1. Chemistry Chapter 8 Chemical Equations
Balancing Formula Equations

2. What is a Chemical Reaction?
A chemical reaction occurs when two or more substances are changed into different substances.

3. What is a Chemical Equation
What is a Chemical Equation? A chemical equation represents, with symbols and formulas, the identities and relative molecular or molar amounts of the reactants and products in a chemical reaction.

4. Indications of a Chemical Reaction
Evolution of energy as heat and light.
Production of a gas.
Formation of a precipitate.
Color change.

5. Characteristics of Chemical Equations
The equation must represent known facts.
The equation MUST contain the correct formulas for the reactants and products.
The Law of Conservation of Mass must be satisfied. We can use coefficients to satisfy this law.
*coefficients- a small whole number that appears in front of a formula in a chemical equation

6. Word & Formula Equations
word equation- an equation in which the reactants and products of a reaction are represented by words
formula equation- represents the reactants and products of a chemical reaction by their symbols & formulas
balanced formula equation- uses coefficients to allow conservation of mass

7. Examples of the Types of Equations
word equation-
iron II phosphate reacts with aluminum nitrate to produce iron II nitrate and aluminum phosphate
formula equation-
Fe3(PO4)2 + Al(NO3)3  Fe(NO3)2 + AlPO4
balanced formula equation-
Fe3(PO4)2 + 2 Al(NO3)3  3 Fe(NO3)2 + 2 AlPO4

8. Symbols Used in Chemical Equations
 yields
(s) solid
(l) liquid
(aq) aqueous
(g) gas

9. Diatomic Elements
There are seven common elements that are called the “diatomic elements”. Whenever they are pure elements and appear alone (NOT in a compound) in an equation, their symbol contains two atoms rather than one. They include:
hydrogen (H2) oxygen (O2) nitrogen (N2) fluorine (F2) chlorine (Cl2) bromine (Br2)
iodine (I2)
A simple mnemonic is “halogens HON”.

10. Practice Problems
Do practice problems #1, #2, & #3 on page 268 of the textbook.

11. Practice Problem 1 page 268
1a) Ca (s) + S (s)  CaS (s) already balanced 1b) H2 (g) + F2 (g)  HF (g) H2 (g) + F2 (g)  2 HF (g) balanced 1c) Al (S) + ZnCl2 (aq)  Zn (s) + AlCl3 (aq) 2 Al(S) + 3 ZnCl2 (aq)  3 Zn(s) + 2 AlCl3(aq)

12. Practice Problem #2 page 268
2a) CS2(l) + O2(g)  CO2(g) + SO2(g) liquid carbon disulfide reacts with oxygen gas to produce carbon dioxide gas and sulfur dioxide gas 2b) NaCl(aq) + AgNO3(aq)  NaNO3(aq) + AgCl(s) aqueous sodium chloride reacts with aqueous silver nitrate to yield aqueous sodium nitrate and solid silver chloride

13. Practice problem #3 page 268
N2H4 + O2  N2 (g) + H2O
N2H4 + O2  N2 (g) + 2 H2O

14. Significance of a Chemical Equation
The coefficients of a chemical reaction indicate relative, not absolute, amounts of reactants and products.
The relative masses of the reactants and products of a chemical reaction can be determined from the reaction’s coefficients.
The reverse reaction for a chemical equation has the same relative amounts of substances as the forward reaction.

15. Rules for Balancing Chemical Equations
Identify the names of the reactants and products and write a word equation.
Write a formula equation by substituting correct formulas for the names of the reactants and products.
Using coefficients, balance the formula equation according to the law of conservation of mass.
Balance the different types of atoms one at a time.
First balance atoms of elements that appear only once on each side.
Balance polyatomic ions that appear on both sides as single units.
Balance H and O atoms after atoms of other elements have been balanced.
Count atoms to be sure the equation is balanced.

16. Balancing a Formula Equation
hydrogen gas reacts with chlorine gas to produce hydrogen chloride gas
_?_ H2(g) + _?_ Cl2(g)  _?_ HCl(g)
H2(g) Cl2(g)  2 HCl(g)

17. Practice #1- Balance the following formula equations.
__CaF2 + __Na2S  __CaS + __ NaF __FeS + __ AlPO4  __Fe3(PO4)2 + __Al2S3 __Na + __Cl2  __NaCl __H2 + __O2  __H2O __C2H4 + __O2  __CO2 + __H2O __HBr + __NaOH  __NaBr + __H2O __Na2SO4 + __AlPO4  __Na3PO4 + __Al2(SO4)3 __N2 + __O2  __N3O7 __FePO4 + __CaSO4  __Fe2(SO4)3 + __Ca3(PO4)2 __CuBr2 + __NaF  __CuF2 + __NaBr

18. Balanced Formula Equation
__CaF2 + __Na2S  __CaS + __ NaF
CaF2 + Na2S  CaS + 2 NaF 1:1:1:2
__FeS + __ AlPO4  __Fe3(PO4)2 + __Al2S3
3 FeS + 2 AlPO4  Fe3(PO4)2 + Al2S3 3:2:1:1
__Na + __Cl2  __NaCl
2 Na + Cl2  2 NaCl 2:1:2
__H2 + __O2  __H2O
2 H2 + O2  2 H2O 2:1:2
__C2H4 + __O2  __CO2 + __H2O
C2H4 + 3 O2  2 CO2 + 2 H2O 1:3:2:2

19. Practice __HBr + __NaOH  __NaBr + __H2O
__Na2SO4 + __AlPO4  __Na3PO4 + __Al2(SO4)3
3 Na2SO4 + 2 AlPO4  2 Na3PO4 + Al2(SO4)3 3:2:2:1
__N2 + __O2  __N3O7
3 N2 + 7 O2  2 N3O7 3:7:2
__FePO4 + __CaSO4  __Fe2(SO4)3 + __Ca3(PO4)2
2 FePO4 + 3 CaSO4  Fe2(SO4)3 + Ca3(PO4)2 2:3:1:1
__CuBr2 + __NaF  __CuF2 + __NaBr
CuBr2 + 2 NaF  CuF2 + 2 NaBr 1:2:1:2

20. Practice Problems
Do the following practice problems from the textbook:
practice #1 & #2 on page 272
practice #1 (a, b, c) on page 274
section review #2, #3, #4, & #5 on
page 274

21. Practice Problems page 272
1a) Mg + HCl  MgCl2 + H2
Mg + 2 HCl  MgCl2 + H2
1b) HNO3 (aq) + Mg(OH)2 (s)  Mg(NO3)2 (aq) + H2O (l)
2 HNO3 (aq) + Mg(OH)2 (s)  Mg(NO3)2 (aq) + 2 H2O (l)
2) Ca(s) + H2O(l)  Ca(OH)2 (aq) + H2 (g)
Ca(s) + 2 H2O(l)  Ca(OH)2 (aq) + H2 (g)

22. Practice Problems page 274
1a) Na (s) + Cl2 (g)  NaCl (s)
2 Na (s) + Cl2 (g)  2 NaCl (s)
1b) Cu (s) + AgNO3 (aq)  Cu(NO3)2 (aq) + Ag (s)
Cu (s) + 2 AgNO3 (aq)  Cu(NO3)2 (aq) + 2 Ag (s)
1c) Fe2O3 (s) + CO (g)  Fe (s) + CO2 (g)
Fe2O3 (s) + 3 CO (g)  2 Fe (s) + 3 CO2 (g)

23. Section Review page 274
2) H2SO4 (aq) + NaOH (aq)  Na2SO4 (aq) + H2O (l)
H2SO4 (aq) + 2 NaOH (aq)  Na2SO4 (aq) + 2 H2O (l)
3a) solid potassium plus liquid water produce aqueous potassium hydroxide and hydrogen gas
3b) solid iron metal plus chlorine gas yields
solid iron (III) chloride
4) H2S (g) + O2 (g)  SO2 (g) + H2O (g)
2 H2S (g) + 3 O2 (g)  2 SO2 (g) + 2 H2O (g)

24. Section Review page 274
5) VO + Fe2O3  V2O5 + FeO 2 VO + 3 Fe2O3  V2O5 + 6 FeO

25. QUIZ #1- Balancing chemical equations
Balance the following formula equations. 1- ___C3H8 + ___O2  ___CO2 + ___H2O 2- ___Al2(SO4)3 + ___Fe3(PO4)2  ___AlPO4 + ___FeSO4 3- ___Na + ___Cl2  ___NaCl 4- ___N2 + ___O2  ___N3O7 5- ___NaNO3 + ___Al2(CO3)3  ___Na2CO3 + ___Al(NO3)3

26. Types of Chemical Reactions
synthesis reaction- also known as a composition reaction, two or more substances combine to form a new compound.
A + X  AX
Could be called the ”Boy Meets Girl” reaction.

27. Types of Chemical Reactions
decomposition reaction- a single compound undergoes a reaction that produces two or more simpler substances.
AX  A + X
The “Boy Loses Girl” reaction.

28. Types of Chemical Reactions
single-displacement reaction- also known as a replacement reaction, one element replaces a similar element in a compound.
A + BX  AX + B
The “Boy Loses Girl to Best Friend” reaction.

29. Types of Chemical Reactions
double-displacement reaction- also known as a double replacement reaction, the ions of two compounds exchange places in an aqueous solution to form two new compounds.
AX + BY  AY + BX
The “Best Friends Trade Girlfriends” Reaction.

30. Types of Chemical Reactions
combustion reaction- a substance combines with oxygen, releasing a large amount of energy in the form of light and heat
A + O2  AO + fire
The “Where There’s Smoke There’s Fire” reaction.

31. Reaction Types Summary
Synthesis A + X  AX Decomposition AX  A + X Single Displacement A + BX  AX + B Double Replacement AX + BY  AY + BX Combustion A + O2  AO + fire

32. QUIZ #2- Balance the following formula equations then identify the reaction type.
__Na + __Br2  __NaBr
reaction type=
__Fe2O3  __Fe + __O2
__CuI + __F2  __CuF + __I2
__FeSO4 + __Ca3(PO4)2  __Fe3(PO4)2 + __CaSO4
__C4H8 + __O2  __CO2 + __H2O (fire)

33. synthesis (composition) __Fe2O3  __Fe + __O2 2 Fe2O3  4 Fe + 3 O2
QUIZ # Balance the following formula equations then identify the reaction type.
__Na + __Br2  __NaBr
2 Na + Br2  2 NaBr
synthesis (composition)
__Fe2O3  __Fe + __O2
2 Fe2O3  4 Fe + 3 O2
decomposition
__CuI + __F2  __CuF + __I2
2 CuI + F2  2 CuF + I2
single replacement (single displacement)
__FeSO4 + __Ca3(PO4)2  __Fe3(PO4)2 + __CaSO4
3 FeSO4 + Ca3(PO4)2  Fe3(PO4)2 + 3 CaSO4
double replacement (double displacement)
__C4H8 + __O2  __CO2 + __H2O (fire)
C4H8 + 6 O2  4 CO2 + 4 H2O (fire)
combustion

34. Types of Chemical Reactions
synthesis reaction- also known as a composition reaction, two or more substances combine to form a new compound.
A + X  AX

35. Journal Investigation- Synthesis Reaction
Get a strip of magnesium ribbon and an iron crucible from the front.
Roll the magnesium strip into a loose ball.
Weigh & record the mass of the magnesium & crucible on a scale.
Heat the crucible and magnesium using your burner until the magnesium begins to glow. Turn off the burner.
Allow the crucible to cool at least five minutes.
Weigh and record the new mass of the crucible & magnesium oxide product.
Add three or four drops of tap water to the crucible. Waft the gas produced to attempt to smell the odor of ammonia.

36. Safety Precautions
Burner & equipment become very hot. DO NOT touch. Handle with crucible tongs. Eye protection MUST be worn due to possible sparks in the crucible. Safety apron is to be worn to protect skin & clothing. Use a wafting technique when trying to detect ammonia smell. Rinse & dry the cool crucible after lab is finished.

37. Journal Investigation- Synthesis Reaction ANALYSIS
Using the recorded masses, show how this proves a synthesis reaction occurred.
The magnesium (Mg) combined with oxygen (O2) in the air to form a magnesium oxide (MgO) product. Write a balanced formula equation for this reaction.
When you added water, you should have smelled ammonia (NH3). The formula equation for this reaction would be Mg3N2 + H2O  Mg(OH)2 + NH3. Balance this formula equation.
Where did the nitrogen come from to form the Mg2N3 as another product of this synthesis reaction?

38. Types of Chemical Reactions
decomposition reaction- a single compound undergoes a reaction that produces two or more simpler substances.
AX  A + X

39. Lab Investigation- Decomposition Reaction
Get a test tube with 5 – 10 mL of fresh hydrogen peroxide (H2O2) from the rack in the front of the room.
Add a match-head size amount of manganese dioxide (MnO2) to the test tube to act as a catalyst (a substance that speeds up a reaction without becoming part of it).
Observe the hydrogen peroxide for signs of a chemical reaction.
While the reaction is still taking place, set the end of a wooden splint on fire then blow it out.
While the splint is still glowing, lower it into the top of the test tube without touching the liquid. Observe the result. You can repeat this step several times until the reaction in the test tube stops.

40. Lab Investigation- Decomposition Reaction ANALYSIS
Use your textbook to find the definition of a catalyst. Write the definition in the log.
What was the indication in the test tube that a chemical reaction was taking place?
Hydrogen peroxide decomposed into oxygen gas and liquid water. Write the balanced formula equation for this reaction.
What test was used to demonstrate that oxygen gas was a product of the reaction?
Write a balanced formula equation for the reaction between the carbon in the wood and the oxygen gas being produced. What type of chemical reaction is this?

41. Types of Chemical Reactions
single-displacement reaction- also known as a replacement reaction, one element replaces a similar element in a compound.
A + BX  AX + B

42. Lab Investigation- Single Replacement Reaction
Get a small beaker with mL. of silver nitrate (AgNO3). BE CAREFUL- silver nitrate will cause burn on your skin & clothing.
Record in your journal the color of the silver nitrate solution.
Get a penny from your instructor.
Gently lower the penny into the beaker of silver nitrate making sure there is no splash.
Record observation of the penny in your journal for 10 minutes at 1 minute intervals.
Use a piece of tape to identify your beaker & penny. Place the beaker in the fume hood overnight.
Record your observations after 24 hours. Be sure to include the color of the liquid in the beaker.

43. Lab Investigation- Single Replacement Reaction ANALYSIS
What were the indications that a chemical reaction had taken place?
What were the products of the single replacement reaction between copper (Cu) and silver nitrate (AgNO3)? (Assume the product contains the copper I ion.)
Write the balanced formula equation for the reaction between copper and silver nitrate.
Based on your observations, which element, copper or silver would appear higher on an activity series of metals? Why?

44. Types of Chemical Reactions
double-displacement reaction- also known as a double replacement reaction, the ions of two compounds exchange places in an aqueous solution to form two new compounds.
AX + BY  AY + BX

45. Lab Investigation- Double Replacement Reaction
Get a test tube with 5 mL. of silver nitrate (AgNO3). BE CAREFUL- silver nitrate will cause burns on your skin & clothing.
Record in your journal the color of the silver nitrate solution.
Get a test tube of sodium chloride (NaCl) solution. Record your observations of the solution.
Gently pour the sodium chloride into the test tube of silver nitrate making sure there is no splash.
Record your observation of the mixtures of the two aqueous solutions.
Take the test tubes to the front for disposal.

46. Lab Investigation- Double Replacement Reaction ANALYSIS
What were the indications that a chemical reaction had taken place?
What were the products of the double replacement reaction between sodium chloride (NaCl) and silver nitrate (AgNO3)?
Which of these products is the precipitate?
Write the balanced formula equation for the reaction between aqueous sodium chloride and aqueous silver nitrate.

47. Types of Chemical Reactions
combustion reaction- a substance combines with oxygen, releasing a large amount of energy in the form of light and heat
A + O2  AO + fire

48. Just for Fun- The Kandy Killer
This will be a demonstration ONLY.
We will be heating potassium chlorate (KClO3). This will cause it to undergo a decomposition reaction that produces potassium chloride and oxygen.
A glowing splint will be used to confirm that oxygen is being produced.
Candy will be dropped into the test tube. A rapid chemical reaction should be seen. YEA!!!

49. Practice Problems #1 through #5 on page 284 of the textbook.
section review problems:
#1 through #5 on page 284 of the textbook.

50. Section Review page 284
1- List 5 types of reactions identified in this chapter. synthesis decomposition single displacement (replacement) double displacement (replacement) combustion 2a- N2 + 3H2  2 NH3 synthesis b- 2Li + 2H2O  2LiOH + H2 single displacement c- 2NaNO3  2NaNO2 + O2 decomposition d- 2C6H O2  12CO2 + 14H2O combustion

51. 3a-

52. QUIZ #3- Chemistry Chapter 8 Test Review
Balance the following equations & identify the reaction type.
__Ca(NO3)2 + __Na3PO4  __Ca3(PO4)2 + __NaNO reaction type:
__C4H8 + __O2  __CO2 + __H2O + fire reaction type:
__H2 + __Br2  __HBr reaction type:
__K + __HBr  __KBr + __H2 reaction type:
__CaCO3  __CaO + __CO2 reaction type:

53. Activity Series of the Elements
The activity of an element describes how it can react under specific conditions
An activity series is a list of elements organized according to the ease with which elements undergo certain chemical reactions.

54. Activity Series of Metals
Most reactive: Li Rb React with cold water and acids, K replacing hydrogen. Ba React with oxygen forming oxides Sr Ca Na

55. Activity Series of Metals
2nd most reactive set: Mg Al React with steam (but not cold Mn water) and acids, replacing Zn hydrogen. React with oxygen, Cr forming oxides. Fe Cd

56. Activity Series of Metals
3rd most reactive set: Co Do not react with water. Ni React with acids, replacing hydrogen. Sn React with oxygen, forming oxides. Pb

57. Activity Series of Metals
4th most reactive set: H2 Sb React with oxygen, forming oxides. Bi Cu Hg

58. Activity Series of Metals
Least reactive set: Ag Fairly unreactive, forming oxides only Pt indirectly. Au

59. Activity of Halogen Non-metals
The following halogens will replace any other halogen below it in a single replacement reaction. F2 Cl2 Br2 I2

60. Practice Problems
Use table 3 on page 286 of the textbook to answer Practice Problems #1 through #3 on page 287.

61. Practice problems page 287
1a- ____ Cr + ____H2O (l)  ? cannot occur- Cr will not react with water, only steam b- ____Pt + ____O2  ? cannot occur-Pt does not form oxides directly c- ____Cd + 2 HBr  ? (HBr is an acid) can occur Cd reacts with acids to form hydrogen Cd + 2 HBr  CdBr2 + H2 d- ____Mg + ____H2O(g)  ? H2O (g) is steam can occur, Mg will react with steam to form hydrogen Mg(s) + 2 H2O(g)  Mg(OH)2 (aq) + H2 (g)

62. Practice Problems page 287
2- Identify the element that replaces hydrogen from acids but does not replace tin from its compounds. Lead (Pb) replaces hydrogen from acids, but is below tin (Sn) in the activity series so it cannot replace tin (Sn). 3- According to table 3, what is the most active transition metal? As you go down the activity series of metals, manganese (Mn) is the first transition metal in the list, so it is the most reactive transition metal.

63. QUIZ #4- Chemistry Chapter 8 Test Review
Use the activity series to determine if the following reactions are possible.
1) Sb + HCl (an acid)
2) K + ZnCl2 
3) 2 HF + Cl2 
4) 2 H2O (l) + 2 Na 
5) MgBr2 + Cl2 

64. Chemistry Chapter 8 Test
25 multiple choice questions:
definition of a precipitate
identify diatomic elements when used in chemical equations
rules for balancing equations
identify a word equation
symbols used in equations (eg. aq)
determine coefficients needed to balance equations
identify reaction types by definition & balanced formula equations
definitions of activity & activity series and how they are used

65. Honors Chemistry Chapter 8 Test
35 multiple choice questions:
chemical reactions & law of conservation of mass
indicators of chemical reactions
definition of a precipitate and symbols used in equations
identify a word equation & a formula equation
diatomic elements & how they are written in an equation
Identify coefficients needed to balance formula equations
rules for balancing formula equations
reaction types by definition & balanced equations
identifying & predicting products of reactions
definitions of activity & activity series
use activity series to predict products formed

66. Honors Chemistry Chapter 8 Test
1 short answer question:
When balancing a formula equation, why must the formula subscripts remain unchanged?
1 essay question:
Consider an equation. How does the equation violate the law of conservation of mass? How can the equation be rewritten to conform to the law of conservation of mass?
3 problems:
Write a balanced formula equation for a synthesis reaction when given the reactants & product.
Use an activity series to predict if a reaction can occur. If yes, write the balanced formula equation. (2 of these)