes, watch the following videos for how to balance an equation.
How to Balance a Chemical Equation OR
Mrs. Harmison's Balancing Equations Video 1

23. Nitrogen + hydrogen ammonia
Balancing Equations
N2 + H NH3
Nitrogen + hydrogen ammonia
Count atoms.
Reactants: 2 atoms N and 2 atoms H
Products: 1 atom N and 3 atoms of NH3

24. Balancing Equations N2 + H2 2NH3 Nothing is balanced.
Balance the nitrogen first by placing a coefficient of 2 in front of the NH3.
N2 + H NH3

25. Balancing Equations N2 + 3H2 2NH3 Hydrogen is not balanced.
Place a 3 in front of H2.
Reactant side: 2 atoms N, 6 atoms H
Product side: 2 atoms N, 6 atoms H
N H NH3

26. Balancing Equations Ca3(PO4)2 + H2SO4 CaSO4 + H3PO4
Count atoms in the reactant:
Ca – 3 atoms, P – 2 atoms, O – 8 atoms; H – atoms, S – 1 atom, O – 4 atoms

27. Balancing Equations Side note on Ca3(PO4)2
The subscript after the phosphate indicates two phosphate groups.
This means two PO43- groups with two P and eight O atoms.

28. Balancing Equations Ca3(PO4)2 + H2SO4 CaSO4 + H3PO4
Count atoms in the product.
Ca atoms – 1, S atom – 1, O atoms – 4; H atoms – 3, P atom – 1, O atoms – 4

29. Balancing Equations Ca3(PO4)2 + H2SO4 CaSO4 + H3PO4
In this equation, the ion groups do not break up.
Instead of counting individual atoms, ion groups may be counted.

30. Balancing Equations Ca3(PO4)2 + H2SO4 CaSO4 + H3PO4
Reactants: Ca2+ – 3, PO , H+ – 2, SO
Products: Ca2+ - 1, SO , H+ - 3, PO

31. Balancing Equations Ca3(PO4)2 + H2SO4 3CaSO4 + H3PO4
Balance the metal first by placing a coefficient of 3 in front of CaSO4.
Products: Ca – 3 atoms, SO groups
Ca3(PO4)2 + H2SO CaSO4 + H3PO4

32. Balancing Equations Ca3(PO4)2 + 3H2SO4 3CaSO4 + H3PO4
Three sulfate groups are needed on the reactant side so place a coefficient of 3 in front of H2SO4.
3H2SO4 gives 6 H+ and 3 SO42-.
Neither phosphate nor calcium is balanced.
Ca3(PO4) H2SO CaSO4 + H3PO4

33. Balancing Equations Ca3(PO4)2 + 3H2SO4 3CaSO4 + 2H3PO4
A coefficient of 2 placed in front of H3PO4 which balances both hydrogen and phosphate.
Ca3(PO4) H2SO CaSO H3PO4

34. Balancing Equations Balancing hints: Balance the metals first.
Balance the ion groups next.
Balance the other atoms.
Save the non ion group oxygen and hydrogen until the end.

35. Practice Balancing Examples
_AgNO3 + _Cu ® _Cu(NO3)2 + _Ag
_Mg + _N2 ® _Mg3N2
_P + _O2 ® _P4O10
_Na + _H2O ® _H2 + _NaOH
_CH4 + _O2 ® _CO2 + _H2O 2 2 3 4 5 2 2 2 2 2

36. Practice Balancing Examples
Check out these links to get more practice for Balancing Equations.

37. Review Video’s
If you’re still having trouble Balancing Equations, here are some tips from Chemguy. 
How - to:
Combustion:
Single Replacement:
Double Replacement:

38. The student will: SWBAT’s
Define five of the most common reaction types (synthesis/combination, decomposition, single-replacement, double displacement, and combustion).
Given a set of reactants and products, classify the reaction for five common reaction types.
Given the reactants, predict the anticipated products for the 5 basic forms of reaction types. (Example: for a basic decomposition reaction, the reactant is a binary ionic compound.)
Conduct multiple double-displacement chemical reactions in the qualitative analysis lab.
Perform the qualitative analysis lab. Using the observations from this lab, determine the identity of several unknown ionic compounds during a lab test.

39. The student will: SWBAT’s
Determine whether a single replacement reaction will occur based on a given set of reactants and the activity series. If a reaction occurs, predict the products that would be expected to form.
Use solubility rules to determine whether a given ionic compound is soluble or insoluble in water.
Given two ionic compounds as reactants, determine the substances anticipated to form and the physical state of each substance.
Describe a chemical reaction in different ways including using words and symbolic forms.
Describe how the law of conservation of mass is satisfied by balancing a chemical reaction.
Given a skeleton reaction, balance it by adding coefficients.