Download Chemical Equations

Chp.12/Activity #4
2/25/2015
Wednesday
Chemical Equations (p792)
Due Today:
HW. Number of atoms in a formula
Learning targets
•Represent chemical changes using word
equations and chemical equations.
•Use the principle of conservation of matter to
balance chemical reactions.
1.
2.
3.
4.
5.
6.
Carbon Monoxide
CCl4
Iron (III) Oxide
Al2(SO4)3
CuF2
Magnesium Sulfate
CO
Carbon Tetrachloride
Fe2O3
Aluminum Sulfate
Copper (II) Flouride
MgSO4
7. How does an ionic compound form? What forms the bond?
8. How does a covalent compound form? What forms the
bond?
Chemical Reactions and Equations
• The scientific word for chemical change is “Chemical
Reaction”
• Chemical Reactions are written in Chemical Equations.
• E.g. Zn + 2HCl -> ZnCl2 + H2 is a chemical equation.
• A Chemical Reaction involves the breaking/formation of
chemical bonds
• E.g. H-Cl bond is broken and H-H bond is newly formed.
Law of Conservation of Mass
• Matter is never created or destroyed.
• So the Total Mass of the Reactants and the Products need to be the
same.
Zn + 2HCl -> ZnCl2 + H2
• E.g.
Element
Reactants
Products
Zn
1
1
Cl
2
2
H
2
2
Both sides have the
same number and
kind of elements!
Balancing Chemical Equations
• You first need to be able to count the number of atoms.
• Coefficients (always whole numbers) tell us how many
compounds we have.
• E.g. 2HCl means we have 2 of the HCl molecules.
(total of 2 Hydrogen and 2 Chlorine atoms)
• E.g. 6ZnCl2 means we have 6 of the ZnCl2 molecules.
(total of 6 Zinc and 12 Chlorine atoms)
• Tip: Multiply the Coefficient with subscripts to get the
number of atoms.
Balancing Chemical Equations
• Reactants and Products need to have the same number of
atoms for the same elements.
• Elements are not created or destroyed in a chemical reaction.
• Use the Element Inventory to keep track of atoms.
• Change coefficients to match the number of atoms.
E.g.
NaOH + H2SO4 -> Na2SO4 + H2O
Element
Na
S
O
H
Reactants
1
1
5
3
Products
2
1
5
2
Important: Change One Coefficient at a time.
E.g. 2NaOH + H2SO4 -> Na2SO4 + H2O
Element
Na
S
O
H
Reactants
2
1
6
4
Products
2
1
5
2
E.g. 2NaOH + H2SO4 -> Na2SO4 + 2H2O
Element
Na
S
O
H
Reactants
2
1
6
4
Products
2
1
6
4
Done!
Can you balance these chemical equations?
1. NaCl + BeF2 -> NaF + BeCl2
2NaCl + BeF2 -> 2NaF + BeCl2
2. FeCl3 + Be3(PO4)2 -> BeCl2 + FePO4
2FeCl3 + Be3(PO4)2 -> 3BeCl2 + 2FePO4
3. CH4 + O2 -> CO2 + H2O
CH4 + O2 -> CO2 + 2H2O
4. AgNO3 + LiOH -> AgOH + LiNO3
AgNO3 + LiOH -> AgOH + LiNO3
A Beginner’s Guide to Balancing Equations
• https://www.youtube.com/watch?v=_B735turDoM