Title: Balancing Chemical Equations
1Chapter 7
- Balancing Chemical Equations
2Chemical Reaction
- Describes chemical reaction.
- Chemical equation reactants yield products
Catalyst substance that speeds up a reaction
without being used up.
3Symbols Used
- (s) solid
- (l) liquid
- (g) gas
- (aq) aqueous (in water solution)
- gas as a product
- ppt. (precipitate)
- D means with heat
- Pt means with Platinum catalyst
4Balancing Chemical Equations
- Balanced equations have the same of atoms of
each element on each side of the equation. - Law of Conservation of Mass atoms can neither
be created nor destroyed, simply rearranged.
5Rules for Balancing Equations
- Get the correct formulas for reactants and
products. - Write reactants on left, products on right and
use plus signs and arrows when needed. - Count the of atoms of each element in reactants
and products.(Polyatomic ions on both sides count
as one.) - Balance of each element using coefficients.
- Coefficient whole in front of a formula.
6Rules for Balancing Equations
- Check each element to make sure equation is
balanced. - Make sure all coefficients are in the lowest
whole number ratio.
Do not change subscripts!!!
7Diatomic Molecules
- Diatomic Molecules- a molecule made up two atoms
of the same element. They are only diatomic when
they are alone.
- There are 7 naturally occurring
- diatomic molecules.
H O N Cl Br I F
85 Types of Reactions - 1
- Combination Reaction elements combine to form a
compound. - A B AB
9Examples of Combination Reactions
1. 2 Na Cl2 2 NaCl
2
2. Cu S Cu2S
3. SO3 H2O
H2SO4
4. CaO H2O
Ca(OH)2
2
MgO
5. Mg O2
2
105 Types of Reactions - 2
- Decomposition Reaction elements break down into
its element. - AB A B
11Examples of Decomposition Reactions
1. 2 NaCl 2 Na Cl2
2
2
2. H2O H2 O2
2
3. HgO
Hg O2
2
Challenge Copper I Chloride Decomposes
2CuCl 2Cu Cl2
125 Types of Reactions - 3
- Single Replacement Reaction one element
replaces another element in a compound. - AB C A CB
- or
- AB D AD B
-
-
- -
- -
13Reactivity Series of Metals and Non-Metals
- The single metallic element will only replace the
metal in a compound if it is more reactive. - A chart is used to determine if the lone metal is
more reactive. If not, no reaction occurs. - The single non-metallic element will only replace
the non-metal in a compound if it is more
reactive. The higher up in the group the
non-metal is, the more reactive it is.
14Examples of Single Replacement Reactions
1. Zn H2SO4 ZnSO4 H2
2. K HOH KOH H2
NaCl Br2
2
2
3. Cl2 NaBr
155 Types of Reactions - 4
- Double Replacement Reaction two compounds react
and exchange positive ions to form two new
compounds. - AB CD AD CB
-
- -
- -
16Examples of Double Replacement Reactions
1. NaOH H2SO4 Na2SO4 HOH
2
2
2. BaCl2 K2CO3 BaCO3 KCl
2
3. FeS HCl
2
H2S FeCl2
175 Types of Reactions - 5
- Combustion Reaction oxygen reacts with a
compound composed of C and H. - CxHy O2 CO2 H20
Also called Burning (exothermic) The products are
always CO2 and H2O.
18Examples of Combustion Reactions
1. C6H6 O2 CO2
H2O
3
6
7½
C6H6 O2 CO2 H2O
2 15 12
6
2. CH3OH O2 CO2 H2O
2
1½
CH3OH O2 CO2 H2O
2 3 2
4
19Special Decomposition Reactions 1
- Decomposition of a Carbonate
- XCO3 XO CO2
-
-
20Special Decomposition Reactions 2
- Decomposition of a Hydroxide
- XOH XO H2O
-
-
21Special Decomposition Reactions 3
- Decomposition of a Chlorate
- XClO3 XCl O2
-
-
22Special Decomposition Reactions 4
- Special single Replacement Reaction
- Group IA or IIA metal and H2O
-
- X HOH XOH H2
-
-
23How to ID types of reactions.
- Combination Reactions given 2 items that form 1
new compound. - Decomposition Reactions given a single compound
that breaks into parts. - Single Replacement given a single element plus
a single compound, forms a new compound a a
different element. - Double Replacement given two compounds (s or
s change places). - Combustion Reaction given CH compound with
Oxygen, always forms water and carbon dioxide.
24The End