The Basics
This law states that matter is neither created nor destroyed in a chemical reaction.
What is the Law of Conservation of Mass?
The number of hydrogen atoms present in one molecule of H₂O.
What is 2?
The balanced form of this equation:
H₂ + O₂ → H₂O
What is 2H₂ + O₂ → 2H₂O?
The balanced form of this equation:
Ca + H₂O → Ca(OH)₂ + H₂
What is Ca + 2H₂O → Ca(OH)₂ + H₂?
Double Points: Coefficients in a balanced equation should always be written in this form.
What is the lowest whole-number ratio?
These numbers in front of chemical formulas show how many molecules are involved.
What are coefficients?
Double Points: The total number of hydrogen atoms in 4NH₃.
What is 12?
The balanced form of this equation:
N₂ + H₂ → NH₃
What is N₂ + 3H₂ → 2NH₃?
The balanced form of this equation:
Fe + O₂ → Fe₂O₃
What is 4Fe + 3O₂ → 2Fe₂O₃?
This part of a chemical formula should never be changed when balancing equations.
What are subscripts?
This must be equal on both sides of a balanced chemical equation.
What is the number of each type of atom?
The total number of oxygen atoms in 3O₂.
What is 6?
The balanced form of this equation:
Na + Cl₂ → NaCl
What is 2Na + Cl₂ → 2NaCl?
Double Points: The balanced form of this equation:
Na + H₂O → NaOH + H₂
What is 2Na + 2H₂O → 2NaOH + H₂?
These elements are usually balanced last in chemical equations.
What are hydrogen and oxygen?
This side of the equation lists the starting substances.
What are the reactants?
The number of carbon atoms in 2CO₂.
What is 2?
Double Points: The balanced form of this equation:
Al + O₂ → Al₂O₃
What is 4Al + 3O₂ → 2Al₂O₃?
The balanced form of this equation:
Zn + HCl → ZnCl₂ + H₂
What is Zn + 2HCl → ZnCl₂ + H₂?
This is done after all atoms appear balanced to ensure the equation is correct.
What is checking the equation?
Double Points: This side of the equation lists the substances that are formed.
What are the products?
The total number of atoms in one formula unit of NaCl.
What is 2
The balanced form of this equation:
Mg + O₂ → MgO
What is 2Mg + O₂ → 2MgO?
The balanced form of this equation:
K + H₂O → KOH + H₂
What is 2K + 2H₂O → 2KOH + H₂?
This is the first step you should take when balancing a chemical equation.
What is counting the atoms on both sides?