Honors Chemistry: Avogadro’s Number and Molar Mass

Flashcards covering key concepts from the Honors Chemistry lecture on Avogadro’s Number, Molar Mass, Percent Composition, and Empirical Formulas.

Avogadro's Number

6.022 x 10^23, the number of particles in one mole of a substance.

Molar Mass

The mass in grams of one mole of a substance.

Empirical Formula

The simplest ratio of the elements in a compound.

Percent Composition

The percent by mass of each element in a compound.

Molecular Formula

The complete formula that shows the actual number of atoms of each element in a molecule.

Conversion from Moles to Atoms

To convert moles into atoms, multiply by Avogadro's number.

Conversion from Atoms to Moles

To convert atoms into moles, divide by Avogadro's number.

Average Atomic Mass

The molar mass of an element as listed on the periodic table.

Percent Composition Calculation

To calculate percent composition, use the formula [(mass of element)/(total mass of compound)] x 100.

Example of Molar Mass Calculation for H2O

The molar mass of H2O is 18.02 grams.

Calculation Steps for Empirical Formula

1. Determine mass percent, 2. Convert percents to grams, 3. Convert grams to moles, 4. Divide all mole amounts by the smallest amount.