The Mole and Molar Mass
One mole contains 6.022 x 1023 entities, and molar mass is the mass in grams of one mole of a substance.
What is The Mole and Molar Mass?
One mole contains 6.022 x 1023 entities, and molar mass is the mass in grams of one mole of a substance.
Key formula / rule: Moles equal mass divided by molar mass.
Key points
- Define the mole and compute molar mass from a chemical formula.
- Compute the number of particles, mass or volume from a given amount in moles.
Common exam trap
Using molecular mass in grams where formula-unit mass is required for ionic solids.
Definitions
- Term
The Mole and Molar Mass
- Meaning
One mole contains 6.022 x 1023 entities, and molar mass is the mass in grams of one mole of a substance.
- Term
The Mole and Molar Mass — explanation
- Meaning
The mole converts between the laboratory scale of grams and the particle scale of atoms and molecules. Every stoichiometric calculation is a chain of unit conversions anchored on this single bridge.
Learning objectives
Define the mole and compute molar mass from a chemical formula.
Compute the number of particles, mass or volume from a given amount in moles.
Formulae
- Key point
Moles equal mass divided by molar mass.
- Key point
One mole of any ideal gas occupies 22.4 L at STP.
- Key point
Avogadro's number links moles to the number of particles.
Common mistakes
Using molecular mass in grams where formula-unit mass is required for ionic solids.
Applying 22.4 L per mole to a gas that is not at STP.
Keywords
Mole
Molar
Mass
Practice preview
Which of the following statements regarding moles and molar mass is INCORRECT?…
hard
What is the molar mass of water (H2O)? (Atomic masses: H = 1 g/mol, O = 16 g/mol)…
easy
How many molecules are present in 0.5 moles of oxygen gas (O2)?…
easy