Balancing Equations / Conservation of Mass

What law governs the balancing of chemical equations?

• Law of Energy

• Law of Conservation of Matter/Mass

• Law of Gravity

• Law of Matter Movement

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

• Reactants
• Products 
• Yields 
• Chemical Equation 

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

• Reactants
• Products 
• Yields 
• Chemical Equation 

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. 

In the equation, 2Mg + O₂ ---> 2MgO, which are the reactants?

• Mg and O

• Mg and MgO

• MgO

• O and MgO

Answer explanation

Balance this equation

_Al +_HCl --> _H₂ +_AlCl₃

• 2,6,3,2

• it's already balanced

• 4,12,3,4

• 2,1,4,5

How many HCl molecules do you need to balance this equation? 
Mg +  __HCl --->  MgCl₂ + H₂

• 1
• 2
• 3
• 4

Balance the following equation:

___ SeCl₆+ ___ O₂→___ SeO_{2+____}Cl₂

• 1, 1, 1, 3

• 2, 1, 2, 1

• 1, 2, 1, 2

• 2, 2, 2, 4

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

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

Pb(NO₃)₂  +  KI --> PbI₂ + KNO₃
What type of reaction is this? 

• Synthesis 
• Decomposition 
• Single Replacement
• Double Replacement