Study Guide: Moles & Mole Road

Molar mass

The mass of one mole of a substance, expressed in grams per mole (g/mol).

Gram atomic mass

The mass of one mole of atoms of an element, expressed in grams per mole.

Gram formula mass

The mass of one mole of a compound's formula, summing the atomic masses of all atoms in the formula.

Gram molecular mass

The mass of one mole of a molecular substance, calculated by summing the atomic masses of its constituent atoms.

1 mole of a substance

If the molar mass is 100.0 grams and you have 100.0 grams, you have 1 mole of the substance.

Avogadro's number

A unit of measurement representing 6.022 x 10²³ particles of a substance.

Gram atomic mass of carbon-12

12.01 g/mol.

Gram atomic mass of carbon-13

Approximately 13.00 g/mol.

Mole of atoms

You would have 6.022 x 10²³ atoms.

Mole of molecules

You would have 6.022 x 10²³ molecules.

Mole of ions

You would have 6.022 x 10²³ ions.

Formula for ammonium hydroxide

NH₄OH.

Classification of NH₄OH

Classified as a molecular formula.

Formula unit

The lowest whole number ratio of ions in an ionic compound.

Molecular formula

Represents the actual number of atoms in a molecule of a covalent compound.

Classification of H₂O

H₂O is a molecular formula.

Salt

A substance composed of a cation from a base and an anion from an acid.

Molar mass of ammonium hydroxide

Approximately 35.05 g/mol.

Calculation for NH₄OH

14.01 (N) + 4.00 (H) + 16.00 (O) + 1.01 (H) = 35.05 g/mol.

Multiplying Avogadro’s number by 3

1.80666 x 10²⁴.

Dividing Avogadro’s number by 3

Approximately 2.00733 x 10²².

Number of molecules in one mole

6.022 x 10²³ molecules.

Moles in 18.02 grams of water

Approximately 1 mole (6.022 x 10²³ molecules) of water.

Moles of oxygen in 18.02 grams of water

1 mole of oxygen atoms (6.022 x 10²³ oxygen atoms).

Moles of hydrogen in 18.02 grams of water

2 moles of hydrogen atoms (2 * 6.022 x 10²³ = 1.2044 x 10²⁴ hydrogen atoms).

Moles in 36.04 grams of water

2 moles of water.

Moles in 72.08 grams of water

4 moles of water.

Atoms in half a mole

Approximately 3.011 x 10²³ atoms.

Atoms in 5 moles

5 * 6.022 x 10²³ = 3.011 x 10²⁴ atoms.

Measurement of a mole

Measured by mass rather than by counting each particle.

Representative particle

Can be an atom, molecule, formula unit, or ion, depending on the substance.

Atoms in half a mole

Approximately 3.011 x 10²³ atoms.

Molecules in one quarter mole

Approximately 1.506 x 10²³ molecules.

Formula units in 10 moles

10 * 6.022 x 10²³ = 6.022 x 10²⁴ formula units.

Ions in 5 moles

5 * 6.022 x 10²³ = 3.011 x 10²⁴ ions.

STP

Standard Temperature and Pressure.

Conditions for STP

0 degrees Celsius (273.15 K) and 1 atmosphere (atm) pressure.

Mass of one mole of oxygen gas (O₂)

32.00 grams.

Atoms in one mole of oxygen gas

Comprises 2 atoms for O₂.

Molecules in one mole of oxygen gas

6.022 x 10²³ molecules.

Volume occupied by one mole of gas at STP

22.4 liters.

Significance of 22.4 liters

Volume occupied by one mole of any gas at STP.

Moles in 32.07 grams of sulfur

Approximately 1 mole.

Diatomic elements

Hydrogen (H₂), nitrogen (N₂), oxygen (O₂), fluorine (F₂), chlorine (Cl₂), bromine (Br₂), and iodine (I₂).

Molar mass of chlorine gas (Cl₂)

Approximately 70.90 g/mol.

Molar mass of nitrogen gas (N₂)

Approximately 28.02 g/mol.