Molar Ratio
Related Examples and Practice Problems
Additional Worked Out Examples/ Practice
Identifying classification types: Differentiation between elements, compounds or mixtures and homogeneous and heterogenous mixtures
Separation techniques: Selected and explaining limitation of appropriate separation
Relating Properties to Composition: Predicting classification based on descriptive properties
Topic Summary & Highlights
and Help Videos
Core Concept
Mole ratio is the ratio of the moles of one substance to the moles of another substance in a balanced chemical equation. Mole ratios are essential in stoichiometry as they allow us to calculate the amounts of reactants and products involved in a chemical reaction.
Practice Tips
Memorize Common Ions: Focus on learning the common polyatomic ions, charges, and patterns.
Roman Numerals for Transition Metals: Practice associating transition metals with their possible charges.
Cross-Method for Formulas: To determine the correct formula, use the “criss-cross” method to balance charges between cations and anions.
Key Concepts
Understanding Mole Ratio:
The mole ratio is determined from the coefficients in a balanced chemical equation.
These coefficients represent the number of moles of each reactant and product.
For example, in the reaction 2H₂ + O₂ → 2H₂O, the mole ratio of H₂ to O₂ is 2:1, and the mole ratio of H₂ to H₂O is 2:2, which simplifies to 1:1.
Example Problem: Using Mole Ratios in a Reaction
Problem: In the reaction below, how many moles of H2O\text{H}_2\text{O}H2O are produced if 4.0 moles of O2\text{O}_2O2 react completely?
$2\text{H}_2 + \text{O}_2 \rightarrow 2\text{H}_2\text{O}$
Solution:
Write and Balance the Equation:
The equation is already balanced.
Identify the Mole Ratio:
The mole ratio of O₂ to H₂O is 1:2, as indicated by the coefficients.
Set Up the Conversion:
To find the moles of H₂O from 4.0 moles of O₂, use the mole ratio:
$4.0 \, \text{moles O}_2 \times \frac{2 \, \text{moles H}_2\text{O}}{1 \, \text{mole O}_2} = 8.0 \, \text{moles H}_2\text{O}$
Answer: 8.0 moles of H₂O are produced.
