Stoichiometry
Table of Contents
1. Definition
Stoichiometry is the measure of elements and the relationships between reactants used and products and is based on the Law of Conservation of Mass. Hence, to utilize Stoichiometry to its fullest potential it is imperative that the equation is balanced.
1.1. Ensure Compliance with the Law of Conservation of Mass
To ensure the afformentioned law, the mass of each reactant must be equal to its product.
1.2. Usage of Molar Mass to Calculate the Mass of Compounds
The molar mass of reactants used to manufacture a compound can be summed to an estimated molar mass of the compound.
1.3. Mol(A) -> Mol(B)
- Find the mole ratio of the formula
- Multiply the given amount of molecule with the mole ratio.
1.3.1. Example
- How many moles of Lithium Hydroxide (\(LiOH\)) are required to produce 20 moles of Carbon Dioxide (\(CO_{2}\))
[\(1CO_{2} + 2LiOH -> 1Li_{2}CO_{3} + 1H_{2}O\)]
- Ratio of \(LiOH\) to \(CO_{2}\)
- \(2:1\)
- Use formula to multiply given molucule with ratio
- \(20 \times \frac{2}{1}=40\)
- Ratio of \(LiOH\) to \(CO_{2}\)
1.4. Mol(A) -> Mass(B)
- Find the mole ratio of the formula
- Multiply the given amount of molecule with the mole ratio.
- Multiply the result by the molar mass of oxygen
1.5. Mass(A) -> Mol(B)
- Divide the given mass by the molar mass of the given.
- Multiply the result by the mole ratio
1.6. Mass(A) -> Mass(B)
- Divide the given mass by its molar mass
- Multiply the result by the ratio
- Multiply the result by the molar mass of the expected compound/element
1.7. Percent Yield
A percent yield is determined by the limiting reactant in your calculations. The actual yield is given via problem, it can be reffered to as "experimental yield". \(Yield=100\frac{actual}{theoratical}\)
2. Cheat Sheet
2.1. Mole / Mass Conversions
For \(G\) as the given, and \(GM\) as the given mass, and \(MR\) as the mole ratio and \(MM\) as the molar mass.
- Mol(A) -> Mol(B)
- \(G \times MR\)
- Mol(A) -> Mass(B)
- \(G_{A} \times MR \times MM_{B}\)
- Mass(A) -> Mol(B)
- \(\frac{G_{A}}{MM_{A}} \times MR\)
- Mass(A) -> Mass(B)
- \(\frac{GM_{A}}{MM_{A}} \times MR \times MM_{B}\)