Law of Conservation of Mass/Balancing Equations

What is a coefficient?

• The small number on the right of the chemical symbol.
• The large number to the left of a formula.

Which side of a chemical equation is the product side?

• Left (before the arrow)
• Right (after the arrow)

Which side of a chemical equation is the reactant side?

• Left (before the arrow)
• Right (after the arrow)

Which problem is balanced?

• PbO₂ + 2H₂
• SO₂ + H₂0 --> H₂SO₄
• 2Na + 2H₂O --> 2NaOH + H₂

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

• Yes
• No

What is the little number after an element in a chemical equation called.
Example: H₂

• Coefficient 
• Subscript
• Atom
• Equation

What is the arrow in a chemical equation...
H_{2 +} O --> H₂O

• Reactants
• Products 
• Produces
• Chemical Equation 

Balance this equation
_Zn+_HCl-->_ZnCl₂ +_H₂

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

Balance this equation.
_Mg + _Cl₂ --> _MgCl₂

• 1, 2,1
• already balanced
• 2,1,1
• 1,1,2

What does the Law of Conservation of Mass state?

• Matter cannot be gained or lost in a chemical reaction.
• Matter can only be lost in a chemical reaction.
• Matter can only be gained in a chemical reaction.
• Matter can be gained and lost in a chemical reaction.