Balancing Chemical Equations

The Law of Conservation of Matter

• tells how many atoms of an element are contained in one molecule or formula unit.

• the starting materials in a chemical reaction

• the new substances that are formed in a chemical reaction

• A law stating that atoms are not created or destroyed during a chemical reaction.

Is the equation balanced?: 2H₂O + O₂ --> 4MgO + 3Fe

• yes

• no

Balance this equation

_Al +_HCl --> _H₂ +_AlCl₃

• 2,6,3,2

• it's already balanced

• 4,12,3,4

• 2,1,4,5

Is this equation balanced?

• yes
• no
• Not enough information

What is the left part of a chemical equation called?
2H_{2 +} O₂ --> 2H₂O

• Reactants
• Products 
• Yields 
• Chemical Equation 

What is the number before a chemical formula called?
Ex: 2H₂ + O₂ --> 2H₂O

• Coefficient
• Subscript
• Atom
• Equation

Is the following equation balanced?
4Fe + 3O₂ --> 2Fe₂O₃

• yes
• no

Which of the following equations are correctly balanced?

• 12CO₂ +H₂O --> C₆H₁₂O₆ + O₂
• CO₂ + 9H₂O --> C₆H₁₂O₆ + O₂
• CO₂ + H₂O --> 3C₆H₁₂O₆ + O₂
• 6CO₂ + 6H₂O --> C₆H₁₂O₆ + 6O₂

Balance this equation
_N₂ + _H₂ --> _NH₃

• 1,2,3
• 1,3,2
• 1,1,2
• 2,1,1

Balance this equation.
_CF₄ + _Br₂ -- _CBr₄ + _F₂

• 2,1,2,1
• 1,2,2,1
• 1,2,1,2
• 2,2,2,2