1. Chapter 7
Chemical Reactions

2. 7-1 Describing Reactions
In a chemical __________, the substances that undergo change are called ___________
The new substances formed as a result of that change are called ___________
_________  ____________
Ex. Carbon + oxygen  carbon dioxide
________ equation

3. Chemical equations Ex. C + O2  CO2 Chemical _________
A chemical __________ is a representation of a chemical reaction in which the reactants and products are expressed as ____________

4. Conservation of Mass
During chemical reactions, the________ of the products is always_______ to the mass of the reactants.
Established by Antoine Lavoisier and is known as the_____________________
The law of conservation of mass states that mass is neither _________ nor __________ in a chemical reaction

5. How is mass conserved in chemical change? Activity
Follow the directions on page 191 in your book
Fill out following information
Mass of the bag and the water=____________
Mass of a square piece of paper with sides 10cm__________________
Mass of the tablet and the paper together____________
Mass of just the tablet_______________
The combined masses of the bag, the water, and the tablet___________
Mass of the bag and its contents_____________

6. Activity questions
How do you know whether a chemical change took place?

7. Activity Question
What happened to the mass of the plastic bag and its contents after the bubbling stopped?
What might this information tell you about a chemical change?

8. Balancing Equations 7-1 Continued
In order to show that mass is conserved during a reaction, a chemical equation must be _________
You can balance a chemical equation by changing the_________, the numbers that appear _________ the formulas
As you balance equations, you should never change the ___________ in a formula

9. Steps to balancing equations
Count the _________ of atoms of each element on each side of the equation
Ex: N2H4 + O2  N2 + H2O
Left side has ____ nitrogen,____hydrogen, and ______ oxygen atoms
The right side has ____nitrogen,_____hydrogen, and____oxygen atom
The hydrogen and oxygen atoms need to be_______.

10. Steps to balancing equations
6. Change one or more coefficients until the equation is balanced
_1_N2H4 + _1_O2  _1_N2 + _2_H2O
The equation is now balanced
Each side has _____ nitrogen,_____ oxygen, and _______ hydrogen atoms

11. Practice Balancing equations problems
___Na + ___H2O ____NaOH + ___H2
___HCl + ___CaCO3  ____CaCl2 +___CO2 + ____H2O
____Al + ____Cl2  _____AlCl3
___Cu + _____O2  _____CuO
____H2O2  ____H2O + ____O2

12. What is a MOLE? It is a number of things….. - Just like a dozen
1 dozen eggs = 12 eggs
So, instead of 12 the mole is equal to 602 billion trillion
– OR-
6.02 x 1023

13. Just How Big is a Mole? 6.02 X1023 Pennies:
Would make at least 7 stacks that would reach the moon.

14. How Big is a mole?
Cover the earth to a depth of 200 miles with soft drink cans.
Cover the USA to a depth of 9
miles of unpopped popcorn
kernels.

15. The mole is many things….
1 dozen cookies = 12 cookies
1 mole of cookies = 6.02 x 1023 cookies
1 dozen cars = 12 cars
1 mole of cars = 6.02 x 1023 cars
1 dozen Al atoms = 12 Al atoms
1 mole of Al atoms = 6.02 x 1023 atoms
NOTE: the mole is abbreviated mol (gee, that’s a lot quicker to write……)

16. Molar Mass Mass of 1 ______ of a pure substance
Numerically equal to the atomic mass but expressed in _______
The atomic mass of carbon is 12.0____, so the molar mass of carbon is 12.0_____

17. What is the molar mass of the following:
Potassium ?
Nickel ?

18. What is the atomic mass of the following:
Potassium ?
Nickel ?

19. Practice
What is the molar mass of the following:
KCl
C2H6
CaCO3
H2O

20. Homework/More Practice
What is the molar mass of the following:
HCl
NaCl
CaO

21. Homework/More Practice
Balance the following
___Na + ____H2O ___H2 + ___NaOH
___C2H6 + ____O2  ___CO2 + ___H2O

22. Beaker Breaker
Calculate the molar mass of the following:
MgCl2
CaBr2

23. Gram- Mole Conversions

24. How many grams are needed to have 0.852 moles gold?
0.852 mol Au g Au
mol Au
= ______g Au

25. Convert 2.50moles of KClO3 to grams

26. Calculate how many grams are in 0.700moles of H2O2?

27. How many moles are in 55 g of lead?
g Pb mol Pb
g Pb
= _______moles Pb

28. How many moles are in 86.1 g sodium?
86.1 g ? mole Na =
? g
86.1 g mole Na = g
_______moles Na

29. How many moles are in 22 grams of copper metal?

30. 7-2 Types of Reactions General types of chemical reactions
______________

31. Single Replacement
________________ reaction is a reaction in which one element takes place of another element in a compound.
A + BC  B + AC

32. Teacher Demonstration
See handout
Cu + 2AgNO3 2Ag + Cu(NO3)2
Copper replaces the silver nitrate to form copper(II) nitrate
The products is_______, which you can see. The other product is_____________, gives the solution its blue color.

33. 7-2 Continued Reactions as Electron Transfer
The discovery of subatomic particles enabled scientists to classify certain chemical reactions as transfers of_______________ between atoms.
A reaction in which electrons are transferred from one reactant to another is called an ____________________ reaction, _________ reaction

34. Oxidation
Synthesis reactions, in which a____________combines with__________, traditionally have been classified as oxidations.
2Ca +O2  2_________
Ca  Ca+2 + 2e-
Calcium ________ two electrons
A reactant is_________ if it loses electrons

35. Reduction
As calcium atoms lose electrons during the synthesis of calcium oxide, the oxygen________ electrons
O + 2e-  O2-
The process in which an element gains electrons during a chemical reaction is called____________
A reactant is said to be______________ if it gains electrons.
Oxidation and reduction always occur________.

36. Beaker Breaker
Identify the following reactions as either synthesis, decomposition, single replacement, double replacement, or combustion:
2C2H6 + 7O2  4CO2 + 6H2O
Ca + 2HCl  CaCl2 + H2

37. Beaker Breaker Cont.
Write a paragraph explaining why the formation of water can be classified as a synthesis or combustion.

38. 7-3 Energy Changes in Reactions Chemical Bonds and Energy
Heat produced by a_________(C3H8) grill is a form of energy
Balance equation:
C3H8 + ____O2 ___CO2 +___H2O
_________ will be added to the right side of the equation

39. Propane Combustion using models
C3H8 + 5O2  3CO2 + 4H2O
Open to page 207 follow Figure 17

40. Chemical Energy
_____________ is the energy stored in the chemical bonds of a substance.
Using the models to make
C3H8 (propane)
How many C-H bonds_________
How many C-C bonds_________

41. Chemical Bonds
Chemical _________ involve the________ of chemical bonds in the __________ and the_______ of chemical bonds in the ________.
Each propane molecule reacts with_______ oxygen molecules.
In order for the reaction to occur, the ____ C-H single bonds, _____ C-C single bonds and____O=O double bonds must be broken.
Breaking bonds require energy
Propane grills require a igniter to provide enough energy to ________the bonds

42. Chemical Bonds
After the reaction of propane (it is burned) occurs, ______molecules of carbon dioxide (CO2) and ______ molecules of water (H2O) are formed.
There is _____ C=O double bonds and ____ O-H single bonds formed as the ________.
Forming bonds__________ energy
________and ________ given off by a propane stove are the results from the formation of the new chemical bonds

43. Homework
Section 7-2 Review
#1 , 3, 4, 5

44. Beaker Breaker
Identify the following reactions as either single displacement, double displacement, decomposition, synthesis, or combustion
NaCl + H2SO4  K2SO4 + H2O
CaO + CO2  CaCO3
MgCl2  Mg + Cl2

45. 7-3 Continued Exothermic and Endothermic Reactions
During a chemical reaction, energy is either ________ or ___________
A chemical reaction that_________ energy to its surroundings is called an_____________ reaction
Ex: Freezing
A chemical reaction that__________ energy from its surroundings is called an____________
Ex: Melting

46. Exothermic Reactions
In exothermic reactions, the energy released as the products form is __________ than the energy required to break the bonds in the reactants
Example – Combustion
C3H8 + 5O2  3CO2 + 4H2O kJ

47. Endothermic Reactions
In an endothermic reaction, more energy is required to___________ the bonds in the reactants than is released by the formation of the products.
Example: The decomposition of mercury (II) oxide
2HgO kJ  2Hg + O2

48. Conservation of Energy
The law of____________________ states in exothermic and endothermic reactions the total amount of energy before and after the reaction is the same.

49. Homework
7-3 Section Review page 209
Numbers 1,2,3

50. Ticket Out the Door
Please explain in a few sentences how melting is an example of an endothermic reaction

51. 7-4 Reaction Rates
A ________________ is the rate at which reactants change into products over time.
Reaction rates tell you how_______ a reaction is going

52. Factors Affecting Reaction Rates
Factors that affect reaction rates include:
___________,
_____________,
_____________
______________
Involve ___________ between particles
Reaction rate depends on how often these particles _________

53. Temperature An_________ in temperature will _________the reaction rate
Ex. Frying an egg
________ the temp will ________ the reaction rate.
Ex: refrigerating milk to prevent spoiling
Increasing the ________, increases the number of collisions between the particles, then _________ increases

54. Surface Area
The ________ the particle size of a given mass, the _______ is its surface area.
An increase in _________ increases the __________ of reactants to one another.
The __________this exposure, the more collisions there are that involve reacting particles.
________ the surface area of a reactant tends to__________ the reaction rate.

55. Beaker Breaker
A__________rate is the rate at which reactants change into products over time
List two factors that affect reaction rates:
An __________ in temperature will_________ the reaction rate

56. Stirring
You can ____________ the exposure of reactants to each other by _________
Ex: washing machine
Stirring _____________ the reaction.
____________ between the particles of the reactants are more likely to happen

57. Concentration
_____________ refers to the number of particles in a given volume
Ex: concentrated dyes
The reaction rate is ___________
For gases, concentration changes with_______________ of a gaseous reactant, the __________ is its concentration, and the_________ the reaction rate.

58. Catalysts
A ___________ is a substance that affects the reaction rate without being used up in the reaction.
Chemists use catalysts to____________ a reaction or enable a reaction to occur at ___________ temperatures.
Since the catalyst is neither a reactant nor a product, it is written ________ the arrow.

59. 7-5 Equilibrium
_____________ is a state in which the forward and reverse paths of change can take place at the ________ rate.
Recall that changes to matter are either physical or chemical.
When ___________ chemical changes take place at the same rate, a chemical equilibrium is reached

60. Physical Equilibrium
When a __________ change does not go to completion, a physical equilibrium is established between the forward and reverse changes
Ex: H2O (l) H2O(g)
_________and___________are both physical changes

61. Chemical Equilibrium
A ___________ reaction is a reaction in which the conversion of reactants into products and the conversion of products into reactants can happen simultaneously
When a chemical reaction does not go to completion, a ________________ is established between the forward and reverse reactions.
Ex: 2SO2 (g) + O SO3 (g)
Synthesis and decomposition

62. Factors Affecting Chemical Equilibrium
When a change is introduced to a system in equilibrium, the equilibrium shifts in the direction that ________ the change.
Principle was created by__________________
Ex: N2 + 3H NH3 + Heat

63. Temperature N2 + 3H2 2NH3 + Heat
Synthesis of ammonia, heat is written as a product
Forward reaction is ___________
Reverse is decomposition and is ____________
Adding heat would then favor the______________reaction, which is endothermic

64. Pressure
__________ the pressure of the system, equilibrium would shift in the direction that __________ the pressure of the system.
Decreasing the pressure, the system would favor the reaction that produces__________gas molecules.
Left Side has 4 gas molecules and right side has 2, so equilibrium would shift to the ________ when increasing the pressure

65. Concentration
Removing ammonia from the system, Le Chatelier’s principle says that the equilibrium would shift in the direction that_________ ammonia
In order to produce ammonia, the system would favor the __________reaction

66. Complete the following
Page 219 # 1,2,3,4, 5,