Chapter 8 Notes, Part I

1
Chapter 8 Notes, Part I

• Parts of an equation
• Types of reactions

2
What is a chemical reaction?

• A chemical reaction is the act of changing
  substances into new substances with new and
  different chemical and physical properties.

3
A Chemical Equation

• A chemical equation shows what is going on in a
  chemical reaction.
• Instead of writing down the entire sentence
  hydrogen reacts with oxygen to form dihydrogen
  monoxide (water), you could write

4
2H2 O2a2H2O
5
2H2 O2a2H2O
6
2H2 O2a2H2O
The arrow reads as produces, yields or
reacts to form
7
Iron reacts with oxygen gas to produce iron (III)
oxide
4Fe 3O2a2Fe2O3
8
Other symbols in an Equation

• (s) substance is solid
• (l) substance is liquid
• (g) substance is a gas
• (aq) substance is dissolved in water
• D heat

9
Other symbols in an Equation

• (A formula written above or below an arrow means
  it is a catalyst (a substance that speeds up a
  reaction without being used up by it.)

10
What is

• The name of something that speeds a reaction, but
  is not used up?
• The name of what you have before a reaction takes
  place?
• The symbol for heat?
• The number that shows there are more than one of
  the entire compound?

11
Types of reactions

• There are five types of reactions
• Combination
• Decomposition
• Single replacement
• Double replacement
• Combustion

12
Combination Reaction

• A combination reaction occurs when two or more
  elements or compounds combine to form a single
  substance.
• It will follow the form A B a AB
• Example Fe S aFeS

13
Decomposition Reaction

• A decomposition reaction occurs when one
  substance breaks down into two or more
  substances.
• It will follow the pattern
• AB a A B
• Example CaCO3aCaOCO2

14
Single Replacement Reaction

• One element replaces another element in a
  compound.
• Generally follows the formula
• AB C a A BC
• Example
• MgZn(NO3)2aZnMg(NO3)2

15
Double Replacement Reaction

• The exchange of two positive ions between two
  reacting compounds, forming two new compounds as
  a product.
• Generally follows the formula
• AB CD a AD CB
• Example
• Na2SCd(NO3)2aCdS2NaNO3

16
Combustion Reaction

• A compound reacts with oxygen to producing energy
  as heat and light.
• Most of the time, it is a hydrocarbon reacting
  with oxygen, and the outcome is always carbon
  dioxide and water
• Follows the form A O2 a CO2 H2O
• Example CH4 O2 a CO2 2H2O

17
What type of reaction is

• NaCN H2SO4 a 2HCN Na2SO4
• Zn 2HCl a ZnCl2 H2
• 2C2H6 7O2 a 4CO2 6H2O
• 2H2 O2 a 2H2O

18
ON THE WHITEBOARDS

• Tell which of the five types of reactions the
  following are

19
2Na 2H2O a 2NaOH H2

• Single replacement

20
Fe S a FeS

• combination

21
Al(OH)3 3NaCl a AlCl3 3NaOH

• Double replacement

22
CH4 2O2 a CO2 2H2O

• combustion

23
KClO2 a KCl O2

• decomposition

24
NaOH HCl a NaCl H2O

• Double replacement

25
4Fe 3O2 a 2Fe2O3

• combination

26
2C2H2 5O2 a 4CO2 2H2O

• combustion

27
H2 Cl2 a 2HCl

• combination

28
MgO 2KF a MgF2 K2O

• Double replacement

29
Na Al(NO3)3aNaNO3 Al

• Single replacement

30
2PbO2 a 2PbO 3O2

• decomposition

31
Ba(CN)2 H2SO4 a BaSO4 HCN

• Double replacement

32
C3H8 5O2 a 3CO2 4H2O

• combustion

33
4Li O2 a 2Li2O

• combination

34
2Ag 2HCl a 2AgCl H2

• Single replacement

35
2H2O2 a 2H2O O2

• decomposition

36
C2H2 O2 a CO2 H2O

• combustion

37
2HBr a H2 Br2

• decomposition

38
CrSO4 2AgNO3 a Cr(NO3)2 Ag2SO4

• Double replacement