Lecture: Balancing Chemical Equations

Balancing Chemical Equations

Multiple Choice

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. 

REMEMBER

# of each element in reactants

MUST EQUAL

# of each element in products

​Why we ned to balanced a chemical equation?

​to obey the Law of Conservation fo Matter

Multiple Choice

What are the larger numbers that you CAN CHANGE in a chemical equation? 

• Coefficient 
• Products
• Reactants
• Subscripts

Multiple Choice

Balance this equation

_Al +_HCl --> _H₂ +_AlCl₃

• 2,6,3,2

• it's already balanced

• 4,12,3,4

• 2,1,4,5

Multiple Choice

What is the right ratio of chemicals for the BCE (Balanced Chemical Equation)?__FeCl₃ + __Ca(OH)₂ --> __Fe(OH)₃ + __CaCl₂

• 4,3--> 2,1
• 3,2 --> 3,1
• 2,3 --> 2,2
• 2,3 --> 2,3

Multiple Choice

__BF₃ + __Li₂SO₃ --> __B₂(SO₃)₃ + __LiF

• 2,3,1,3
• 2,3,1,6
• 4,4,2,12
• 3,3,1,9

Open Ended

ammonium dichromate  decomposes to make chromium (III) oxide,  nitrogen gas, and  water

write the balance chemical equation and identify the type of reaction

Open Ended

iron (III) chloride  reacts with  ammonium hydroxide  to make  iron (III) hydroxide  and  ammonium chloride

Write the balance chemical equations and determine the type of reaction