Stoichiometry

Stoichiometry Glossary

• Mole: Amount equal to the number of atoms in 12 grams of carbon-12.

• Molar Mass: Mass in grams of one mole of a substance.

• Stoichiometry: Study of relationships between reactants and products in a chemical reaction.

The Mole

• Avogadro’s Number: $6.022 imes 10^{23}$ particles/mole.

• One mole of any substance contains $6.022 imes 10^{23}$ particles.

• Mass of one mole of an element (grams) equals its atomic weight.

Mole Conversions

• Moles to Particles: Multiply moles by $6.022 imes 10^{23}$.

• Particles to Moles: Divide number of particles by $6.022 imes 10^{23}$.

Finding Number of Atoms

• To find atoms in a substance: Multiply moles by Avogadro's number.

• Example: For 1.70 moles of MgBr2, calculate atoms of bromine.

Molar Mass Calculations

• Molar Mass of Compound: Sum of molar masses of its constituent elements.

• Example for NH3:

  • Nitrogen: 1 × 14.007 g/mol.

  • Hydrogen: 3 × 1.008 g/mol = 3.024 g/mol.

  • Total molar mass = Nitrogen + Hydrogen.

Conversions Between Moles and Grams

• Grams to Moles: Divide grams by molar mass.

• Moles to Grams: Multiply moles by molar mass.

• Use periodic table for molar masses.

Stoichiometric Ratios

• Use balanced chemical equations to find amounts of reactants/products.

• Law of Conservation of Matter: Total mass before and after reaction remains constant.

Example Reactions

• SiO2 + 4HF → SiF4 + 2H2O: Understand conversion between grams and moles using stoichiometry.

Application of Stoichiometry

• Solve real-world problems by calculating moles, grams, and particles based on reactions.

• Example: How many molecules of dinitrogen trioxide (N2O3) are needed to produce nitrogen gas (N2)?