Unit 8: Stoichiometry Lecture Notes

Vocabulary and key concepts from Unit 8 Stoichiometry, covering balanced equations, mass/mole conversions, limiting reactants, and percent yield.

Stoichiometry

Derived from the Greek words for "element" and "to measure".

Balanced Equation

An equation that must be established first for arithmetic of equations, such as $1 N_2 + 3 H_2 \rightarrow 2 NH_3$.

Conserved Entities

Properties in a chemical equation that always have the same number on both sides, specifically grams and atoms.

Non-conserved Entities

Properties in a chemical equation that do not have to be conserved on both sides, specifically volume, moles, and molecules.

Mole to Mole Calculation

A one-step problem that uses coefficients from a balanced equation as a conversion factor.

Mass to Mass Calculation

A 3-step problem involving the sequence: $\text{g given} \rightarrow \text{mol given} \rightarrow \text{mol want} \rightarrow \text{g want}$.

Molar Mass (mm)

The calculation factor used when converting between grams and moles ($g \rightarrow mol$ or $mol \rightarrow g$).

Molar Volume constant

For gases, the volume used where $1 \text{ mol}$ of nitrogen reacts as $22.4 L$.

Avogadro's Number

The conversion factor for particles used in calculations, equal to $6.02 \times 10^{23}$ molecules/mol.

Limiting Reactant (Reagent)

The reactant that is run out of first in a reaction, which limits how much product will be made.

Excess Reactant

The reactant that remains extra after the reaction has ceased.

Theoretical Yield

The amount of product that can be calculated on paper.

Actual Yield

The amount of product that is actually made, which is usually given in a lab scenario or found experimentally.

Percent Yield

The calculation of efficiency expressed as: \text{\text{% Yield}} = \frac{\text{actual}}{\text{theoretical}} \times 100.