Chemical Equations and Balancing

Balancing Chemical Equations

Monday Nov 16

Open Ended

What do you think is the purpose of using coefficients in chemical equations?

Multiple Choice

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.

Multiple Choice

How many atoms of carbon (C) are in C₆H₁₂O₆?

• 3
• 6
• 12
• 24

Multiple Choice

How many Sodium (Na) are in 6NaCl?

• 1
• 12
• 6

Multiple Choice

How many Hydrogen (H) atoms are in 4H₂O?

• 6

• 8

• 2

• 4

How to balance chemical equations:

• Determine the number of atoms for each element on both sides of the arrow (use subscripts)

• Choose one element to balance (both sides should have the same number of atoms)

• Use coefficients to balance the atoms

• You can NOT change the subscripts

• Tip: Balance Oxygen and Hydrogen last!

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

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

• yes

• no

Now it's your turn!

Practice balancing different chemical equations. There are 40 practice problems located in your notes! Practice practice practice!